Kintsugi Tax Calculations API

openapi: 3.0.1
info:
  title: Kintsugi Tax 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.
  - name: Transactions
    description: Committed sales transactions and credit notes.
  - name: Customers
    description: Customer records and their transactions.
  - name: Products
    description: Product records and taxability classification.
  - name: Address Validation
    description: Address search and suggestions for jurisdiction assignment.
  - name: Nexus
    description: Physical and economic nexus tracking.
  - name: Exemptions
    description: Customer tax exemptions and certificates.
  - name: Registrations
    description: State tax registrations.
  - name: Filings
    description: Prepared and submitted sales tax returns.
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'
  /transactions:
    post:
      operationId: createTransaction
      tags:
        - Transactions
      summary: Create a transaction.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/TransactionRequest'
      responses:
        '201':
          description: Transaction created.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Transaction'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/ValidationError'
    get:
      operationId: getTransactions
      tags:
        - Transactions
      summary: List transactions.
      parameters:
        - $ref: '#/components/parameters/Page'
        - $ref: '#/components/parameters/Size'
      responses:
        '200':
          description: A page of transactions.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/TransactionPage'
        '401':
          $ref: '#/components/responses/Unauthorized'
  /transactions/{id}:
    get:
      operationId: getTransactionById
      tags:
        - Transactions
      summary: Get a transaction by ID.
      parameters:
        - $ref: '#/components/parameters/Id'
      responses:
        '200':
          description: The requested transaction.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Transaction'
        '404':
          $ref: '#/components/responses/NotFound'
    patch:
      operationId: updateTransaction
      tags:
        - Transactions
      summary: Update a transaction.
      parameters:
        - $ref: '#/components/parameters/Id'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/TransactionRequest'
      responses:
        '200':
          description: Transaction updated.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Transaction'
        '404':
          $ref: '#/components/responses/NotFound'
  /transactions/external/{external_id}:
    get:
      operationId: getTransactionByExternalId
      tags:
        - Transactions
      summary: Get a transaction by external ID.
      parameters:
        - $ref: '#/components/parameters/ExternalId'
      responses:
        '200':
          description: The requested transaction.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Transaction'
        '404':
          $ref: '#/components/responses/NotFound'
  /transactions/{id}/credit-notes:
    post:
      operationId: createCreditNoteByTransactionId
      tags:
        - Transactions
      summary: Create a credit note for a transaction.
      parameters:
        - $ref: '#/components/parameters/Id'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreditNoteRequest'
      responses:
        '201':
          description: Credit note created.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Transaction'
    patch:
      operationId: updateCreditNoteByTransactionId
      tags:
        - Transactions
      summary: Update a credit note for a transaction.
      parameters:
        - $ref: '#/components/parameters/Id'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreditNoteRequest'
      responses:
        '200':
          description: Credit note updated.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Transaction'
  /customers:
    post:
      operationId: createCustomer
      tags:
        - Customers
      summary: Create a customer.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CustomerRequest'
      responses:
        '201':
          description: Customer created.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Customer'
    get:
      operationId: getCustomers
      tags:
        - Customers
      summary: List customers.
      parameters:
        - $ref: '#/components/parameters/Page'
        - $ref: '#/components/parameters/Size'
      responses:
        '200':
          description: A page of customers.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CustomerPage'
  /customers/{id}:
    get:
      operationId: getCustomerById
      tags:
        - Customers
      summary: Get a customer by ID.
      parameters:
        - $ref: '#/components/parameters/Id'
      responses:
        '200':
          description: The requested customer.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Customer'
        '404':
          $ref: '#/components/responses/NotFound'
    patch:
      operationId: updateCustomer
      tags:
        - Customers
      summary: Update a customer.
      parameters:
        - $ref: '#/components/parameters/Id'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CustomerRequest'
      responses:
        '200':
          description: Customer updated.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Customer'
  /customers/external/{external_id}:
    get:
      operationId: getCustomerByExternalId
      tags:
        - Customers
      summary: Get a customer by external ID.
