> ## Documentation Index > Fetch the complete documentation index at: https://docs.montereyfinancial.dev/llms.txt > Use this file to discover all available pages before exploring further. # Reverse a payment your organization posted > Reverses a payment posted through this API. Requires an `Idempotency-Key` header; replaying the same key and body returns the original response. Returns 201 when reversed and 202 when the outcome is still being confirmed (`reversal_pending`). ## OpenAPI ````yaml /api-reference/external_api.openapi.json post /v1/payments/{payment_id}/reversal openapi: 3.1.0 info: title: Monterey Client API description: >- Org-scoped, token-authenticated account, borrower, and payment endpoints for Monterey Financial clients. version: 1.0.0 servers: - url: https://api.montereyfinancial.app description: Production security: - BearerToken: [] tags: - name: Authentication description: Exchange API keys for access tokens. - name: Organizations description: Organizations visible to the API key. - name: Persons description: Borrowers visible through in-scope accounts. - name: Accounts description: Servicing accounts and identifier lookups. - name: Transactions description: Account money-movement history. - name: Payment Methods description: Stored payment instruments. - name: Autopay description: Recurring payment schedules. paths: /v1/payments/{payment_id}/reversal: post: tags: - External Payments summary: Reverse a payment your organization posted description: >- Reverses a payment posted through this API. Requires an `Idempotency-Key` header; replaying the same key and body returns the original response. Returns 201 when reversed and 202 when the outcome is still being confirmed (`reversal_pending`). operationId: reverse_external_payment_v1_payments__payment_id__reversal_post parameters: - name: payment_id in: path required: true schema: type: string title: Payment Id - name: Idempotency-Key in: header required: true schema: type: string minLength: 1 maxLength: 255 title: Idempotency-Key requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/ExternalPaymentReversalCreate' responses: '201': description: Successful Response content: application/json: schema: $ref: '#/components/schemas/ExternalPaymentOut' '202': description: Outcome not yet confirmed (`reversal_pending`). content: application/json: schema: $ref: '#/components/schemas/ExternalPaymentOut' '401': description: Missing or invalid access token. '403': description: Authenticated token lacks the required scope (`insufficient_scope`). content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '404': description: Account or payment not in scope or does not exist. '409': description: >- `payment_not_reversible` (only `posted` payments can be reversed), `idempotency_conflict` or `idempotency_in_progress`. '422': description: Invalid request or a rejected reversal (`omega_rejected`). '503': description: Payment reversal is temporarily unavailable. security: - BearerToken: [] components: schemas: ExternalPaymentReversalCreate: properties: reason: type: string maxLength: 200 minLength: 1 title: Reason description: Why the payment is reversed. is_nsf: type: boolean title: Is Nsf description: Reverse as NSF (returned funds). default: false additionalProperties: false type: object required: - reason title: ExternalPaymentReversalCreate description: Request body for reversing a payment your organization posted. ExternalPaymentOut: properties: payment_id: type: string title: Payment Id description: Monterey payment ID. account_id: type: string title: Account Id description: The account the payment was posted to. amount_cents: type: integer title: Amount Cents description: Payment amount, in integer cents. payment_method: type: string title: Payment Method description: How the payment was collected. check_number: anyOf: - type: integer - type: 'null' title: Check Number description: Check number, when applicable. status: type: string title: Status description: >- `pending`, `posted`, `pending_confirmation`, `reversal_pending`, `reversed` or `failed`. effective_date: anyOf: - type: string format: date - type: 'null' title: Effective Date description: Date the payment applies. external_reference: anyOf: - type: string - type: 'null' title: External Reference description: Your own reference. memo: anyOf: - type: string - type: 'null' title: Memo description: Free-text note. reference_number: anyOf: - type: integer - type: 'null' title: Reference Number description: Reference number of the posted payment. posted_at: anyOf: - type: string format: date-time - type: 'null' title: Posted At description: When it was posted. reversal: anyOf: - $ref: '#/components/schemas/ReversalOut' - type: 'null' description: Reversal details; null unless the payment was reversed. type: object required: - payment_id - account_id - amount_cents - payment_method - check_number - status - effective_date - external_reference - memo - reference_number - posted_at - reversal title: ExternalPaymentOut description: A payment an organization posted to one of its accounts. ErrorResponse: properties: detail: $ref: '#/components/schemas/ErrorBody' type: object required: - detail title: ErrorResponse description: Standard error envelope. Branch on `detail.error_code`. ReversalOut: properties: reversed_at: anyOf: - type: string format: date-time - type: 'null' title: Reversed At description: When it was reversed. reason: anyOf: - type: string - type: 'null' title: Reason description: Reason given for the reversal. is_nsf: anyOf: - type: boolean - type: 'null' title: Is Nsf description: Whether it was reversed as NSF. reference_number: anyOf: - type: integer - type: 'null' title: Reference Number description: Reference number of the reversal. reversed_by: anyOf: - type: string - type: 'null' title: Reversed By description: Who reversed the payment. type: object required: - reversed_at - reason - is_nsf - reference_number - reversed_by title: ReversalOut description: Reversal details of a payment that has been (or is being) reversed. ErrorBody: properties: error_code: type: string title: Error Code type: object required: - error_code title: ErrorBody description: Standard error body. Branch on `error_code`. securitySchemes: BearerToken: type: http description: Short-lived access token minted by POST /v1/oauth/token. scheme: bearer bearerFormat: JWT ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.