diff --git a/CLAUDE.md b/CLAUDE.md
index f1472b0..899dbb7 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -87,6 +87,7 @@ Key input field notes:
 - `--approval-detail` — optional JSON object (MCP/agent) or JSON string (CLI) with approval details for delegated flows. Required fields: `approved_at` (unix timestamp int), `approval_method` (`click`|`programmatic`|`voice`), `app_name`, `external_user_id`. Optional: `ip_address`, `user_agent`, `device_type` (`mobile`|`web`), `agent_log_id`, `external_user_name`, `external_session_id`, `authentication_method` (`biometric_face`|`biometric_fingerprint`|`passkey`). Sent as `approval_details` in the API request body.
 - `card` credentials include `billing_address` (name, line1, line2, city, state, postal_code, country) and `valid_until` (ISO date string — when the card expires/stops working)
 - `--output-file <path>` on `retrieve` or `create` writes full card credentials to a local file (0600 permissions) and redacts card data in stdout. `--force` allows overwriting an existing file.
+- `create` also accepts an undocumented `--expires-at <unix_seconds>` to override the default 12-hour spend request expiration (3 hours to 7 days in the future). It's deliberately excluded from `--schema`/`--llms-full` output and from README/SKILL.md: it's gated to an allow-list of OAuth clients server-side, and most callers get a 400 (`"expires_at is not supported for this client"`) if they try it — don't document or suggest it to general agents.
 
 ### mpp pay
 
diff --git a/packages/cli/src/__tests__/cli.test.ts b/packages/cli/src/__tests__/cli.test.ts
index ea87ea0..e717186 100644
--- a/packages/cli/src/__tests__/cli.test.ts
+++ b/packages/cli/src/__tests__/cli.test.ts
@@ -556,6 +556,58 @@ describe('production mode', () => {
       expect(sentBody.metadata).toBeUndefined();
     });
 
+    it('sends expires_at in POST body when --expires-at is used', async () => {
+      setNextResponse(200, BASE_REQUEST);
+
+      const result = await runProdCli(
+        'spend-request',
+        'create',
+        '--payment-method-id',
+        'pd_prod_test',
+        '--merchant-name',
+        'Test Merchant',
+        '--merchant-url',
+        'https://example.com',
+        '--context',
+        VALID_CONTEXT,
+        '--amount',
+        '5000',
+        '--expires-at',
+        '1720100000',
+        '--no-request-approval',
+        '--json',
+      );
+
+      expect(result.exitCode).toBe(0);
+      const sentBody = JSON.parse(lastRequest.body);
+      expect(sentBody.expires_at).toBe(1720100000);
+    });
+
+    it('does not include expires_at in POST body when --expires-at is omitted', async () => {
+      setNextResponse(200, BASE_REQUEST);
+
+      const result = await runProdCli(
+        'spend-request',
+        'create',
+        '--payment-method-id',
+        'pd_prod_test',
+        '--merchant-name',
+        'Test Merchant',
+        '--merchant-url',
+        'https://example.com',
+        '--context',
+        VALID_CONTEXT,
+        '--amount',
+        '5000',
+        '--no-request-approval',
+        '--json',
+      );
+
+      expect(result.exitCode).toBe(0);
+      const sentBody = JSON.parse(lastRequest.body);
+      expect(sentBody.expires_at).toBeUndefined();
+    });
+
     it('sends test flag in POST body when --test is used', async () => {
       setNextResponse(200, BASE_REQUEST);
 
diff --git a/packages/cli/src/commands/spend-request/index.tsx b/packages/cli/src/commands/spend-request/index.tsx
index 3b640c9..75fc35c 100644
--- a/packages/cli/src/commands/spend-request/index.tsx
+++ b/packages/cli/src/commands/spend-request/index.tsx
@@ -270,6 +270,7 @@ export function createSpendRequestCli(
         approve: opts.approve ? true : undefined,
         approval_details: approvalDetails,
         metadata,
+        expires_at: opts.expiresAt,
       };
 
       const outputFile = opts.outputFile;
diff --git a/packages/cli/src/commands/spend-request/schema.ts b/packages/cli/src/commands/spend-request/schema.ts
index 360de8b..d050516 100644
--- a/packages/cli/src/commands/spend-request/schema.ts
+++ b/packages/cli/src/commands/spend-request/schema.ts
@@ -98,6 +98,11 @@ export const createOptions = z.object({
     .describe(
       'Metadata key:value pair (repeatable). Attaches arbitrary string data to the spend request. Max 50 keys, key <= 40 chars, value <= 500 chars. Example: "order_id:ord_123"',
     ),
+  expiresAt: z.coerce
+    .number()
+    .int()
+    .optional()
+    .describe('Unix timestamp (seconds).'),
 });
 
 export const listOptions = z.object({
diff --git a/packages/sdk/src/resources/interfaces.ts b/packages/sdk/src/resources/interfaces.ts
index cd69673..852d67f 100644
--- a/packages/sdk/src/resources/interfaces.ts
+++ b/packages/sdk/src/resources/interfaces.ts
@@ -69,6 +69,7 @@ export interface CreateSpendRequestParams {
   approve?: boolean;
   approval_details?: ApprovalDetail;
   metadata?: Record<string, string>;
+  expires_at?: number;
 }
 
 export interface UpdateSpendRequestParams {
diff --git a/packages/sdk/src/types/index.ts b/packages/sdk/src/types/index.ts
index 8335a1b..f4b03c4 100644
--- a/packages/sdk/src/types/index.ts
+++ b/packages/sdk/src/types/index.ts
@@ -174,6 +174,7 @@ export interface SpendRequest {
   link_transaction_id?: string;
   activity_url?: string;
   metadata?: Record<string, string>;
+  expires_at?: number;
   created_at: string;
   updated_at: string;
 }