diff --git a/backend/src/features/ownership-costs/README.md b/backend/src/features/ownership-costs/README.md
new file mode 100644
index 0000000..f5a184c
--- /dev/null
+++ b/backend/src/features/ownership-costs/README.md
@@ -0,0 +1,153 @@
+# Ownership Costs Feature
+
+Tracks vehicle ownership costs including insurance, registration, tax, inspection, parking, and other costs.
+
+## Database Schema
+
+```sql
+ownership_costs (
+  id UUID PRIMARY KEY,
+  user_id VARCHAR(255) NOT NULL,
+  vehicle_id UUID NOT NULL REFERENCES vehicles(id) ON DELETE CASCADE,
+  document_id UUID NULL REFERENCES documents(id) ON DELETE CASCADE,
+  cost_type VARCHAR(32) NOT NULL CHECK (cost_type IN ('insurance', 'registration', 'tax', 'inspection', 'parking', 'other')),
+  amount DECIMAL(10, 2) NOT NULL CHECK (amount > 0),
+  description VARCHAR(200),
+  period_start DATE,
+  period_end DATE,
+  notes TEXT,
+  created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
+  updated_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP
+)
+```
+
+## API Endpoints
+
+### POST /ownership-costs
+Create a new ownership cost record.
+
+**Auth**: Required (JWT)
+
+**Request Body**:
+```json
+{
+  "vehicleId": "uuid",
+  "documentId": "uuid (optional)",
+  "costType": "insurance | registration | tax | inspection | parking | other",
+  "amount": 150.00,
+  "description": "Auto insurance premium (optional)",
+  "periodStart": "2024-01-01 (optional)",
+  "periodEnd": "2024-12-31 (optional)",
+  "notes": "Additional notes (optional)"
+}
+```
+
+**Response**: 201 Created
+```json
+{
+  "id": "uuid",
+  "userId": "string",
+  "vehicleId": "uuid",
+  "documentId": "uuid",
+  "costType": "insurance",
+  "amount": 150.00,
+  "description": "Auto insurance premium",
+  "periodStart": "2024-01-01",
+  "periodEnd": "2024-12-31",
+  "notes": "Additional notes",
+  "createdAt": "2024-01-01T00:00:00.000Z",
+  "updatedAt": "2024-01-01T00:00:00.000Z"
+}
+```
+
+### GET /ownership-costs
+List all ownership costs for the authenticated user.
+
+**Auth**: Required (JWT)
+
+**Query Parameters**:
+- `vehicleId` (optional): Filter by vehicle UUID
+- `costType` (optional): Filter by cost type
+- `documentId` (optional): Filter by document UUID
+
+**Response**: 200 OK
+```json
+[
+  {
+    "id": "uuid",
+    "userId": "string",
+    "vehicleId": "uuid",
+    "costType": "insurance",
+    "amount": 150.00,
+    "description": "Auto insurance premium",
+    "periodStart": "2024-01-01",
+    "periodEnd": "2024-12-31",
+    "createdAt": "2024-01-01T00:00:00.000Z",
+    "updatedAt": "2024-01-01T00:00:00.000Z"
+  }
+]
+```
+
+### GET /ownership-costs/:id
+Get a specific ownership cost record.
+
+**Auth**: Required (JWT)
+
+**Response**: 200 OK (same as POST response)
+
+**Errors**:
+- 404 Not Found: Cost not found or not owned by user
+
+### PUT /ownership-costs/:id
+Update an ownership cost record.
+
+**Auth**: Required (JWT)
+
+**Request Body**: (all fields optional)
+```json
+{
+  "documentId": "uuid",
+  "costType": "insurance",
+  "amount": 160.00,
+  "description": "Updated description",
+  "periodStart": "2024-01-01",
+  "periodEnd": "2024-12-31",
+  "notes": "Updated notes"
+}
+```
+
+**Response**: 200 OK (same as POST response)
+
+**Errors**:
+- 404 Not Found: Cost not found or not owned by user
+
+### DELETE /ownership-costs/:id
+Delete an ownership cost record.
+
+**Auth**: Required (JWT)
+
+**Response**: 204 No Content
+
+**Errors**:
+- 404 Not Found: Cost not found or not owned by user
+
+## Cost Types
+
+| Type | Description |
+|------|-------------|
+| insurance | Auto insurance premiums |
+| registration | Vehicle registration fees |
+| tax | Property or excise taxes |
+| inspection | State inspection fees |
+| parking | Parking permits, monthly fees |
+| other | Other ownership costs |
+
+## Authorization
+
+All endpoints enforce user scoping - users can only access their own ownership cost records. Vehicle ownership is verified before creating records.
+
+## Integration with Other Features
+
+- **Documents**: Optional document_id links costs to supporting documents
+- **Vehicles**: vehicle_id foreign key with CASCADE delete
+- **TCO Calculation**: Service provides `getVehicleOwnershipCosts()` for total cost of ownership aggregation
diff --git a/backend/src/features/ownership-costs/api/ownership-costs.controller.ts b/backend/src/features/ownership-costs/api/ownership-costs.controller.ts
index ca3326f..05f57f9 100644
--- a/backend/src/features/ownership-costs/api/ownership-costs.controller.ts
+++ b/backend/src/features/ownership-costs/api/ownership-costs.controller.ts
@@ -1,225 +1,145 @@
-/**
- * @ai-summary Fastify route handlers for ownership costs API
- * @ai-context HTTP request/response handling with Fastify reply methods
- */
-
-import { FastifyRequest, FastifyReply } from 'fastify';
+import { FastifyReply, FastifyRequest } from 'fastify';
 import { OwnershipCostsService } from '../domain/ownership-costs.service';
-import { pool } from '../../../core/config/database';
+import type { CreateBody, UpdateBody, IdParams, ListQuery } from './ownership-costs.validation';
 import { logger } from '../../../core/logging/logger';
-import {
-  OwnershipCostParams,
-  VehicleParams,
-  CreateOwnershipCostBody,
-  UpdateOwnershipCostBody
-} from '../domain/ownership-costs.types';
 
 export class OwnershipCostsController {
-  private service: OwnershipCostsService;
+  private readonly service = new OwnershipCostsService();
 
-  constructor() {
-    this.service = new OwnershipCostsService(pool);
+  async list(request: FastifyRequest<{ Querystring: ListQuery }>, reply: FastifyReply) {
+    const userId = (request as any).user?.sub as string;
+
+    logger.info('Ownership costs list requested', {
+      operation: 'ownership-costs.list',
+      userId,
+      filters: {
+        vehicleId: request.query.vehicleId,
+        costType: request.query.costType,
+        documentId: request.query.documentId,
+      },
+    });
+
+    const costs = await this.service.getCosts(userId, {
+      vehicleId: request.query.vehicleId,
+      costType: request.query.costType,
+      documentId: request.query.documentId,
+    });
+
+    logger.info('Ownership costs list retrieved', {
+      operation: 'ownership-costs.list.success',
+      userId,
+      costCount: costs.length,
+    });
+
+    return reply.code(200).send(costs);
   }
 
-  async create(request: FastifyRequest<{ Body: CreateOwnershipCostBody }>, reply: FastifyReply) {
-    try {
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      const userId = (request as any).user.sub;
-      const cost = await this.service.create(request.body, userId);
+  async get(request: FastifyRequest<{ Params: IdParams }>, reply: FastifyReply) {
+    const userId = (request as any).user?.sub as string;
+    const costId = request.params.id;
 
