diff --git a/backend/src/features/subscriptions/domain/subscriptions.types.ts b/backend/src/features/subscriptions/domain/subscriptions.types.ts
index 7c34020..298fe9b 100644
--- a/backend/src/features/subscriptions/domain/subscriptions.types.ts
+++ b/backend/src/features/subscriptions/domain/subscriptions.types.ts
@@ -19,7 +19,7 @@ export type DonationStatus = 'pending' | 'succeeded' | 'failed' | 'canceled';
 export interface Subscription {
   id: string;
   userId: string;
-  stripeCustomerId: string;
+  stripeCustomerId: string | null;
   stripeSubscriptionId?: string;
   tier: SubscriptionTier;
   billingCycle?: BillingCycle;
@@ -74,7 +74,7 @@ export interface CreateSubscriptionRequest {
 export interface SubscriptionResponse {
   id: string;
   userId: string;
-  stripeCustomerId: string;
+  stripeCustomerId: string | null;
   stripeSubscriptionId?: string;
   tier: SubscriptionTier;
   billingCycle?: BillingCycle;
@@ -118,7 +118,7 @@ export interface CreateTierVehicleSelectionRequest {
 
 // Service layer types
 export interface UpdateSubscriptionData {
-  stripeCustomerId?: string;
+  stripeCustomerId?: string | null;
   stripeSubscriptionId?: string;
   tier?: SubscriptionTier;
   billingCycle?: BillingCycle;
diff --git a/backend/src/features/subscriptions/migrations/002_nullable_stripe_customer_id.sql b/backend/src/features/subscriptions/migrations/002_nullable_stripe_customer_id.sql
new file mode 100644
index 0000000..86dd540
--- /dev/null
+++ b/backend/src/features/subscriptions/migrations/002_nullable_stripe_customer_id.sql
@@ -0,0 +1,11 @@
+-- Migration: Make stripe_customer_id NULLABLE
+-- Removes the NOT NULL constraint that forced admin_override_ placeholder values.
+-- Admin-set subscriptions (no Stripe billing) use NULL instead of sentinel strings.
+-- PostgreSQL UNIQUE constraint allows multiple NULLs (SQL standard).
+
+-- Drop NOT NULL constraint on stripe_customer_id
+ALTER TABLE subscriptions ALTER COLUMN stripe_customer_id DROP NOT NULL;
+
+-- Clean up existing admin_override_ placeholder values to NULL
+UPDATE subscriptions SET stripe_customer_id = NULL
+WHERE stripe_customer_id LIKE 'admin_override_%';
diff --git a/frontend/src/features/subscription/types/subscription.types.ts b/frontend/src/features/subscription/types/subscription.types.ts
index f8a6ac4..045063e 100644
--- a/frontend/src/features/subscription/types/subscription.types.ts
+++ b/frontend/src/features/subscription/types/subscription.types.ts
@@ -5,7 +5,7 @@ export type SubscriptionStatus = 'active' | 'past_due' | 'canceled' | 'unpaid';
 export interface Subscription {
   id: string;
   userId: string;
-  stripeCustomerId: string;
+  stripeCustomerId: string | null;
   stripeSubscriptionId?: string;
   tier: SubscriptionTier;
   billingCycle?: BillingCycle;