Create Calculations

curl --request POST \
  --url https://api.numeralhq.com/tax/calculations \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'X-API-Version: <x-api-version>' \
  --data '
{
  "customer": {
    "address": {
      "address_city": "Nashville",
      "address_country": "US",
      "address_line_1": "123 Broadway",
      "address_postal_code": "37203",
      "address_province": "TN",
      "address_type": "billing"
    }
  },
  "metadata": {
    "payment_id": "68407cb7-e1fa-47fa-8244-bd9411d53c61"
  },
  "order_details": {
    "automatic_tax": "auto",
    "customer_currency_code": "USD",
    "line_items": [
      {
        "amount": 10000,
        "product_category": "BEVERAGES",
        "quantity": 1
      },
      {
        "amount": 10000,
        "product_category": "GENERAL_MERCHANDISE",
        "quantity": 1
      }
    ],
    "tax_included_in_amount": false
  },
  "origin_address": {
    "address_city": "Nashville",
    "address_country": "US",
    "address_line_1": "500 Church St",
    "address_line_2": "",
    "address_postal_code": "37219",
    "address_province": "TN"
  }
}
'

{
  "testmode": true,
  "id": "calc_1783369695581b8ca8647-a864-40f4-bf8a-10ff46f50856",
  "object": "tax.calculation",
  "customer_currency_code": "USD",
  "line_items": [
    {
      "line_item_id": "li_17833696955814e3b8c1c-7ca2-42d0-9f71-1fb8e7c19cd7",
      "product": {
        "reference_line_item_id": "",
        "reference_product_id": "default-beverages",
        "reference_product_name": "Default BEVERAGES Product",
        "product_tax_code": "BEVERAGES"
      },
      "tax_jurisdictions": [
        {
          "tax_rate": 0.07,
          "tax_due_decimal": 700,
          "fee_amount": 0,
          "rate_type": "GENERAL STATE SALES TAX",
          "tax_authority_name": "Tennessee",
          "tax_authority_type": "",
          "tax_type": "SALES"
        },
        {
          "tax_rate": 0.0225,
          "tax_due_decimal": 225,
          "fee_amount": 0,
          "rate_type": "GENERAL COUNTY LOCAL SALES TAX",
          "tax_authority_name": "DAVIDSON",
          "tax_authority_type": "",
          "tax_type": "SALES"
        }
      ],
      "tax_amount": 925,
      "amount_excluding_tax": 10000,
      "amount_including_tax": 10925,
      "quantity": 1
    },
    {
      "line_item_id": "li_17833696955814e3b8c1c-7ca2-42d0-9f71-1fb8e7c19cd8",
      "product": {
        "reference_line_item_id": "",
        "reference_product_id": "default-general-merchandise",
        "reference_product_name": "Default GENERAL_MERCHANDISE Product",
        "product_tax_code": "GENERAL_MERCHANDISE"
      },
      "tax_jurisdictions": [
        {
          "tax_rate": 0.07,
          "tax_due_decimal": 700,
          "fee_amount": 0,
          "rate_type": "GENERAL STATE SALES TAX",
          "tax_authority_name": "Tennessee",
          "tax_authority_type": "",
          "tax_type": "SALES"
        },
        {
          "tax_rate": 0.0225,
          "tax_due_decimal": 225,
          "fee_amount": 0,
          "rate_type": "GENERAL COUNTY LOCAL SALES TAX",
          "tax_authority_name": "DAVIDSON",
          "tax_authority_type": "",
          "tax_type": "SALES"
        }
      ],
      "tax_amount": 925,
      "amount_excluding_tax": 10000,
      "amount_including_tax": 10925,
      "quantity": 1
    }
  ],
  "total_tax_amount": 1850,
  "tax_included_in_amount": false,
  "total_amount_excluding_tax": 20000,
  "total_amount_including_tax": 21850,
  "expires_at": 1783456095,
  "metadata": {
    "payment_id": "68407cb7-e1fa-47fa-8244-bd9411d53c61"
  },
  "customer": {
    "type": "CONSUMER"
  },
  "automatic_tax": "auto",
  "address_resolution_status": "EXACT",
  "address_used": {
    "address_line_1": "123 Broadway",
    "address_city": "Nashville",
    "address_province": "TN",
    "address_postal_code": "37203",
    "address_country": "US"
  }
}

POST

tax

calculations

curl --request POST \
  --url https://api.numeralhq.com/tax/calculations \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'X-API-Version: <x-api-version>' \
  --data '
{
  "customer": {
    "address": {
      "address_city": "Nashville",
      "address_country": "US",
      "address_line_1": "123 Broadway",
      "address_postal_code": "37203",
      "address_province": "TN",
      "address_type": "billing"
    }
  },
  "metadata": {
    "payment_id": "68407cb7-e1fa-47fa-8244-bd9411d53c61"
  },
  "order_details": {
    "automatic_tax": "auto",
    "customer_currency_code": "USD",
    "line_items": [
      {
        "amount": 10000,
        "product_category": "BEVERAGES",
        "quantity": 1
      },
      {
        "amount": 10000,
        "product_category": "GENERAL_MERCHANDISE",
        "quantity": 1
      }
    ],
    "tax_included_in_amount": false
  },
  "origin_address": {
    "address_city": "Nashville",
    "address_country": "US",
    "address_line_1": "500 Church St",
    "address_line_2": "",
    "address_postal_code": "37219",
    "address_province": "TN"
  }
}
'