-      return reply.code(201).send(cost);
-    } catch (error: unknown) {
-      const err = error as Error;
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      logger.error('Error creating ownership cost', { error: err, userId: (request as any).user?.sub });
+    logger.info('Ownership cost get requested', {
+      operation: 'ownership-costs.get',
+      userId,
+      costId,
+    });
 
-      if (err.message.includes('not found')) {
-        return reply.code(404).send({
-          error: 'Not Found',
-          message: err.message
-        });
-      }
-      if (err.message.includes('Unauthorized')) {
-        return reply.code(403).send({
-          error: 'Forbidden',
-          message: err.message
-        });
-      }
-
-      return reply.code(500).send({
-        error: 'Internal server error',
-        message: 'Failed to create ownership cost'
+    const cost = await this.service.getCost(userId, costId);
+    if (!cost) {
+      logger.warn('Ownership cost not found', {
+        operation: 'ownership-costs.get.not_found',
+        userId,
+        costId,
       });
+      return reply.code(404).send({ error: 'Not Found' });
     }
+
+    logger.info('Ownership cost retrieved', {
+      operation: 'ownership-costs.get.success',
+      userId,
+      costId,
+      vehicleId: cost.vehicleId,
+      costType: cost.costType,
+    });
+
+    return reply.code(200).send(cost);
   }
 
-  async getByVehicle(request: FastifyRequest<{ Params: VehicleParams }>, reply: FastifyReply) {
-    try {
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      const userId = (request as any).user.sub;
-      const { vehicleId } = request.params;
+  async create(request: FastifyRequest<{ Body: CreateBody }>, reply: FastifyReply) {
+    const userId = (request as any).user?.sub as string;
 
-      const costs = await this.service.getByVehicleId(vehicleId, userId);
+    logger.info('Ownership cost create requested', {
+      operation: 'ownership-costs.create',
+      userId,
+      vehicleId: request.body.vehicleId,
+      costType: request.body.costType,
+      amount: request.body.amount,
+    });
 
-      return reply.code(200).send(costs);
-    } catch (error: unknown) {
-      const err = error as Error;
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      logger.error('Error listing ownership costs', { error: err, vehicleId: request.params.vehicleId, userId: (request as any).user?.sub });
+    const created = await this.service.createCost(userId, request.body);
 
-      if (err.message.includes('not found')) {
-        return reply.code(404).send({
-          error: 'Not Found',
-          message: err.message
-        });
-      }
-      if (err.message.includes('Unauthorized')) {
-        return reply.code(403).send({
-          error: 'Forbidden',
-          message: err.message
-        });
-      }
+    logger.info('Ownership cost created', {
+      operation: 'ownership-costs.create.success',
+      userId,
+      costId: created.id,
+      vehicleId: created.vehicleId,
+      costType: created.costType,
+      amount: created.amount,
+    });
 
-      return reply.code(500).send({
-        error: 'Internal server error',
-        message: 'Failed to get ownership costs'
-      });
-    }
+    return reply.code(201).send(created);
   }
 
-  async getById(request: FastifyRequest<{ Params: OwnershipCostParams }>, reply: FastifyReply) {
-    try {
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      const userId = (request as any).user.sub;
-      const { id } = request.params;
+  async update(request: FastifyRequest<{ Params: IdParams; Body: UpdateBody }>, reply: FastifyReply) {
+    const userId = (request as any).user?.sub as string;
+    const costId = request.params.id;
 
-      const cost = await this.service.getById(id, userId);
+    logger.info('Ownership cost update requested', {
+      operation: 'ownership-costs.update',
+      userId,
+      costId,
+      updateFields: Object.keys(request.body),
+    });
 
-      return reply.code(200).send(cost);
-    } catch (error: unknown) {
-      const err = error as Error;
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      logger.error('Error getting ownership cost', { error: err, costId: request.params.id, userId: (request as any).user?.sub });
-
-      if (err.message.includes('not found')) {
-        return reply.code(404).send({
-          error: 'Not Found',
-          message: err.message
-        });
-      }
-      if (err.message.includes('Unauthorized')) {
-        return reply.code(403).send({
-          error: 'Forbidden',
-          message: err.message
-        });
-      }
-
-      return reply.code(500).send({
-        error: 'Internal server error',
-        message: 'Failed to get ownership cost'
+    const updated = await this.service.updateCost(userId, costId, request.body);
+    if (!updated) {
+      logger.warn('Ownership cost not found for update', {
+        operation: 'ownership-costs.update.not_found',
+        userId,
+        costId,
       });
+      return reply.code(404).send({ error: 'Not Found' });
     }
+
+    logger.info('Ownership cost updated', {
+      operation: 'ownership-costs.update.success',
+      userId,
+      costId,
+      vehicleId: updated.vehicleId,
+      costType: updated.costType,
+    });
+
+    return reply.code(200).send(updated);
   }
 
-  async update(request: FastifyRequest<{ Params: OwnershipCostParams; Body: UpdateOwnershipCostBody }>, reply: FastifyReply) {
-    try {
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      const userId = (request as any).user.sub;
-      const { id } = request.params;
+  async remove(request: FastifyRequest<{ Params: IdParams }>, reply: FastifyReply) {
+    const userId = (request as any).user?.sub as string;
+    const costId = request.params.id;
 
-      const updatedCost = await this.service.update(id, request.body, userId);
+    logger.info('Ownership cost delete requested', {
+      operation: 'ownership-costs.delete',
+      userId,
+      costId,
+    });
 
-      return reply.code(200).send(updatedCost);
-    } catch (error: unknown) {
-      const err = error as Error;
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      logger.error('Error updating ownership cost', { error: err, costId: request.params.id, userId: (request as any).user?.sub });
+    await this.service.deleteCost(userId, costId);
 
-      if (err.message.includes('not found')) {
-        return reply.code(404).send({
-          error: 'Not Found',
-          message: err.message
-        });
-      }
-      if (err.message.includes('Unauthorized')) {
-        return reply.code(403).send({
-          error: 'Forbidden',
-          message: err.message
-        });
-      }
+    logger.info('Ownership cost deleted', {
+      operation: 'ownership-costs.delete.success',
+      userId,
+      costId,
+    });
 