      parameters:
        - $ref: '#/components/parameters/ExternalId'
      responses:
        '200':
          description: The requested customer.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Customer'
        '404':
          $ref: '#/components/responses/NotFound'
  /products:
    post:
      operationId: createProduct
      tags:
        - Products
      summary: Create a product.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ProductRequest'
      responses:
        '201':
          description: Product created.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Product'
    get:
      operationId: getProducts
      tags:
        - Products
      summary: List products.
      parameters:
        - $ref: '#/components/parameters/Page'
        - $ref: '#/components/parameters/Size'
      responses:
        '200':
          description: A page of products.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ProductPage'
  /products/{id}:
    get:
      operationId: getProductById
      tags:
        - Products
      summary: Get a product by ID.
      parameters:
        - $ref: '#/components/parameters/Id'
      responses:
        '200':
          description: The requested product.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Product'
        '404':
          $ref: '#/components/responses/NotFound'
    patch:
      operationId: updateProduct
      tags:
        - Products
      summary: Update a product.
      parameters:
        - $ref: '#/components/parameters/Id'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ProductRequest'
      responses:
        '200':
          description: Product updated.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Product'
  /products/categories:
    get:
      operationId: getProductCategories
      tags:
        - Products
      summary: List product categories.
      responses:
        '200':
          description: Available product categories used for taxability mapping.
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/ProductCategory'
  /addresses/search:
    get:
      operationId: searchAddress
      tags:
        - Address Validation
      summary: Validate and search an address.
      parameters:
        - name: street_1
          in: query
          schema:
            type: string
        - name: city
          in: query
          schema:
            type: string
        - name: state
          in: query
          schema:
            type: string
        - name: postal_code
          in: query
          schema:
            type: string
        - name: country
          in: query
          schema:
            type: string
      responses:
        '200':
          description: The validated address.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Address'
  /addresses/suggestions:
    get:
      operationId: getAddressSuggestions
      tags:
        - Address Validation
      summary: Get address suggestions.
      parameters:
        - name: query
          in: query
          schema:
            type: string
      responses:
        '200':
          description: Suggested addresses.
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Address'
  /nexus:
    get:
      operationId: getNexusForOrg
      tags:
        - Nexus
      summary: Get nexus status for the organization.
      responses:
        '200':
          description: Nexus status across jurisdictions.
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Nexus'
  /nexus/physical:
    post:
      operationId: createPhysicalNexus
      tags:
        - Nexus
      summary: Create a physical nexus.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/PhysicalNexusRequest'
      responses:
        '201':
          description: Physical nexus created.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Nexus'
    get:
      operationId: getPhysicalNexus
      tags:
        - Nexus
      summary: List physical nexus entries.
      responses:
        '200':
          description: Physical nexus entries.
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Nexus'
  /nexus/physical/{id}:
    patch:
      operationId: updatePhysicalNexus
      tags:
        - Nexus
      summary: Update a physical nexus.
      parameters:
        - $ref: '#/components/parameters/Id'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/PhysicalNexusRequest'
      responses:
        '200':
          description: Physical nexus updated.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Nexus'
    delete:
      operationId: deletePhysicalNexus
      tags:
        - Nexus
      summary: Delete a physical nexus.
      parameters:
        - $ref: '#/components/parameters/Id'
      responses:
        '204':
          description: Physical nexus deleted.
  /exemptions:
    post:
      operationId: createExemption
      tags:
        - Exemptions
      summary: Create an exemption.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ExemptionRequest'
      responses:
        '201':
          description: Exemption created.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Exemption'
    get:
      operationId: getExemptions
      tags:
        - Exemptions
      summary: List exemptions.
      parameters:
        - $ref: '#/components/parameters/Page'
        - $ref: '#/components/parameters/Size'
      responses:
        '200':
          description: A page of exemptions.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ExemptionPage'
  /exemptions/{id}:
    get:
      operationId: getExemptionById
      tags:
        - Exemptions
      summary: Get an exemption by ID.
      parameters:
        - $ref: '#/components/parameters/Id'
      responses:
        '200':
          description: The requested exemption.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Exemption'
        '404':
          $ref: '#/components/responses/NotFound'
  /exemptions/{id}/certificates:
    post:
      operationId: uploadExemptionCertificate
      tags:
        - Exemptions
      summary: Upload an exemption certificate.
      parameters:
        - $ref: '#/components/parameters/Id'
      requestBody:
        required: true
        content:
          multipart/form-data:
            schema:
              type: object
              properties:
                file:
                  type: string
                  format: binary
      responses:
        '201':
          description: Certificate uploaded.