{
  "testmode": true,
  "id": "calc_1783369695581b8ca8647-a864-40f4-bf8a-10ff46f50856",
  "object": "tax.calculation",
  "customer_currency_code": "USD",
  "line_items": [
    {
      "line_item_id": "li_17833696955814e3b8c1c-7ca2-42d0-9f71-1fb8e7c19cd7",
      "product": {
        "reference_line_item_id": "",
        "reference_product_id": "default-beverages",
        "reference_product_name": "Default BEVERAGES Product",
        "product_tax_code": "BEVERAGES"
      },
      "tax_jurisdictions": [
        {
          "tax_rate": 0.07,
          "tax_due_decimal": 700,
          "fee_amount": 0,
          "rate_type": "GENERAL STATE SALES TAX",
          "tax_authority_name": "Tennessee",
          "tax_authority_type": "",
          "tax_type": "SALES"
        },
        {
          "tax_rate": 0.0225,
          "tax_due_decimal": 225,
          "fee_amount": 0,
          "rate_type": "GENERAL COUNTY LOCAL SALES TAX",
          "tax_authority_name": "DAVIDSON",
          "tax_authority_type": "",
          "tax_type": "SALES"
        }
      ],
      "tax_amount": 925,
      "amount_excluding_tax": 10000,
      "amount_including_tax": 10925,
      "quantity": 1
    },
    {
      "line_item_id": "li_17833696955814e3b8c1c-7ca2-42d0-9f71-1fb8e7c19cd8",
      "product": {
        "reference_line_item_id": "",
        "reference_product_id": "default-general-merchandise",
        "reference_product_name": "Default GENERAL_MERCHANDISE Product",
        "product_tax_code": "GENERAL_MERCHANDISE"
      },
      "tax_jurisdictions": [
        {
          "tax_rate": 0.07,
          "tax_due_decimal": 700,
          "fee_amount": 0,
          "rate_type": "GENERAL STATE SALES TAX",
          "tax_authority_name": "Tennessee",
          "tax_authority_type": "",
          "tax_type": "SALES"
        },
        {
          "tax_rate": 0.0225,
          "tax_due_decimal": 225,
          "fee_amount": 0,
          "rate_type": "GENERAL COUNTY LOCAL SALES TAX",
          "tax_authority_name": "DAVIDSON",
          "tax_authority_type": "",
          "tax_type": "SALES"
        }
      ],
      "tax_amount": 925,
      "amount_excluding_tax": 10000,
      "amount_including_tax": 10925,
      "quantity": 1
    }
  ],
  "total_tax_amount": 1850,
  "tax_included_in_amount": false,
  "total_amount_excluding_tax": 20000,
  "total_amount_including_tax": 21850,
  "expires_at": 1783456095,
  "metadata": {
    "payment_id": "68407cb7-e1fa-47fa-8244-bd9411d53c61"
  },
  "customer": {
    "type": "CONSUMER"
  },
  "automatic_tax": "auto",
  "address_resolution_status": "EXACT",
  "address_used": {
    "address_line_1": "123 Broadway",
    "address_city": "Nashville",
    "address_province": "TN",
    "address_postal_code": "37203",
    "address_country": "US"
  }
}

Get tax information for a given product and address.

cURL Header Example

Use X-API-Version explicitly in requests:

curl --request POST \
  --url https://api.numeralhq.com/tax/calculations \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'X-API-Version: 2026-01-01' \
  --data '{ ... }'

New in 2026-01-01:

The amount field on line items is now per-unit price (taxable base = amount x quantity).
customer.tax_ids use country-specific Stripe-style types (us_ein, eu_vat, gb_vat, …) instead of VAT/GST/EIN.
New optional top-level invalid_tax_id_customer_fallback_type ("CONSUMER"): fall back to CONSUMER treatment instead of a 400 when business tax ID validation fails.
Response tax_jurisdictions use the enhanced format below; errors use a new flat format.

(address_resolution_status, address_used, and the metadata echo already existed in 2025-05-12.)

Per-Unit Pricing

Starting with version 2026-01-01, the amount field on line items represents the per-unit price rather than the total line item value:

{
  "amount": 2500,  // $25.00 per unit
  "quantity": 3    // taxable base = $75.00
}

If you are migrating from 2025-05-12 or earlier, you must update your integration to send per-unit prices instead of total line item values.