-      return reply.code(500).send({
-        error: 'Internal server error',
-        message: 'Failed to update ownership cost'
-      });
-    }
-  }
-
-  async delete(request: FastifyRequest<{ Params: OwnershipCostParams }>, reply: FastifyReply) {
-    try {
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      const userId = (request as any).user.sub;
-      const { id } = request.params;
-
-      await this.service.delete(id, userId);
-
-      return reply.code(204).send();
-    } catch (error: unknown) {
-      const err = error as Error;
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      logger.error('Error deleting ownership cost', { error: err, costId: request.params.id, userId: (request as any).user?.sub });
-
-      if (err.message.includes('not found')) {
-        return reply.code(404).send({
-          error: 'Not Found',
-          message: err.message
-        });
-      }
-      if (err.message.includes('Unauthorized')) {
-        return reply.code(403).send({
-          error: 'Forbidden',
-          message: err.message
-        });
-      }
-
-      return reply.code(500).send({
-        error: 'Internal server error',
-        message: 'Failed to delete ownership cost'
-      });
-    }
-  }
-
-  async getVehicleStats(request: FastifyRequest<{ Params: VehicleParams }>, reply: FastifyReply) {
-    try {
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      const userId = (request as any).user.sub;
-      const { vehicleId } = request.params;
-
-      const stats = await this.service.getVehicleCostStats(vehicleId, userId);
-
-      return reply.code(200).send(stats);
-    } catch (error: unknown) {
-      const err = error as Error;
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      logger.error('Error getting ownership cost stats', { error: err, vehicleId: request.params.vehicleId, userId: (request as any).user?.sub });
-
-      if (err.message.includes('not found')) {
-        return reply.code(404).send({
-          error: 'Not Found',
-          message: err.message
-        });
-      }
-      if (err.message.includes('Unauthorized')) {
-        return reply.code(403).send({
-          error: 'Forbidden',
-          message: err.message
-        });
-      }
-
-      return reply.code(500).send({
-        error: 'Internal server error',
-        message: 'Failed to get ownership cost stats'
-      });
-    }
+    return reply.code(204).send();
   }
 }
diff --git a/backend/src/features/ownership-costs/api/ownership-costs.routes.ts b/backend/src/features/ownership-costs/api/ownership-costs.routes.ts
index 4a357c7..3742bc5 100644
--- a/backend/src/features/ownership-costs/api/ownership-costs.routes.ts
+++ b/backend/src/features/ownership-costs/api/ownership-costs.routes.ts
@@ -1,56 +1,38 @@
 /**
  * @ai-summary Fastify routes for ownership costs API
- * @ai-context Route definitions with Fastify plugin pattern and authentication
  */
-
-import { FastifyInstance, FastifyPluginOptions } from 'fastify';
-import { FastifyPluginAsync } from 'fastify';
+import { FastifyInstance, FastifyPluginAsync, FastifyPluginOptions } from 'fastify';
 import { OwnershipCostsController } from './ownership-costs.controller';
 
 export const ownershipCostsRoutes: FastifyPluginAsync = async (
   fastify: FastifyInstance,
   _opts: FastifyPluginOptions
 ) => {
-  const controller = new OwnershipCostsController();
+  const ctrl = new OwnershipCostsController();
+  const requireAuth = fastify.authenticate.bind(fastify);
 
-  // POST /api/ownership-costs - Create new ownership cost
-  fastify.post('/ownership-costs', {
-    preHandler: [fastify.authenticate],
-    handler: controller.create.bind(controller)
+  fastify.get('/ownership-costs', {
+    preHandler: [requireAuth],
+    handler: ctrl.list.bind(ctrl)
   });
 
-  // GET /api/ownership-costs/:id - Get specific ownership cost
-  fastify.get('/ownership-costs/:id', {
-    preHandler: [fastify.authenticate],
-    handler: controller.getById.bind(controller)
+  fastify.get<{ Params: any }>('/ownership-costs/:id', {
+    preHandler: [requireAuth],
+    handler: ctrl.get.bind(ctrl)
   });
 
-  // PUT /api/ownership-costs/:id - Update ownership cost
-  fastify.put('/ownership-costs/:id', {
-    preHandler: [fastify.authenticate],
-    handler: controller.update.bind(controller)
+  fastify.post<{ Body: any }>('/ownership-costs', {
+    preHandler: [requireAuth],
+    handler: ctrl.create.bind(ctrl)
   });
 
-  // DELETE /api/ownership-costs/:id - Delete ownership cost
-  fastify.delete('/ownership-costs/:id', {
-    preHandler: [fastify.authenticate],
-    handler: controller.delete.bind(controller)
+  fastify.put<{ Params: any; Body: any }>('/ownership-costs/:id', {
+    preHandler: [requireAuth],
+    handler: ctrl.update.bind(ctrl)
   });
 
-  // GET /api/ownership-costs/vehicle/:vehicleId - Get costs for a vehicle
-  fastify.get('/ownership-costs/vehicle/:vehicleId', {
-    preHandler: [fastify.authenticate],
-    handler: controller.getByVehicle.bind(controller)
-  });
-
-  // GET /api/ownership-costs/vehicle/:vehicleId/stats - Get aggregated cost stats
-  fastify.get('/ownership-costs/vehicle/:vehicleId/stats', {
-    preHandler: [fastify.authenticate],
-    handler: controller.getVehicleStats.bind(controller)
+  fastify.delete<{ Params: any }>('/ownership-costs/:id', {
+    preHandler: [requireAuth],
+    handler: ctrl.remove.bind(ctrl)
   });
 };
-
-// For backward compatibility during migration
-export function registerOwnershipCostsRoutes() {
-  throw new Error('registerOwnershipCostsRoutes is deprecated - use ownershipCostsRoutes Fastify plugin instead');
-}
diff --git a/backend/src/features/ownership-costs/api/ownership-costs.validation.ts b/backend/src/features/ownership-costs/api/ownership-costs.validation.ts
new file mode 100644
index 0000000..654bd08
--- /dev/null
+++ b/backend/src/features/ownership-costs/api/ownership-costs.validation.ts
@@ -0,0 +1,18 @@
+import { z } from 'zod';
+import { CreateOwnershipCostSchema, UpdateOwnershipCostSchema, OwnershipCostTypeSchema } from '../domain/ownership-costs.types';
+
+export const ListQuerySchema = z.object({
+  vehicleId: z.string().uuid().optional(),
+  costType: OwnershipCostTypeSchema.optional(),
+  documentId: z.string().uuid().optional(),
+});
+
+export const IdParamsSchema = z.object({ id: z.string().uuid() });
+
+export const CreateBodySchema = CreateOwnershipCostSchema;
+export const UpdateBodySchema = UpdateOwnershipCostSchema;
+
+export type ListQuery = z.infer<typeof ListQuerySchema>;
+export type IdParams = z.infer<typeof IdParamsSchema>;
+export type CreateBody = z.infer<typeof CreateBodySchema>;
+export type UpdateBody = z.infer<typeof UpdateBodySchema>;
diff --git a/backend/src/features/ownership-costs/data/ownership-costs.repository.ts b/backend/src/features/ownership-costs/data/ownership-costs.repository.ts
index 71aaa7d..6096d06 100644
--- a/backend/src/features/ownership-costs/data/ownership-costs.repository.ts
+++ b/backend/src/features/ownership-costs/data/ownership-costs.repository.ts
@@ -1,210 +1,160 @@
-/**
- * @ai-summary Data access layer for ownership costs
- * @ai-context Handles database operations for vehicle ownership costs
- */
-
 import { Pool } from 'pg';
-import {
-  OwnershipCost,
-  CreateOwnershipCostRequest,
-  UpdateOwnershipCostRequest,
-  CostInterval,
-  OwnershipCostType
-} from '../domain/ownership-costs.types';
+import pool from '../../../core/config/database';
+import type { OwnershipCost, OwnershipCostType } from '../domain/ownership-costs.types';
 
 export class OwnershipCostsRepository {
-  constructor(private pool: Pool) {}
+  constructor(private readonly db: Pool = pool) {}
 
-  async create(data: CreateOwnershipCostRequest & { userId: string }): Promise<OwnershipCost> {
-    const query = `
-      INSERT INTO ownership_costs (
-        user_id, vehicle_id, document_id, cost_type, description,
-        amount, interval, start_date, end_date
-      )
-      VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)
-      RETURNING *
-    `;
+  // ========================
+  // Row Mappers
+  // ========================
 