  /exemptions/{id}/attachments:
    get:
      operationId: getAttachmentsForExemption
      tags:
        - Exemptions
      summary: Get attachments for an exemption.
      parameters:
        - $ref: '#/components/parameters/Id'
      responses:
        '200':
          description: Exemption attachments.
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Attachment'
  /registrations:
    post:
      operationId: createRegistration
      tags:
        - Registrations
      summary: Create a registration.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/RegistrationRequest'
      responses:
        '201':
          description: Registration created.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Registration'
    get:
      operationId: getRegistrations
      tags:
        - Registrations
      summary: List registrations.
      responses:
        '200':
          description: Registrations for the organization.
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Registration'
  /registrations/{id}:
    get:
      operationId: getRegistrationById
      tags:
        - Registrations
      summary: Get a registration by ID.
      parameters:
        - $ref: '#/components/parameters/Id'
      responses:
        '200':
          description: The requested registration.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Registration'
        '404':
          $ref: '#/components/responses/NotFound'
    patch:
      operationId: updateRegistration
      tags:
        - Registrations
      summary: Update a registration.
      parameters:
        - $ref: '#/components/parameters/Id'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/RegistrationRequest'
      responses:
        '200':
          description: Registration updated.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Registration'
  /registrations/{id}/deregister:
    post:
      operationId: deregisterRegistration
      tags:
        - Registrations
      summary: Deregister a registration.
      parameters:
        - $ref: '#/components/parameters/Id'
      responses:
        '200':
          description: Registration deregistered.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Registration'
  /filings:
    get:
      operationId: getFilings
      tags:
        - Filings
      summary: List filings.
      parameters:
        - $ref: '#/components/parameters/Page'
        - $ref: '#/components/parameters/Size'
      responses:
        '200':
          description: A page of filings.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/FilingPage'
  /filings/{id}:
    get:
      operationId: getFilingById
      tags:
        - Filings
      summary: Get a filing by ID.
      parameters:
        - $ref: '#/components/parameters/Id'
      responses:
        '200':
          description: The requested filing.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Filing'
        '404':
          $ref: '#/components/responses/NotFound'
  /filings/{filing_id}/transactions:
    get:
      operationId: getTransactionsByFilingId
      tags:
        - Filings
      summary: Get transactions for a filing.
      parameters:
        - name: filing_id
          in: path
          required: true
          schema:
            type: string
      responses:
        '200':
          description: Transactions included in the filing.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/TransactionPage'
  /registrations/{registration_id}/filings:
    get:
      operationId: getFilingsByRegistrationId
      tags:
        - Filings
      summary: Get filings for a registration.
      parameters:
        - name: registration_id
          in: path
          required: true
          schema:
            type: string
      responses:
        '200':
          description: Filings for the registration.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/FilingPage'
components:
  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.
