Kintsugi Tax Estimation API

openapi: 3.0.1
info:
  title: Kintsugi Tax Address Validation Tax Estimation API
  description: REST API for the Kintsugi AI sales tax compliance and automation platform. Calculate US sales tax, VAT, and GST; sync transactions, products, and customers; validate addresses; manage physical nexus, exemptions, and registrations; and retrieve automated filings. Authentication uses an API key supplied in the x-api-key header together with the x-organization-id header identifying the organization. Endpoints, fields, and schemas in this document reflect Kintsugi's public API reference at docs.trykintsugi.com and are not exhaustive; consult the provider documentation for the authoritative contract.
  termsOfService: https://www.trykintsugi.com/terms-of-service
  contact:
    name: Kintsugi Support
    url: https://www.trykintsugi.com/support
  version: '1.0'
servers:
- url: https://api.trykintsugi.com/v1
  description: Kintsugi production API base URL
security:
- ApiKeyAuth: []
  OrganizationId: []
tags:
- name: Tax Estimation
  description: Real-time sales tax, VAT, and GST estimation.
paths:
  /tax/estimate:
    post:
      operationId: estimateTax
      tags:
      - Tax Estimation
      summary: Estimate tax for a transaction.
      description: Calculates sales tax, VAT, or GST for a prospective transaction before payment is collected. Returns a jurisdiction-level breakdown, the taxable amount, the effective tax rate, and whether an active registration exists, without persisting a transaction record.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/TransactionEstimateRequest'
      responses:
        '200':
          description: Tax estimate calculated.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/TransactionEstimateResponse'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/ValidationError'
components:
  schemas:
    TransactionEstimateRequest:
      type: object
      properties:
        external_id:
          type: string
        date:
          type: string
          format: date-time
        currency:
          type: string
          example: USD
        description:
          type: string
        marketplace:
          type: boolean
          default: false
        customer:
          $ref: '#/components/schemas/CustomerRequest'
        addresses:
          type: array
          items:
            $ref: '#/components/schemas/Address'
        transaction_items:
          type: array
          items:
            $ref: '#/components/schemas/TransactionItemEstimate'
      required:
      - external_id
      - date
      - currency
      - addresses
      - transaction_items
    TransactionItemEstimate:
      type: object
      properties:
        external_id:
          type: string
        external_product_id:
          type: string
        date:
          type: string
          format: date-time
        amount:
          type: number
        quantity:
          type: number
          default: 1
        product_name:
          type: string
        product_category:
          type: string
        product_subcategory:
          type: string
        exempt:
          type: boolean
          default: false
      required:
      - amount
      - date
    Address:
      type: object
      properties:
        type:
          type: string
          enum:
          - SHIP_TO
          - BILL_TO
        street_1:
          type: string
        street_2:
          type: string
        city:
          type: string
        county:
          type: string
        state:
          type: string
        postal_code:
          type: string
        country:
          type: string
        full_address:
          type: string
      required:
      - postal_code
      - country
    TransactionEstimateResponse:
      type: object
      properties:
        external_id:
          type: string
        date:
          type: string
          format: date-time
        currency:
          type: string
        total_tax_amount_calculated:
          type: string
        taxable_amount:
          type: string
        tax_rate_calculated:
          type: string
        has_active_registration:
          type: boolean
        addresses:
          type: array
          items:
            $ref: '#/components/schemas/Address'
        transaction_items:
          type: array
          items:
            $ref: '#/components/schemas/TransactionItemEstimateResponse'
    CustomerRequest:
      type: object
      properties:
        external_id:
          type: string
        name:
          type: string
        email:
          type: string
        addresses:
          type: array
          items:
            $ref: '#/components/schemas/Address'
    TransactionItemEstimateResponse:
      allOf:
      - $ref: '#/components/schemas/TransactionItemEstimate'
      - type: object
        properties:
          tax_amount:
            type: string
          taxable_amount:
            type: string
          tax_rate:
            type: string
          exempt_reason:
            type: string
          tax_items:
            type: array
            items:
              $ref: '#/components/schemas/TaxItemEstimate'
    TaxItemEstimate:
      type: object
      properties:
        jurisdiction:
          type: string
        jurisdiction_type:
          type: string
        tax_rate:
          type: string
        tax_amount:
          type: string
    Error:
      type: object
      properties:
        detail:
          type: string
        status_code:
          type: integer
  responses:
    ValidationError:
      description: Request validation failed.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    Unauthorized:
      description: Missing or invalid API key or organization ID.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  securitySchemes:
    ApiKeyAuth:
      type: apiKey
      in: header
      name: x-api-key
      description: API key generated in the Kintsugi dashboard.
    OrganizationId:
      type: apiKey
      in: header
      name: x-organization-id
      description: Identifier of the organization the request acts on behalf of.