openapi: 3.1.0
info:
  title: HMRC VAT (Making Tax Digital) Liabilities Obligations API
  description: The HMRC VAT Making Tax Digital (MTD) API enables VAT-registered businesses and agents to submit VAT returns, view VAT obligations, liabilities, and payments, in compliance with UK Making Tax Digital requirements. Requires OAuth 2.0 authentication and mandatory fraud prevention headers on all requests.
  version: 1.0.0
  contact:
    name: HMRC Developer Hub
    url: https://developer.service.hmrc.gov.uk/
  license:
    name: Open Government Licence v3.0
    url: https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/
servers:
- url: https://api.service.hmrc.gov.uk
  description: HMRC Production API
- url: https://test-api.service.hmrc.gov.uk
  description: HMRC Sandbox (test) environment
security:
- OAuth2UserRestricted: []
tags:
- name: Obligations
  description: VAT return filing obligations
paths:
  /organisations/vat/{vrn}/obligations:
    get:
      operationId: getVatObligations
      summary: Retrieve VAT obligations
      description: Retrieves VAT return filing obligations for the specified VAT Registration Number (VRN). Returns periods for which returns must be filed, due dates, and status (Open, Fulfilled) within the requested date range.
      tags:
      - Obligations
      parameters:
      - name: vrn
        in: path
        required: true
        schema:
          type: string
          pattern: ^\d{9}$
        description: VAT Registration Number (9 digits)
      - name: from
        in: query
        required: true
        schema:
          type: string
          format: date
        description: Obligation period start date (YYYY-MM-DD), minimum 2017-01-01
      - name: to
        in: query
        required: true
        schema:
          type: string
          format: date
        description: Obligation period end date (must be within 366 days of 'from')
      - name: status
        in: query
        required: false
        schema:
          type: string
          enum:
          - O
          - F
          - A
          description: O=Open, F=Fulfilled, A=All (default)
      - name: Authorization
        in: header
        required: true
        schema:
          type: string
        description: Bearer token (OAuth 2.0)
      - name: Gov-Client-Connection-Method
        in: header
        required: true
        schema:
          type: string
        description: Fraud prevention header – client connection method
      - name: Gov-Vendor-Version
        in: header
        required: true
        schema:
          type: string
        description: Fraud prevention header – vendor application version
      responses:
        '200':
          description: VAT obligations returned
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ObligationsResponse'
        '400':
          description: Invalid VRN or date range
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '403':
          description: Client not subscribed to MTD VAT
        '404':
          description: No obligations found
components:
  schemas:
    ObligationsResponse:
      type: object
      properties:
        obligations:
          type: array
          items:
            $ref: '#/components/schemas/Obligation'
    Obligation:
      type: object
      properties:
        periodKey:
          type: string
          description: Period identifier (e.g., "23AA")
        start:
          type: string
          format: date
          description: Obligation period start date
        end:
          type: string
          format: date
          description: Obligation period end date
        due:
          type: string
          format: date
          description: Return due date
        status:
          type: string
          enum:
          - O
          - F
          description: O=Open (not filed), F=Fulfilled (filed)
        received:
          type: string
          format: date
          description: Date return was received (populated when Fulfilled)
    Error:
      type: object
      properties:
        code:
          type: string
          description: HMRC error code
        message:
          type: string
          description: Human-readable error description
        errors:
          type: array
          items:
            type: object
            properties:
              code:
                type: string
              message:
                type: string
              path:
                type: string
  securitySchemes:
    OAuth2UserRestricted:
      type: oauth2
      description: HMRC OAuth 2.0 Authorization Code grant (user-restricted)
      flows:
        authorizationCode:
          authorizationUrl: https://api.service.hmrc.gov.uk/oauth/authorize
          tokenUrl: https://api.service.hmrc.gov.uk/oauth/token
          scopes:
            write:vat: Submit VAT returns
            read:vat: Read VAT data
externalDocs:
  description: HMRC VAT API Documentation
  url: https://developer.service.hmrc.gov.uk/api-documentation/docs/api/service/vat-api/1.0