-    const values = [
-      data.userId,
-      data.vehicleId,
-      data.documentId ?? null,
-      data.costType,
-      data.description ?? null,
-      data.amount,
-      data.interval,
-      data.startDate,
-      data.endDate ?? null
-    ];
-
-    const result = await this.pool.query(query, values);
-    return this.mapRow(result.rows[0]);
+  private mapRow(row: any): OwnershipCost {
+    return {
+      id: row.id,
+      userId: row.user_id,
+      vehicleId: row.vehicle_id,
+      documentId: row.document_id,
+      costType: row.cost_type,
+      amount: row.amount,
+      description: row.description,
+      periodStart: row.period_start,
+      periodEnd: row.period_end,
+      notes: row.notes,
+      createdAt: row.created_at,
+      updatedAt: row.updated_at
+    };
   }
 
-  async findByVehicleId(vehicleId: string, userId: string): Promise<OwnershipCost[]> {
-    const query = `
-      SELECT * FROM ownership_costs
-      WHERE vehicle_id = $1 AND user_id = $2
-      ORDER BY start_date DESC, created_at DESC
-    `;
+  // ========================
+  // CRUD Operations
+  // ========================
 
-    const result = await this.pool.query(query, [vehicleId, userId]);
-    return result.rows.map(row => this.mapRow(row));
-  }
-
-  async findByUserId(userId: string): Promise<OwnershipCost[]> {
-    const query = `
-      SELECT * FROM ownership_costs
-      WHERE user_id = $1
-      ORDER BY start_date DESC, created_at DESC
-    `;
-
-    const result = await this.pool.query(query, [userId]);
-    return result.rows.map(row => this.mapRow(row));
-  }
-
-  async findById(id: string): Promise<OwnershipCost | null> {
-    const query = 'SELECT * FROM ownership_costs WHERE id = $1';
-    const result = await this.pool.query(query, [id]);
-
-    if (result.rows.length === 0) {
-      return null;
-    }
-
-    return this.mapRow(result.rows[0]);
-  }
-
-  async findByDocumentId(documentId: string): Promise<OwnershipCost[]> {
-    const query = `
-      SELECT * FROM ownership_costs
-      WHERE document_id = $1
-      ORDER BY start_date DESC
-    `;
-
-    const result = await this.pool.query(query, [documentId]);
-    return result.rows.map(row => this.mapRow(row));
-  }
-
-  async update(id: string, data: UpdateOwnershipCostRequest): Promise<OwnershipCost | null> {
-    const fields = [];
-    const values = [];
-    let paramCount = 1;
-
-    // Build dynamic update query
-    if (data.documentId !== undefined) {
-      fields.push(`document_id = $${paramCount++}`);
-      values.push(data.documentId);
-    }
-    if (data.costType !== undefined) {
-      fields.push(`cost_type = $${paramCount++}`);
-      values.push(data.costType);
-    }
-    if (data.description !== undefined) {
-      fields.push(`description = $${paramCount++}`);
-      values.push(data.description);
-    }
-    if (data.amount !== undefined) {
-      fields.push(`amount = $${paramCount++}`);
-      values.push(data.amount);
-    }
-    if (data.interval !== undefined) {
-      fields.push(`interval = $${paramCount++}`);
-      values.push(data.interval);
-    }
-    if (data.startDate !== undefined) {
-      fields.push(`start_date = $${paramCount++}`);
-      values.push(data.startDate);
-    }
-    if (data.endDate !== undefined) {
-      fields.push(`end_date = $${paramCount++}`);
-      values.push(data.endDate);
-    }
-
-    if (fields.length === 0) {
-      return this.findById(id);
-    }
-
-    values.push(id);
-    const query = `
-      UPDATE ownership_costs
-      SET ${fields.join(', ')}
-      WHERE id = $${paramCount}
-      RETURNING *
-    `;
-
-    const result = await this.pool.query(query, values);
-
-    if (result.rows.length === 0) {
-      return null;
-    }
-
-    return this.mapRow(result.rows[0]);
-  }
-
-  async delete(id: string): Promise<boolean> {
-    const query = 'DELETE FROM ownership_costs WHERE id = $1';
-    const result = await this.pool.query(query, [id]);
-    return (result.rowCount ?? 0) > 0;
-  }
-
-  async batchInsert(
-    costs: Array<CreateOwnershipCostRequest & { userId: string }>,
-    client?: Pool
-  ): Promise<OwnershipCost[]> {
-    if (costs.length === 0) {
-      return [];
-    }
-
-    const queryClient = client || this.pool;
-    const placeholders: string[] = [];
-    const values: unknown[] = [];
-    let paramCount = 1;
-
-    costs.forEach((cost) => {
-      const costParams = [
+  async insert(cost: {
+    id: string;
+    userId: string;
+    vehicleId: string;
+    documentId?: string | null;
+    costType: OwnershipCostType;
+    amount: number;
+    description?: string | null;
+    periodStart?: string | null;
+    periodEnd?: string | null;
+    notes?: string | null;
+  }): Promise<OwnershipCost> {
+    const res = await this.db.query(
+      `INSERT INTO ownership_costs (
+        id, user_id, vehicle_id, document_id, cost_type, amount, description, period_start, period_end, notes
+      ) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10)
+      RETURNING *`,
+      [
+        cost.id,
         cost.userId,
         cost.vehicleId,
         cost.documentId ?? null,
         cost.costType,
-        cost.description ?? null,
         cost.amount,
-        cost.interval,
-        cost.startDate,
-        cost.endDate ?? null
-      ];
-
-      const placeholder = `($${paramCount++}, $${paramCount++}, $${paramCount++}, $${paramCount++}, $${paramCount++}, $${paramCount++}, $${paramCount++}, $${paramCount++}, $${paramCount++})`;
-      placeholders.push(placeholder);
-      values.push(...costParams);
-    });
-
-    const query = `
-      INSERT INTO ownership_costs (
-        user_id, vehicle_id, document_id, cost_type, description,
-        amount, interval, start_date, end_date
-      )
-      VALUES ${placeholders.join(', ')}
-      RETURNING *
-    `;
-
-    const result = await queryClient.query(query, values);
-    return result.rows.map((row: Record<string, unknown>) => this.mapRow(row));
+        cost.description ?? null,
+        cost.periodStart ?? null,
+        cost.periodEnd ?? null,
+        cost.notes ?? null,
+      ]
+    );
+    return this.mapRow(res.rows[0]);
   }
 
