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The calculation object contains tax rate information. A calculation also includes a calculation_id that you’ll use to record a transaction for filing.

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When to create Calculations

Calculations should be used any time you need to calculate sales tax before charging a customer for a transaction. Most e-commerce clients will submit a POST to /tax/calculations during their checkout flow after the end customer has submitted their address, but before collecting payment. core flow

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How to 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: 2024-09-01' \
  --data '{
  "customer": {
    "address": {
      "address_line_1": "3990 N County Rd 300 E",
      "address_city": "Danville",
      "address_province": "IN",
      "address_postal_code": "46122",
      "address_country": "US",
      "address_type": "shipping"
    }
  },
  "order_details": {
    "customer_currency_code": "USD",
    "tax_included_in_amount": false,
    "line_items": [
      {
        "reference_line_item_id": "line_123456789",
        "product_category": "GENERAL_MERCHANDISE",
        "amount": 200,
        "quantity": 2
      }
    ]
  }
}'

{
  "calculation_id": "calc_17364047950082c1fd8f0-f763-40f8-8c02-e8fc9ded0944",
  "object": "tax.calculation",
  "line_items": [
    {
      "line_item_id": "line_987654321",
      "reference_product_id": "temp-a4a427d4-42fc-47f1-9092-c74f935438a3",
      "reference_product_name": "temp-a4a427d4-42fc-47f1-9092-c74f935438a3",
      "product_tax_code": "GENERAL_MERCHANDISE",
      "tax_included_in_amount": true,
      "tax_jurisdictions": [
        {
          "tax_rate": 0.07,
          "rate_type": "REDUCED_RATE",
          "jurisdiction_name": "State"
        }
      ],
      "tax_amount": 14,
      "amount_excluding_tax": 200,
      "amount_including_tax": 214
    }
  ],
  "total_tax_amount": 14,
  "total_amount_excluding_tax": 200,
  "expires_at": 1714787673,
  "testmode": "false"
}
We return both the aggregate tax information as well as a detailed breakdown for each line item. Many users will just use the total_tax_amount to identify what to charge a user, but you will always have the details as you need them.

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Request Parameters

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Customer Object

{
  "customer": {
    "id": "cus_123456789", // Optional customer ID
    "address": {
      "address_line_1": "3990 N County Rd 300 E",
      "address_line_2": "Unit 2", // Optional
      "address_city": "Danville",
      "address_province": "IN",
      "address_postal_code": "46122",
      "address_country": "US",
      "address_type": "shipping" // "shipping" or "billing"
    }
  }
}
The customer object requires an address for tax calculation purposes.

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Order Details

{
  "order_details": {
    "customer_currency_code": "USD", // Supports EUR, RON, PLN, DKK, HUF, CZK, BGN, SEK, USD, CAD
    "tax_included_in_amount": false,
    "line_items": [
      {
        "reference_line_item_id": "line_123456789", // Optional
        "reference_product_id": "p-1233543", // Required if no product_category
        "product_category": "GENERAL_MERCHANDISE", // Required if no reference_product_id
        "fallback_product_category": "GENERAL_MERCHANDISE", // Optional - used if reference_product_id is not found in Numeral
        "amount": 200, // In currency's smallest unit (e.g., cents for USD, whole units for JPY)
        "quantity": 2
      }
    ]
  }
}
  • fallback_product_category (string, optional): If you pass a reference_product_id that does not exist in Numeral, the calculation falls back to this product category instead of returning a 400. Must be a valid product category from the Numeral taxonomy. If the reference_product_id is found, its stored category takes precedence.

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Further documentation

The full documentation for creating calculations is on this page.