  parameters:
    Id:
      name: id
      in: path
      required: true
      schema:
        type: string
    ExternalId:
      name: external_id
      in: path
      required: true
      schema:
        type: string
    Page:
      name: page
      in: query
      schema:
        type: integer
        default: 1
    Size:
      name: size
      in: query
      schema:
        type: integer
        default: 50
  responses:
    Unauthorized:
      description: Missing or invalid API key or organization ID.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    NotFound:
      description: Resource not found.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    ValidationError:
      description: Request validation failed.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  schemas:
    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
    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
    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
    TaxItemEstimate:
      type: object
      properties:
        jurisdiction:
          type: string
        jurisdiction_type:
          type: string
        tax_rate:
          type: string
        tax_amount:
          type: string
    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'
    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'
    TransactionRequest:
      type: object
      properties:
        external_id:
          type: string
        date:
          type: string
          format: date-time
        currency:
          type: string
        status:
          type: string
        external_customer_id:
          type: string
        addresses:
          type: array
          items:
            $ref: '#/components/schemas/Address'
        transaction_items:
          type: array
          items:
            $ref: '#/components/schemas/TransactionItemEstimate'
      required:
        - external_id
        - date
        - currency
    Transaction:
      allOf:
        - $ref: '#/components/schemas/TransactionRequest'
        - type: object
          properties:
            id:
              type: string
            total_tax_amount_calculated:
              type: string
            taxable_amount:
              type: string
            created_at:
              type: string
              format: date-time
            updated_at:
              type: string
              format: date-time
    TransactionPage:
      $ref: '#/components/schemas/Page'
    CreditNoteRequest:
      type: object
      properties:
        external_id:
          type: string
        date:
          type: string
          format: date-time
        amount:
          type: number
        reason:
          type: string
    CustomerRequest:
      type: object
      properties:
        external_id:
          type: string
        name:
          type: string
        email:
          type: string
        addresses:
          type: array
          items:
            $ref: '#/components/schemas/Address'
    Customer:
      allOf:
        - $ref: '#/components/schemas/CustomerRequest'
        - type: object
          properties:
            id:
              type: string
            created_at:
              type: string
              format: date-time
    CustomerPage:
      $ref: '#/components/schemas/Page'
    ProductRequest:
      type: object
      properties:
        external_id:
          type: string
        name:
          type: string
        description:
          type: string
        category:
          type: string
        subcategory:
          type: string
        tax_code:
          type: string
    Product:
      allOf:
        - $ref: '#/components/schemas/ProductRequest'
        - type: object
          properties:
            id:
              type: string
    ProductPage:
      $ref: '#/components/schemas/Page'
    ProductCategory:
      type: object
      properties:
        category:
          type: string
        subcategory:
          type: string
        tax_code:
          type: string
        description:
          type: string
    Nexus:
      type: object
      properties:
        id:
          type: string
        state:
          type: string
        country:
          type: string
        nexus_type:
          type: string
          enum:
            - PHYSICAL
            - ECONOMIC
        status:
          type: string
        registration_id:
          type: string
    PhysicalNexusRequest:
      type: object
      properties:
        state:
          type: string
        country:
          type: string
        start_date:
          type: string
          format: date
        end_date:
          type: string
          format: date
      required:
        - state
    Exemption:
      type: object
      properties:
        id:
          type: string
        external_customer_id:
          type: string
        state:
          type: string
        exemption_type:
          type: string
        status:
          type: string
        valid_from:
          type: string
          format: date
        valid_to:
          type: string
          format: date
    ExemptionRequest:
      type: object
      properties:
        external_customer_id:
          type: string
        state:
          type: string
        exemption_type:
          type: string
        valid_from:
          type: string
          format: date
        valid_to:
          type: string
          format: date
      required:
        - external_customer_id
        - state
    ExemptionPage:
      $ref: '#/components/schemas/Page'
    Attachment:
      type: object
      properties:
        id:
          type: string
        filename:
          type: string
        url:
          type: string
        content_type:
          type: string
    Registration:
      type: object
      properties:
        id:
          type: string
        state:
          type: string
        country:
          type: string
        registration_number:
          type: string
        status:
          type: string
        effective_date:
          type: string
          format: date
        filing_frequency:
          type: string
    RegistrationRequest:
      type: object
      properties:
        state:
          type: string
        country:
          type: string
        effective_date:
          type: string
          format: date
      required:
        - state
    Filing:
      type: object
      properties:
        id:
          type: string
        registration_id:
          type: string
        state:
          type: string
        period_start:
          type: string
          format: date
        period_end:
          type: string
          format: date
        due_date:
          type: string
          format: date
        status:
          type: string
        total_tax_due:
          type: string
        filed_at:
          type: string
          format: date-time
    FilingPage:
      $ref: '#/components/schemas/Page'
    Page:
      type: object
      properties:
        items:
          type: array
          items:
            type: object
        total:
          type: integer
        page:
          type: integer
        size:
          type: integer
        pages:
          type: integer
    Error:
      type: object
      properties:
        detail:
          type: string
        status_code:
          type: integer