-  private mapRow(row: Record<string, unknown>): OwnershipCost {
-    return {
-      id: row.id as string,
-      userId: row.user_id as string,
-      vehicleId: row.vehicle_id as string,
-      documentId: row.document_id as string | undefined,
-      costType: row.cost_type as OwnershipCostType,
-      description: row.description as string | undefined,
-      amount: Number(row.amount),
-      interval: row.interval as CostInterval,
-      startDate: row.start_date as Date,
-      endDate: row.end_date as Date | undefined,
-      createdAt: row.created_at as Date,
-      updatedAt: row.updated_at as Date,
-    };
+  async findById(id: string, userId: string): Promise<OwnershipCost | null> {
+    const res = await this.db.query(
+      `SELECT * FROM ownership_costs WHERE id = $1 AND user_id = $2`,
+      [id, userId]
+    );
+    return res.rows[0] ? this.mapRow(res.rows[0]) : null;
+  }
+
+  async findByUserId(
+    userId: string,
+    filters?: { vehicleId?: string; costType?: OwnershipCostType; documentId?: string }
+  ): Promise<OwnershipCost[]> {
+    const conds: string[] = ['user_id = $1'];
+    const params: any[] = [userId];
+    let i = 2;
+
+    if (filters?.vehicleId) {
+      conds.push(`vehicle_id = $${i++}`);
+      params.push(filters.vehicleId);
+    }
+    if (filters?.costType) {
+      conds.push(`cost_type = $${i++}`);
+      params.push(filters.costType);
+    }
+    if (filters?.documentId) {
+      conds.push(`document_id = $${i++}`);
+      params.push(filters.documentId);
+    }
+
+    const sql = `SELECT * FROM ownership_costs WHERE ${conds.join(' AND ')} ORDER BY period_start DESC, created_at DESC`;
+    const res = await this.db.query(sql, params);
+    return res.rows.map(row => this.mapRow(row));
+  }
+
+  async findByVehicleId(vehicleId: string, userId: string): Promise<OwnershipCost[]> {
+    const res = await this.db.query(
+      `SELECT * FROM ownership_costs WHERE vehicle_id = $1 AND user_id = $2 ORDER BY period_start DESC, created_at DESC`,
+      [vehicleId, userId]
+    );
+    return res.rows.map(row => this.mapRow(row));
+  }
+
+  async update(
+    id: string,
+    userId: string,
+    patch: Partial<Pick<OwnershipCost, 'documentId' | 'costType' | 'amount' | 'description' | 'periodStart' | 'periodEnd' | 'notes'>>
+  ): Promise<OwnershipCost | null> {
+    const fields: string[] = [];
+    const params: any[] = [];
+    let i = 1;
+
+    if (patch.documentId !== undefined) {
+      fields.push(`document_id = $${i++}`);
+      params.push(patch.documentId);
+    }
+    if (patch.costType !== undefined) {
+      fields.push(`cost_type = $${i++}`);
+      params.push(patch.costType);
+    }
+    if (patch.amount !== undefined) {
+      fields.push(`amount = $${i++}`);
+      params.push(patch.amount);
+    }
+    if (patch.description !== undefined) {
+      fields.push(`description = $${i++}`);
+      params.push(patch.description);
+    }
+    if (patch.periodStart !== undefined) {
+      fields.push(`period_start = $${i++}`);
+      params.push(patch.periodStart);
+    }
+    if (patch.periodEnd !== undefined) {
+      fields.push(`period_end = $${i++}`);
+      params.push(patch.periodEnd);
+    }
+    if (patch.notes !== undefined) {
+      fields.push(`notes = $${i++}`);
+      params.push(patch.notes);
+    }
+
+    if (!fields.length) return this.findById(id, userId);
+
+    params.push(id, userId);
+    const sql = `UPDATE ownership_costs SET ${fields.join(', ')} WHERE id = $${i++} AND user_id = $${i++} RETURNING *`;
+    const res = await this.db.query(sql, params);
+    return res.rows[0] ? this.mapRow(res.rows[0]) : null;
+  }
+
+  async delete(id: string, userId: string): Promise<void> {
+    await this.db.query(
+      `DELETE FROM ownership_costs WHERE id = $1 AND user_id = $2`,
+      [id, userId]
+    );
   }
 }
diff --git a/backend/src/features/ownership-costs/domain/ownership-costs.service.ts b/backend/src/features/ownership-costs/domain/ownership-costs.service.ts
index 4acf5df..56f6979 100644
--- a/backend/src/features/ownership-costs/domain/ownership-costs.service.ts
+++ b/backend/src/features/ownership-costs/domain/ownership-costs.service.ts
@@ -1,199 +1,141 @@
-/**
- * @ai-summary Business logic for ownership costs feature
- * @ai-context Handles ownership cost operations and TCO aggregation
- */
-
-import { Pool } from 'pg';
-import { OwnershipCostsRepository } from '../data/ownership-costs.repository';
-import {
-  OwnershipCost,
+import { randomUUID } from 'crypto';
+import type { Pool } from 'pg';
+import type {
   CreateOwnershipCostRequest,
   UpdateOwnershipCostRequest,
+  OwnershipCost,
   OwnershipCostResponse,
-  OwnershipCostStats,
-  PAYMENTS_PER_YEAR,
-  OwnershipCostType
+  OwnershipCostType,
+  OwnershipCostStats
 } from './ownership-costs.types';
-import { logger } from '../../../core/logging/logger';
-import { VehiclesRepository } from '../../vehicles/data/vehicles.repository';
+import { OwnershipCostsRepository } from '../data/ownership-costs.repository';
+import pool from '../../../core/config/database';
 
 export class OwnershipCostsService {
-  private repository: OwnershipCostsRepository;
-  private vehiclesRepository: VehiclesRepository;
+  private readonly repo: OwnershipCostsRepository;
+  private readonly db: Pool;
 
-  constructor(pool: Pool) {
-    this.repository = new OwnershipCostsRepository(pool);
-    this.vehiclesRepository = new VehiclesRepository(pool);
+  constructor(dbPool?: Pool) {
+    this.db = dbPool || pool;
+    this.repo = new OwnershipCostsRepository(this.db);
   }
 
-  async create(data: CreateOwnershipCostRequest, userId: string): Promise<OwnershipCostResponse> {
-    logger.info('Creating ownership cost', { userId, vehicleId: data.vehicleId, costType: data.costType });
+  async createCost(userId: string, body: CreateOwnershipCostRequest): Promise<OwnershipCost> {
+    await this.assertVehicleOwnership(userId, body.vehicleId);
 
-    // Verify vehicle ownership
-    const vehicle = await this.vehiclesRepository.findById(data.vehicleId);
-    if (!vehicle) {
-      throw new Error('Vehicle not found');
-    }
-    if (vehicle.userId !== userId) {
-      throw new Error('Unauthorized');
-    }
+    const id = randomUUID();
+    const cost = await this.repo.insert({
+      id,
+      userId,
+      vehicleId: body.vehicleId,
+      documentId: body.documentId,
+      costType: body.costType,
+      amount: body.amount,
+      description: body.description,
+      periodStart: body.periodStart,
+      periodEnd: body.periodEnd,
+      notes: body.notes,
+    });
 
-    const cost = await this.repository.create({ ...data, userId });
+    return cost;
+  }
+
+  async getCost(userId: string, id: string): Promise<OwnershipCostResponse | null> {
+    const cost = await this.repo.findById(id, userId);
+    if (!cost) return null;
     return this.toResponse(cost);
   }
 
-  async getByVehicleId(vehicleId: string, userId: string): Promise<OwnershipCostResponse[]> {
-    // Verify vehicle ownership
-    const vehicle = await this.vehiclesRepository.findById(vehicleId);
-    if (!vehicle) {
-      throw new Error('Vehicle not found');
-    }
-    if (vehicle.userId !== userId) {
-      throw new Error('Unauthorized');
-    }
-
-    const costs = await this.repository.findByVehicleId(vehicleId, userId);
-    return costs.map(cost => this.toResponse(cost));
+  async getCosts(userId: string, filters?: { vehicleId?: string; costType?: OwnershipCostType; documentId?: string }): Promise<OwnershipCostResponse[]> {
+    const costs = await this.repo.findByUserId(userId, filters);
+    return costs.map(c => this.toResponse(c));
   }
 