Enhanced Tax Jurisdictions

Tax jurisdiction objects now include richer detail:

Field	Description
`tax_due_decimal`	Unrounded tax due for this jurisdiction, in the currency’s smallest unit (may be fractional; `0` for flat-fee rows — see `fee_amount`)
`tax_authority_name`	Name of the tax authority (e.g., “Tennessee”, “ALLEGHENY”)
`tax_authority_type`	Type of authority (e.g., “STATE”, “COUNTY”, “CITY”, “DISTRICT”)
`tax_type`	Type of tax: `SALES`, `USE`, `VAT`, or `GST`
`rate_type`	Descriptive rate classification (e.g., “GENERAL STATE SALES TAX”)

The jurisdiction_name and note fields from prior versions are no longer included.

Caution about simply summing tax_rate values. Each tax_rate in tax_jurisdictions is the statutory rate for that jurisdiction, and in some jurisdictions a rate applies to only part of the line item amount. Tennessee’s single article rules are the common example: local rates apply only to the first $1,600 of an item, and the 2.75% state single article rate applies only to the portion between $1,600 and $3,200. For a $10,000 item the returned rates sum to 12.25%, but the tax due is $788, an effective rate of 7.88%.Always charge the returned tax_amount (or total_tax_amount). If you need an effective rate, compute tax_amount / amount_excluding_tax from the response rather than adding up tax_rate values. The per-jurisdiction tax_due_decimal field shows how much each jurisdiction actually contributed.

Error Format

Error responses now use a flat format: { "code": number, "type": "ERROR_TYPE", "message": "..." }.

Error Codes Reference

See the complete list of error types and their meanings.

Authorizations

Authorization

string

header

required

Bearer authentication header of the form Bearer <token>, where <token> is your auth token.

Headers

X-API-Version

enum<string>

default:2026-01-01

required

The API version for this request. Always set a version: pass this header explicitly (recommended), or configure a default API version on your account and omit the header. Accounts with no configured version fall back to 2024-09-01, NOT this version.

Available options:

2026-01-01

Body

application/json

customer

object

required

Customer details. Address is required. Optionally accepts a customer ID for order tracking and exemptions.

Show child attributes

order_details

object

required

Show child attributes

origin_address

object

The address that a product is shipped from. Required at calculation time unless a default origin address is configured for the destination jurisdiction on your account — omitting it with no default configured returns a 400.

Show child attributes

metadata

object

You can store arbitrary keys and values in the metadata. At most 50 keys; each key at most 255 characters; each value must be a string of at most 255 characters (non-string values are rejected).

Show child attributes

invalid_tax_id_customer_fallback_type

enum<string>

Optional. When business tax ID validation fails, fall back to treating the customer as this type instead of returning a 400. CONSUMER is the only accepted value. Available in API version 2026-01-01 and later.

Available options:

CONSUMER

Example:

"CONSUMER"

Response

Calculate response

string

The ID of the calculation. You will use this to create a transaction.

Example:

"calc_1783369695581b8ca8647-a864-40f4-bf8a-10ff46f50856"

object

string

The type of object: tax.calculation.

Example:

"tax.calculation"

customer_currency_code

string

The ISO-4217 currency code of the transaction.

Example:

"USD"

customer

object

Customer information returned in the response. type reflects the effective customer type used for the calculation (e.g., after invalid_tax_id_customer_fallback_type is applied).

Show child attributes

automatic_tax

enum<string>

The automatic tax setting for this calculation.

Available options:

auto,

disabled

Example:

"auto"

line_items

object[]

Show child attributes

tax_included_in_amount

boolean

Example:

false

total_tax_amount

integer

Total tax to charge on this calculation, in the currency's smallest unit (rounded to an integer).

Example:

140

total_amount_excluding_tax

integer

Total sale charge excluding tax, in the currency's smallest unit (rounded to an integer).

Example:

2000

total_amount_including_tax

integer

Total sale charge plus tax, in the currency's smallest unit (rounded to an integer). What you should charge your customer.

Example:

2140

expires_at

integer

Unix timestamp in seconds at which the quoted tax rates expire — 24 hours after the calculation is created.

Example:

1714787673

testmode

boolean

True if using a production API key. False if using a test API key.

Example:

false

address_resolution_status

enum<string>

Status of address resolution for the customer address. EXACT: exact address match found, POSTAL_FALLBACK_1: used postal code fallback, POSTAL_ONLY: only postal code was used for tax calculation.

Available options:

EXACT,

POSTAL_FALLBACK_1,

POSTAL_ONLY

Example:

"EXACT"

address_used

object

The actual address used for tax calculation after resolution.

Show child attributes

metadata

object

You can store arbitrary keys and values in the metadata. At most 50 keys; each key at most 255 characters; each value must be a string of at most 255 characters (non-string values are rejected).

Show child attributes

Get Started

AI help

Integration FAQs

Essentials

Objects

API Reference

cURL Header Example

Per-Unit Pricing

Enhanced Tax Jurisdictions

Error Format

Error Codes Reference

Authorizations

Headers

Body

Response

​cURL Header Example

​Per-Unit Pricing

​Enhanced Tax Jurisdictions

​Error Format

Error Codes Reference

Authorizations

Headers

Body

Response

cURL Header Example

Per-Unit Pricing

Enhanced Tax Jurisdictions

Error Format