Create Calculations

Get tax information for a given product and address

POST /tax/calculations

cURL

basic

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_line_1": "4 Privet Drive",
      "address_city": "Little Whinging",
      "address_province": "CA",
      "address_postal_code": "90210",
      "address_country": "US",
      "address_type": "shipping"
    }
  },
  "order_details": {
    "customer_currency_code": "USD",
    "tax_included_in_amount": false,
    "line_items": [
      {
        "reference_product_id": "wand_elder_12",
        "amount": 10000,
        "quantity": 1
      }
    ]
  }
}
'

200

basic

{
  "testmode": true,
  "id": "calc_1783369478354d32be1ac-066b-49b1-a952-3e45e640c49c",
  "object": "tax.calculation",
  "customer_currency_code": "USD",
  "line_items": [
    {
      "line_item_id": "li_1783369478353396a9168-1972-4798-80cb-536d96c0cc5a",
      "product": {
        "reference_line_item_id": "",
        "reference_product_id": "wand_elder_12",
        "reference_product_name": "Elder Wand",
        "product_tax_code": "GENERAL_MERCHANDISE"
      },
      "tax_jurisdictions": [
        {
          "tax_rate": 0.0725,
          "rate_type": "general state sales tax",
          "jurisdiction_name": "California",
          "fee_amount": 0,
          "note": "RATE_FRAC"
        },
        {
          "tax_rate": 0.025,
          "rate_type": "general county local sales tax",
          "jurisdiction_name": "Los Angeles",
          "fee_amount": 0,
          "note": "RATE_FRAC"
        }
      ],
      "tax_amount": 975,
      "amount_excluding_tax": 10000,
      "amount_including_tax": 10975,
      "quantity": 1
    }
  ],
  "total_tax_amount": 975,
  "tax_included_in_amount": false,
  "total_amount_excluding_tax": 10000,
  "total_amount_including_tax": 10975,
  "expires_at": 1783455878
}

Get tax information for a given product and address

In this version, line item amount is the total for the line (not per-unit) in the currency’s smallest unit — quantity is record-keeping only and does not affect the taxable base. Per-unit pricing starts in 2026-01-01.

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. Jurisdictions whose rate applies to only part of the amount carry a note value other than RATE_FRAC, such as PROGRESSIVE_RATE.

cURL Header Example

Always set an API version — pass X-API-Version explicitly (recommended), or configure a default version on your account. Requests with neither fall back to 2024-09-01:

curl --request POST \
  --url https://api.numeralhq.com/tax/calculations \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'X-API-Version: 2024-09-01' \
  --data '{ ... }'

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: 2024-09-01 · 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, but an account default set to a newer version takes precedence over that fallback.

Available options: 2024-09-01

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

Optional, but relevant for tax collection in certain jurisdictions. The address that a product is shipped from.

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

Response

200

application/json

Calculate response

id · string

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

Example:

"calc_1783369478354d32be1ac-066b-49b1-a952-3e45e640c49c"

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"

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

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