openapi: 3.1.0
info:
  title: HMRC VAT (Making Tax Digital) Liabilities 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: Liabilities
  description: VAT financial liabilities
paths:
  /organisations/vat/{vrn}/liabilities:
    get:
      operationId: getVatLiabilities
      summary: Retrieve VAT liabilities
      description: Retrieves VAT financial liabilities owed by the business to HMRC including amounts due, outstanding balances, and due dates.
      tags:
      - Liabilities
      parameters:
      - name: vrn
        in: path
        required: true
        schema:
          type: string
          pattern: ^\d{9}$
      - name: from
        in: query
        required: true
        schema:
          type: string
          format: date
      - name: to
        in: query
        required: true
        schema:
          type: string
          format: date
      - name: Authorization
        in: header
        required: true
        schema:
          type: string
      responses:
        '200':
          description: Liabilities returned
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/LiabilitiesResponse'
components:
  schemas:
    VatLiability:
      type: object
      properties:
        taxPeriod:
          type: object
          properties:
            from:
              type: string
              format: date
            to:
              type: string
              format: date
        type:
          type: string
          description: Liability type (e.g., "VAT Return Debit Charge")
        originalAmount:
          type: number
          description: Original liability amount in GBP
        outstandingAmount:
          type: number
          description: Outstanding balance in GBP
        due:
          type: string
          format: date
          description: Payment due date
    LiabilitiesResponse:
      type: object
      properties:
        liabilities:
          type: array
          items:
            $ref: '#/components/schemas/VatLiability'
  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