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 3108d8d..2264728 100644
--- a/backend/src/features/ownership-costs/domain/ownership-costs.types.ts
+++ b/backend/src/features/ownership-costs/domain/ownership-costs.types.ts
@@ -50,8 +50,8 @@ export const UpdateOwnershipCostSchema = z.object({
 });
 export type UpdateOwnershipCostRequest = z.infer<typeof UpdateOwnershipCostSchema>;
 
-// Response types
-export interface OwnershipCostResponse extends OwnershipCost {}
+// Response type (alias to OwnershipCost)
+export type OwnershipCostResponse = OwnershipCost;
 
 // TCO aggregation stats
 // NOTE: Extended for backward compatibility with vehicles service