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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_line_1": "4 Privet Drive",
      "address_city": "Little Whining",
      "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
      }
    ]
  }
}
'
{
  "id": "calc_1726683504829b84b2ad6-a4c9-4e0e-986f-7bb3d1fb17c9",
  "object": "tax.calculation",
  "customer_currency_code": "USD",
  "line_items": [
    {
      "product": {
        "reference_product_name": "Elder Wand",
        "reference_product_id": "wand_elder_12",
        "product_tax_code": "GENERAL_MERCHANDISE"
      },
      "tax_jurisdictions": [
        {
          "tax_rate": 0.1,
          "rate_type": "SALES TAX",
          "jurisdiction_name": "California",
          "fee_amount": 0
        }
      ],
      "quantity": 1,
      "tax_amount": 1000,
      "amount_excluding_tax": 10000,
      "amount_including_tax": 11000
    }
  ],
  "tax_included_in_amount": false,
  "total_tax_amount": 1000,
  "total_amount_excluding_tax": 10000,
  "total_amount_including_tax": 11000,
  "expires_at": 1726683511,
  "testmode": true,
  "address_resolution_status": "EXACT",
  "address_used": {
    "address_line_1": "4 Privet Drive",
    "address_city": "Little Whinging",
    "address_province": "CA",
    "address_postal_code": "90210",
    "address_country": "US"
  }
}
Get tax information for a given product and address or IP.
Required from 2025-05-12+:
  • The origin_address field is required for all calculations starting from API version 2025-05-12. Ensure you provide an origin address or have a default address configured.
  • The automatic_tax field in order_details is required starting from API version 2025-05-12. Use "auto" to enable automatic tax calculation or "disabled" to return zero tax rates.
Note: The address_type field is only valid on customer.address and will be silently rejected if used on origin_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: 2026-03-01' \
  --data '{ ... }'
New in 2026-03-01: You can now provide customer.ip instead of (or in addition to) customer.address for IP-based tax resolution.
Inherited from 2026-01-01: The amount field on line items is per-unit price (taxable base = amount x quantity). Responses include address_resolution_status, address_used, and enhanced tax_jurisdictions fields (tax_authority_name, tax_authority_type, tax_type, tax_due_decimal).

​
IP-Based Resolution

Instead of providing a full customer address, you can pass an IP address and we’ll resolve it to a taxable location: 
{
  "customer": {
    "type": "CONSUMER",
    "ip": {
      "value": "217.217.113.167",
      "resolution": "strict"
    }
  }
}
At least one of customer.address or customer.ip must be provided. If both are given, the address is used first with IP as a fallback.

​
Resolution Modes

ModeBehavior
strict (default)Error if IP cannot resolve to sufficient detail for tax calculation
zeroReturn zero-rate response if resolution is insufficient
approximateAttempts to resolve the IP to an address using heuristics
best_effortTry approximate first, fall back to zero rates
Numeral strongly recommends using strict mode to stay as compliant as possible.

​
New Response Fields

FieldDescription
location_source"address" or "ip" — which input was used
resolution_precisionSTREET, POSTAL_PLUS, POSTAL, PROVINCE, COUNTRY, or APPROXIMATED
address_usedThe resolved address used for tax calculation

​
IP Resolution Errors

Error TypeHTTP CodeDescription
INVALID_IP_FORMAT400ip.value is not a valid IPv4 or IPv6 address
IP_RESOLUTION_FAILED422IP could not be resolved to any country
IP_RESOLUTION_INSUFFICIENT_US422IP resolved to a US state but no postal code could be determined
IP_RESOLUTION_INSUFFICIENT_CA422IP resolved to Canada but no province could be determined

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>
required

API version to use.

Available options:
2026-03-01,
2026-01-01,
2025-05-12,
2024-09-01

Body

application/json
​
customer
object
required

Customer details. At least one of address or ip must be provided.

​
origin_address
object
required

Required from API version 2025-05-12+. The address that a product is shipped from.

​
order_details
object
required
​
metadata
object

You can store arbitrary keys and values in the metadata. Any valid JSON object whose values are less than 255 characters long is accepted.

Response

Calculate response

​
id
string

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

Example:

"calc_123456789"

​
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.

​
automatic_tax
enum<string>

The automatic tax setting for this calculation.

Available options:
auto,
disabled
Example:

"auto"

​
line_items
object[]
​
tax_included_in_amount
boolean
Example:

false

​
total_tax_amount
number

Total tax to charge on this calculation.

Example:

14

​
total_amount_excluding_tax
number

Total sale charge, excluding tax.

Example:

200

​
total_amount_including_tax
number

Total sale charge plus tax. What you should charge your customer.

Example:

214

​
expires_at
number

Epoch datetime representing the date and time the tax rates are valid until.

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.

​
metadata
object

You can store arbitrary keys and values in the metadata. Any valid JSON object whose values are less than 255 characters long is accepted.

​
location_source
enum<string>

Which input was used for tax determination.

Available options:
address,
ip
Example:

"address"

​
resolution_precision
enum<string>

The precision level of the resolved location.

Available options:
STREET,
POSTAL_PLUS,
POSTAL,
PROVINCE,
COUNTRY,
APPROXIMATED
Example:

"POSTAL"