-  async getById(id: string, userId: string): Promise<OwnershipCostResponse> {
-    const cost = await this.repository.findById(id);
-
-    if (!cost) {
-      throw new Error('Ownership cost not found');
-    }
-
-    if (cost.userId !== userId) {
-      throw new Error('Unauthorized');
-    }
-
-    return this.toResponse(cost);
+  async getCostsByVehicle(userId: string, vehicleId: string): Promise<OwnershipCostResponse[]> {
+    const costs = await this.repo.findByVehicleId(vehicleId, userId);
+    return costs.map(c => this.toResponse(c));
   }
 
-  async update(id: string, data: UpdateOwnershipCostRequest, userId: string): Promise<OwnershipCostResponse> {
-    // Verify ownership
-    const existing = await this.repository.findById(id);
-    if (!existing) {
-      throw new Error('Ownership cost not found');
-    }
-    if (existing.userId !== userId) {
-      throw new Error('Unauthorized');
-    }
+  async getVehicleOwnershipCosts(vehicleId: string, userId: string): Promise<OwnershipCostStats> {
+    const costs = await this.repo.findByVehicleId(vehicleId, userId);
 
-    const updated = await this.repository.update(id, data);
-    if (!updated) {
-      throw new Error('Update failed');
-    }
+    let totalCost = 0;
+    let insuranceCosts = 0;
+    let registrationCosts = 0;
+    let taxCosts = 0;
+    let otherCosts = 0;
 
-    return this.toResponse(updated);
-  }
+    for (const c of costs) {
+      if (c.amount === null || c.amount === undefined) continue;
+      const amount = Number(c.amount);
+      if (isNaN(amount)) {
+        throw new Error(`Invalid amount value for ownership cost ${c.id}`);
+      }
 
-  async delete(id: string, userId: string): Promise<void> {
-    // Verify ownership
-    const existing = await this.repository.findById(id);
-    if (!existing) {
-      throw new Error('Ownership cost not found');
-    }
-    if (existing.userId !== userId) {
-      throw new Error('Unauthorized');
-    }
+      totalCost += amount;
 
-    await this.repository.delete(id);
-    logger.info('Ownership cost deleted', { id, userId });
-  }
-
-  /**
-   * Get aggregated cost statistics for a vehicle
-   * Used by TCO calculation in vehicles service
-   */
-  async getVehicleCostStats(vehicleId: string, userId: string): Promise<OwnershipCostStats> {
-    const costs = await this.repository.findByVehicleId(vehicleId, userId);
-    const now = new Date();
-
-    const stats: OwnershipCostStats = {
-      insuranceCosts: 0,
-      registrationCosts: 0,
-      taxCosts: 0,
-      otherCosts: 0,
-      totalCosts: 0
-    };
-
-    for (const cost of costs) {
-      const startDate = new Date(cost.startDate);
-      const endDate = cost.endDate ? new Date(cost.endDate) : now;
-
-      // Skip future costs
-      if (startDate > now) continue;
-
-      // Calculate effective end date (either specified end, or now for ongoing costs)
-      const effectiveEnd = endDate < now ? endDate : now;
-      const monthsCovered = this.calculateMonthsBetween(startDate, effectiveEnd);
-      const normalizedCost = this.normalizeToTotal(cost.amount, cost.interval, monthsCovered);
-
-      // Type-safe key access
-      const keyMap: Record<OwnershipCostType, keyof Omit<OwnershipCostStats, 'totalCosts'>> = {
-        insurance: 'insuranceCosts',
-        registration: 'registrationCosts',
-        tax: 'taxCosts',
-        other: 'otherCosts'
-      };
-
-      const key = keyMap[cost.costType];
-      if (key) {
-        stats[key] += normalizedCost;
-      } else {
-        logger.warn('Unknown cost type in aggregation', { costType: cost.costType, costId: cost.id });
+      // Breakdown by cost type for backward compatibility
+      switch (c.costType) {
+        case 'insurance':
+          insuranceCosts += amount;
+          break;
+        case 'registration':
+          registrationCosts += amount;
+          break;
+        case 'tax':
+          taxCosts += amount;
+          break;
+        case 'inspection':
+        case 'parking':
+        case 'other':
+          otherCosts += amount;
+          break;
       }
     }
 
-    stats.totalCosts = stats.insuranceCosts + stats.registrationCosts + stats.taxCosts + stats.otherCosts;
-    return stats;
+    return {
+      totalCost,
+      recordCount: costs.length,
+      insuranceCosts,
+      registrationCosts,
+      taxCosts,
+      otherCosts
+    };
   }
 
-  /**
-   * Calculate months between two dates
-   */
-  private calculateMonthsBetween(startDate: Date, endDate: Date): number {
-    const yearDiff = endDate.getFullYear() - startDate.getFullYear();
-    const monthDiff = endDate.getMonth() - startDate.getMonth();
-    return Math.max(1, yearDiff * 12 + monthDiff);
+  // Alias for backward compatibility with vehicles service
+  async getVehicleCostStats(vehicleId: string, userId: string): Promise<OwnershipCostStats> {
+    return this.getVehicleOwnershipCosts(vehicleId, userId);
   }
 
-  /**
-   * Normalize recurring cost to total based on interval and months covered
-   */
-  private normalizeToTotal(amount: number, interval: string, monthsCovered: number): number {
-    // One-time costs are just the amount
-    if (interval === 'one_time') {
-      return amount;
-    }
+  async updateCost(userId: string, id: string, patch: UpdateOwnershipCostRequest): Promise<OwnershipCostResponse | null> {
+    const existing = await this.repo.findById(id, userId);
+    if (!existing) return null;
 
-    const paymentsPerYear = PAYMENTS_PER_YEAR[interval as keyof typeof PAYMENTS_PER_YEAR];
-    if (!paymentsPerYear) {
-      logger.warn('Invalid cost interval', { interval });
-      return 0;
-    }
+    // Convert nulls to undefined for repository compatibility
+    const cleanPatch = Object.fromEntries(
+      Object.entries(patch).map(([k, v]) => [k, v === null ? undefined : v])
+    ) as Partial<Pick<OwnershipCost, 'documentId' | 'costType' | 'amount' | 'description' | 'periodStart' | 'periodEnd' | 'notes'>>;
 
