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OpenAPI Specification

openapi: 3.2.0
info:
  title: Arc & Ledger Tax Data Tax Parameters API
  version: 1.0.3
  description: 'Authority-cited U.S. tax data: annual federal tax parameters, IRC 7503-rolled filing deadlines, the IRC 6621 quarterly interest-rate table, and reference profiles for IRS notices and tax documents. Every value carries its authority citation, official URL, and tax-year vintage. General information, not tax or legal advice for any taxpayer. Free tier: no key, 30 requests/minute per IP. Docs: https://www.arcandledger.com/developers/'
  contact:
    name: Arc & Ledger Accounting
    url: https://www.arcandledger.com/developers/
servers:
- url: https://api.arcandledger.com
tags:
- name: Tax Parameters
paths:
  /v1/tax-parameters:
    get:
      summary: All tax parameters for a vintage
      parameters:
      - $ref: '#/components/parameters/year'
      responses:
        '200':
          description: Parameters with citations
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Envelope'
        '400':
          description: Invalid year
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '404':
          description: Unknown vintage
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
      tags:
      - Tax Parameters
      operationId: getV1TaxParameters
      x-operation-id-source: derived
  /v1/tax-parameters/{id}:
    get:
      summary: One parameter by id (all effective windows)
      parameters:
      - name: id
        in: path
        required: true
        schema:
          type: string
        example: mileage.business
      - $ref: '#/components/parameters/year'
      responses:
        '200':
          description: Matching records
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Envelope'
        '404':
          description: Unknown parameter
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
      tags:
      - Tax Parameters
      operationId: getV1TaxParametersById
      x-operation-id-source: derived
components:
  parameters:
    year:
      name: year
      in: query
      required: false
      schema:
        type: integer
        example: 2026
      description: Tax-year vintage; defaults to the latest complete vintage.
  schemas:
    Error:
      type: object
      required:
      - error
      properties:
        error:
          type: object
          required:
          - code
          - status
          - message
          properties:
            code:
              type: string
            status:
              type: integer
            message:
              type: string
    Envelope:
      type: object
      required:
      - data
      - meta
      - disclaimer
      properties:
        data:
          type: object
        meta:
          type: object
          required:
          - serverVersion
          properties:
            serverVersion:
              type: string
            taxYear:
              type: integer
        disclaimer:
          type: string
  securitySchemes:
    apiKey:
      type: apiKey
      in: header
      name: X-Api-Key