Numeral Tax Calculations API

openapi: 3.0.1
info:
  title: Numeral Customers Tax Calculations API
  description: REST API for the Numeral (Numeral HQ) sales-tax compliance platform. Calculate real-time sales tax by customer location, record transactions and refunds, and manage products and customers. Registrations, nexus monitoring, filing, and remittance are delivered as managed platform services on top of the data captured through this API. Not affiliated with Numeral (numeral.io), an unrelated payment operations company.
  termsOfService: https://www.numeral.com/terms
  contact:
    name: Numeral Support
    url: https://www.numeral.com/
  version: '2026-03-01'
servers:
- url: https://api.numeralhq.com
  description: Numeral production API
security:
- bearerAuth: []
tags:
- name: Tax Calculations
paths:
  /tax/calculations:
    post:
      operationId: createCalculation
      tags:
      - Tax Calculations
      summary: Get tax information for a given product and address or IP.
      parameters:
      - $ref: '#/components/parameters/ApiVersion'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CalculationRequest'
      responses:
        '200':
          description: Calculated tax for the supplied order.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CalculationResponse'
  /tax/platform_calculations:
    post:
      operationId: createPlatformCalculation
      tags:
      - Tax Calculations
      summary: Calculate tax for marketplace / platform transactions on behalf of a merchant.
      parameters:
      - $ref: '#/components/parameters/ApiVersion'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CalculationRequest'
      responses:
        '200':
          description: Calculated tax for the platform order.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CalculationResponse'
components:
  schemas:
    CalculationResponse:
      type: object
      properties:
        id:
          type: string
        object:
          type: string
        customer_currency_code:
          type: string
        line_items:
          type: array
          items:
            type: object
            properties:
              reference_product_id:
                type: string
              tax_amount:
                type: integer
              taxable_amount:
                type: integer
        total_tax_amount:
          type: integer
        total_amount_excluding_tax:
          type: integer
        total_amount_including_tax:
          type: integer
        expires_at:
          type: string
          format: date-time
        testmode:
          type: boolean
        address_resolution_status:
          type: string
        address_used:
          $ref: '#/components/schemas/Address'
    LineItem:
      type: object
      properties:
        reference_product_id:
          type: string
        amount:
          type: integer
          description: Line amount in the smallest currency unit (e.g., cents).
        quantity:
          type: integer
        product_category:
          type: string
    CalculationRequest:
      type: object
      properties:
        customer:
          type: object
          properties:
            reference_customer_id:
              type: string
            customer_address:
              $ref: '#/components/schemas/Address'
            ip_address:
              type: string
        origin_address:
          $ref: '#/components/schemas/Address'
        order_details:
          type: object
          properties:
            customer_currency_code:
              type: string
            line_items:
              type: array
              items:
                $ref: '#/components/schemas/LineItem'
        metadata:
          type: object
          additionalProperties: true
    Address:
      type: object
      properties:
        line_1:
          type: string
        line_2:
          type: string
        city:
          type: string
        state:
          type: string
        postal_code:
          type: string
        country:
          type: string
  parameters:
    ApiVersion:
      name: X-API-Version
      in: header
      required: false
      schema:
        type: string
        enum:
        - '2026-03-01'
        - '2026-01-01'
        - '2025-05-12'
        - '2024-09-01'
        default: '2024-09-01'
      description: API version. Defaults to 2024-09-01 when omitted.
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: Provide your Numeral API key as a Bearer token in the Authorization header.