-    // Calculate total payments over the covered period
-    const yearsOwned = monthsCovered / 12;
-    const totalPayments = yearsOwned * paymentsPerYear;
-    return amount * totalPayments;
+    const updated = await this.repo.update(id, userId, cleanPatch);
+    if (!updated) return null;
+    return this.toResponse(updated);
+  }
+
+  async deleteCost(userId: string, id: string): Promise<void> {
+    await this.repo.delete(id, userId);
+  }
+
+  private async assertVehicleOwnership(userId: string, vehicleId: string) {
+    const res = await this.db.query('SELECT id FROM vehicles WHERE id = $1 AND user_id = $2', [vehicleId, userId]);
+    if (!res.rows[0]) {
+      const err: any = new Error('Vehicle not found or not owned by user');
+      err.statusCode = 403;
+      throw err;
+    }
   }
 
   private toResponse(cost: OwnershipCost): OwnershipCostResponse {
-    return {
-      id: cost.id,
-      userId: cost.userId,
-      vehicleId: cost.vehicleId,
-      documentId: cost.documentId,
-      costType: cost.costType,
-      description: cost.description,
-      amount: cost.amount,
-      interval: cost.interval,
-      startDate: cost.startDate instanceof Date ? cost.startDate.toISOString().split('T')[0] : cost.startDate as unknown as string,
-      endDate: cost.endDate ? (cost.endDate instanceof Date ? cost.endDate.toISOString().split('T')[0] : cost.endDate as unknown as string) : undefined,
-      createdAt: cost.createdAt instanceof Date ? cost.createdAt.toISOString() : cost.createdAt as unknown as string,
-      updatedAt: cost.updatedAt instanceof Date ? cost.updatedAt.toISOString() : cost.updatedAt as unknown as string,
-    };
+    return cost;
   }
 }
diff --git a/backend/src/features/ownership-costs/domain/ownership-costs.types.ts b/backend/src/features/ownership-costs/domain/ownership-costs.types.ts
index f367cc7..3108d8d 100644
--- a/backend/src/features/ownership-costs/domain/ownership-costs.types.ts
+++ b/backend/src/features/ownership-costs/domain/ownership-costs.types.ts
@@ -1,108 +1,69 @@
 /**
  * @ai-summary Type definitions for ownership-costs feature
- * @ai-context Tracks vehicle ownership costs (insurance, registration, tax, other)
+ * @ai-context Tracks vehicle ownership costs (insurance, registration, tax, inspection, parking, other)
  */
 
-// Cost types supported by ownership-costs feature
-export type OwnershipCostType = 'insurance' | 'registration' | 'tax' | 'other';
+import { z } from 'zod';
 
-// Cost interval types (one_time added for things like purchase price)
-export type CostInterval = 'monthly' | 'semi_annual' | 'annual' | 'one_time';
-
-// Payments per year for each interval type
-export const PAYMENTS_PER_YEAR: Record<CostInterval, number> = {
-  monthly: 12,
-  semi_annual: 2,
-  annual: 1,
-  one_time: 0, // Special case: calculated differently
-} as const;
+// Ownership cost types
+export type OwnershipCostType = 'insurance' | 'registration' | 'tax' | 'inspection' | 'parking' | 'other';
 
+// Database record type (camelCase for TypeScript)
 export interface OwnershipCost {
   id: string;
   userId: string;
   vehicleId: string;
   documentId?: string;
   costType: OwnershipCostType;
-  description?: string;
   amount: number;
-  interval: CostInterval;
-  startDate: Date;
-  endDate?: Date;
-  createdAt: Date;
-  updatedAt: Date;
-}
-
-export interface CreateOwnershipCostRequest {
-  vehicleId: string;
-  documentId?: string;
-  costType: OwnershipCostType;
   description?: string;
-  amount: number;
-  interval: CostInterval;
-  startDate: string; // ISO date string
-  endDate?: string;  // ISO date string
-}
-
-export interface UpdateOwnershipCostRequest {
-  documentId?: string | null;
-  costType?: OwnershipCostType;
-  description?: string | null;
-  amount?: number;
-  interval?: CostInterval;
-  startDate?: string;
-  endDate?: string | null;
-}
-
-export interface OwnershipCostResponse {
-  id: string;
-  userId: string;
-  vehicleId: string;
-  documentId?: string;
-  costType: OwnershipCostType;
-  description?: string;
-  amount: number;
-  interval: CostInterval;
-  startDate: string;
-  endDate?: string;
+  periodStart?: string;
+  periodEnd?: string;
+  notes?: string;
   createdAt: string;
   updatedAt: string;
 }
 
-// Aggregated cost statistics for TCO calculation
+// Zod schemas for validation (camelCase for API)
+export const OwnershipCostTypeSchema = z.enum(['insurance', 'registration', 'tax', 'inspection', 'parking', 'other']);
+
+export const CreateOwnershipCostSchema = z.object({
+  vehicleId: z.string().uuid(),
+  documentId: z.string().uuid().optional(),
+  costType: OwnershipCostTypeSchema,
+  amount: z.number().positive(),
+  description: z.string().max(200).optional(),
+  periodStart: z.string().optional(),
+  periodEnd: z.string().optional(),
+  notes: z.string().max(10000).optional(),
+});
+export type CreateOwnershipCostRequest = z.infer<typeof CreateOwnershipCostSchema>;
+
+export const UpdateOwnershipCostSchema = z.object({
+  documentId: z.string().uuid().nullable().optional(),
+  costType: OwnershipCostTypeSchema.optional(),
+  amount: z.number().positive().optional(),
+  description: z.string().max(200).nullable().optional(),
+  periodStart: z.string().nullable().optional(),
+  periodEnd: z.string().nullable().optional(),
+  notes: z.string().max(10000).nullable().optional(),
+});
+export type UpdateOwnershipCostRequest = z.infer<typeof UpdateOwnershipCostSchema>;
+
+// Response types
+export interface OwnershipCostResponse extends OwnershipCost {}
+
+// TCO aggregation stats
+// NOTE: Extended for backward compatibility with vehicles service
+// The spec calls for totalCost and recordCount only, but the vehicles service
+// expects breakdown by cost type. This will be cleaned up when vehicles service
+// is refactored to use the new ownership-costs table directly.
 export interface OwnershipCostStats {
-  insuranceCosts: number;
-  registrationCosts: number;
-  taxCosts: number;
-  otherCosts: number;
-  totalCosts: number;
-}
-
-// Fastify-specific types for HTTP handling
-export interface CreateOwnershipCostBody {
-  vehicleId: string;
-  documentId?: string;
-  costType: OwnershipCostType;
-  description?: string;
-  amount: number;
-  interval: CostInterval;
-  startDate: string;
-  endDate?: string;
-}
-
-export interface UpdateOwnershipCostBody {
-  documentId?: string | null;
-  costType?: OwnershipCostType;
-  description?: string | null;
-  amount?: number;
-  interval?: CostInterval;
-  startDate?: string;
-  endDate?: string | null;
-}
-
-export interface OwnershipCostParams {
-  id: string;
-}
-
-export interface VehicleParams {
-  vehicleId: string;
+  totalCost: number;
+  recordCount: number;
+  // Backward compatibility fields for vehicles service
+  insuranceCosts?: number;
+  registrationCosts?: number;
+  taxCosts?: number;
+  otherCosts?: number;
 }
diff --git a/backend/src/features/ownership-costs/index.ts b/backend/src/features/ownership-costs/index.ts
index 7b97d0e..4fefbc0 100644
--- a/backend/src/features/ownership-costs/index.ts
+++ b/backend/src/features/ownership-costs/index.ts
@@ -12,11 +12,8 @@ export type {
   UpdateOwnershipCostRequest,
   OwnershipCostResponse,
   OwnershipCostStats,
-  OwnershipCostType,
-  CostInterval
+  OwnershipCostType
 } from './domain/ownership-costs.types';
 
-export { PAYMENTS_PER_YEAR } from './domain/ownership-costs.types';
-
 // Internal: Register routes with Fastify app
-export { ownershipCostsRoutes, registerOwnershipCostsRoutes } from './api/ownership-costs.routes';
+export { ownershipCostsRoutes } from './api/ownership-costs.routes';
diff --git a/backend/src/features/ownership-costs/migrations/001_create_ownership_costs_table.sql b/backend/src/features/ownership-costs/migrations/001_create_ownership_costs_table.sql
index 5cc9749..111a5c0 100644
--- a/backend/src/features/ownership-costs/migrations/001_create_ownership_costs_table.sql
+++ b/backend/src/features/ownership-costs/migrations/001_create_ownership_costs_table.sql
@@ -1,60 +1,27 @@
 -- Migration: Create ownership_costs table
--- Issue: #15
--- Description: Store vehicle ownership costs (insurance, registration, tax, other)
--- with explicit date ranges and optional document association
+-- Issue: #29
+-- Description: Create ownership_costs table for tracking insurance, registration, tax, inspection, parking, and other costs
 
-CREATE TABLE IF NOT EXISTS ownership_costs (
+CREATE TABLE ownership_costs (
   id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
   user_id VARCHAR(255) NOT NULL,
-  vehicle_id UUID NOT NULL,
-  document_id UUID,
-  cost_type VARCHAR(50) NOT NULL,
-  description TEXT,
-  amount DECIMAL(12, 2) NOT NULL,
-  interval VARCHAR(20) NOT NULL,
-  start_date DATE NOT NULL,
-  end_date DATE,
+  vehicle_id UUID NOT NULL REFERENCES vehicles(id) ON DELETE CASCADE,
+  document_id UUID NULL REFERENCES documents(id) ON DELETE CASCADE,
+  cost_type VARCHAR(32) NOT NULL CHECK (cost_type IN ('insurance', 'registration', 'tax', 'inspection', 'parking', 'other')),
+  amount DECIMAL(10, 2) NOT NULL CHECK (amount > 0),
+  description VARCHAR(200),
+  period_start DATE,
+  period_end DATE,
+  notes TEXT,
   created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
-  updated_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
-
-  -- Foreign key to vehicles (cascade delete)
-  CONSTRAINT fk_ownership_costs_vehicle
-    FOREIGN KEY (vehicle_id)
-    REFERENCES vehicles(id)
-    ON DELETE CASCADE,
-
-  -- Foreign key to documents (set null on delete)
-  CONSTRAINT fk_ownership_costs_document
-    FOREIGN KEY (document_id)
-    REFERENCES documents(id)
-    ON DELETE SET NULL,
-
-  -- Enforce valid cost types
-  CONSTRAINT chk_ownership_costs_type
-    CHECK (cost_type IN ('insurance', 'registration', 'tax', 'other')),
-
-  -- Enforce valid intervals
-  CONSTRAINT chk_ownership_costs_interval
-    CHECK (interval IN ('monthly', 'semi_annual', 'annual', 'one_time')),
-
-  -- Enforce non-negative amounts
-  CONSTRAINT chk_ownership_costs_amount_non_negative
-    CHECK (amount >= 0),
-
-  -- Enforce end_date >= start_date when end_date is provided
-  CONSTRAINT chk_ownership_costs_date_range
-    CHECK (end_date IS NULL OR end_date >= start_date)
+  updated_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP
 );
 
--- Create indexes for common queries
-CREATE INDEX IF NOT EXISTS idx_ownership_costs_user_id ON ownership_costs(user_id);
-CREATE INDEX IF NOT EXISTS idx_ownership_costs_vehicle_id ON ownership_costs(vehicle_id);
-CREATE INDEX IF NOT EXISTS idx_ownership_costs_cost_type ON ownership_costs(cost_type);
-CREATE INDEX IF NOT EXISTS idx_ownership_costs_start_date ON ownership_costs(start_date DESC);
-CREATE INDEX IF NOT EXISTS idx_ownership_costs_document_id ON ownership_costs(document_id) WHERE document_id IS NOT NULL;
+CREATE INDEX idx_ownership_costs_user_id ON ownership_costs(user_id);
+CREATE INDEX idx_ownership_costs_vehicle_id ON ownership_costs(vehicle_id);
+CREATE INDEX idx_ownership_costs_document_id ON ownership_costs(document_id);
+CREATE INDEX idx_ownership_costs_cost_type ON ownership_costs(cost_type);
 
--- Add updated_at trigger
-DROP TRIGGER IF EXISTS update_ownership_costs_updated_at ON ownership_costs;
 CREATE TRIGGER update_ownership_costs_updated_at
   BEFORE UPDATE ON ownership_costs
   FOR EACH ROW
diff --git a/backend/src/features/ownership-costs/migrations/002_migrate_vehicle_tco_data.sql b/backend/src/features/ownership-costs/migrations/002_migrate_vehicle_tco_data.sql
deleted file mode 100644
index 9206040..0000000
--- a/backend/src/features/ownership-costs/migrations/002_migrate_vehicle_tco_data.sql
+++ /dev/null
@@ -1,73 +0,0 @@
--- Migration: Migrate existing vehicle TCO data to ownership_costs table
--- Issue: #15
--- Description: Copy insurance and registration costs from vehicles table to ownership_costs
-
--- Insert insurance costs from vehicles that have insurance data
-INSERT INTO ownership_costs (
-  user_id,
-  vehicle_id,
-  document_id,
-  cost_type,
-  description,
-  amount,
-  interval,
-  start_date,
-  end_date
-)
-SELECT
-  v.user_id,
-  v.id AS vehicle_id,
-  NULL AS document_id,
-  'insurance' AS cost_type,
-  'Migrated from vehicle record' AS description,
-  v.insurance_cost AS amount,
-  v.insurance_interval AS interval,
-  COALESCE(v.purchase_date, v.created_at::date) AS start_date,
-  NULL AS end_date
-FROM vehicles v
-WHERE v.insurance_cost IS NOT NULL
-  AND v.insurance_cost > 0
-  AND v.insurance_interval IS NOT NULL
-  AND v.is_active = true
-  AND NOT EXISTS (
-    -- Only migrate if no insurance cost already exists for this vehicle
-    SELECT 1 FROM ownership_costs oc
-    WHERE oc.vehicle_id = v.id
-      AND oc.cost_type = 'insurance'
-      AND oc.description = 'Migrated from vehicle record'
-  );
-
--- Insert registration costs from vehicles that have registration data
-INSERT INTO ownership_costs (
-  user_id,
-  vehicle_id,
-  document_id,
-  cost_type,
-  description,
-  amount,
-  interval,
-  start_date,
-  end_date
-)
-SELECT
-  v.user_id,
-  v.id AS vehicle_id,
-  NULL AS document_id,
-  'registration' AS cost_type,
-  'Migrated from vehicle record' AS description,
-  v.registration_cost AS amount,
-  v.registration_interval AS interval,
-  COALESCE(v.purchase_date, v.created_at::date) AS start_date,
-  NULL AS end_date
-FROM vehicles v
-WHERE v.registration_cost IS NOT NULL
-  AND v.registration_cost > 0
-  AND v.registration_interval IS NOT NULL
-  AND v.is_active = true
-  AND NOT EXISTS (
-    -- Only migrate if no registration cost already exists for this vehicle
-    SELECT 1 FROM ownership_costs oc
-    WHERE oc.vehicle_id = v.id
-      AND oc.cost_type = 'registration'
-      AND oc.description = 'Migrated from vehicle record'
-  );