Create Customers

Create a new customer

POST /tax/customers

cURL

cURL

curl --request POST \
  --url https://api.numeralhq.com/tax/customers \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "email": "[e-mail]",
  "name": "Customer Name",
  "is_tax_exempt": true,
  "reference_customer_id": "20506"
}
'

import requests

url = "https://api.numeralhq.com/tax/customers"

payload = {
    "email": "[e-mail]",
    "name": "Customer Name",
    "is_tax_exempt": True,
    "reference_customer_id": "20506"
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    email: '[e-mail]',
    name: 'Customer Name',
    is_tax_exempt: true,
    reference_customer_id: '20506'
  })
};

fetch('https://api.numeralhq.com/tax/customers', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.numeralhq.com/tax/customers",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'email' => '[e-mail]',
    'name' => 'Customer Name',
    'is_tax_exempt' => true,
    'reference_customer_id' => '20506'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.numeralhq.com/tax/customers"

	payload := strings.NewReader("{\n  \"email\": \"[e-mail]\",\n  \"name\": \"Customer Name\",\n  \"is_tax_exempt\": true,\n  \"reference_customer_id\": \"20506\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.numeralhq.com/tax/customers")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"email\": \"[e-mail]\",\n  \"name\": \"Customer Name\",\n  \"is_tax_exempt\": true,\n  \"reference_customer_id\": \"20506\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.numeralhq.com/tax/customers")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"email\": \"[e-mail]\",\n  \"name\": \"Customer Name\",\n  \"is_tax_exempt\": true,\n  \"reference_customer_id\": \"20506\"\n}"

response = http.request(request)
puts response.read_body

200

{
  "id": "cus_123456789",
  "object": "tax.customer",
  "reference_customer_id": "20506",
  "name": "Customer Name",
  "email": "[e-mail]",
  "is_tax_exempt": true
}

{
  "error": {
    "error_code": "missing_field",
    "error_message": "Field is required",
    "error_meta": {
      "field": "path.to.fieldname",
      "expected": "string",
      "received": "undefined"
    }
  }
}

Customer Endpoint (2026-03-01)

Create a new customer, and optionally mark them as tax exempt.

Remember to include the X-API-Version: 2026-03-01 header in your request to use this API version.

Important: If you provide a customer.id in calculations, it must exist (created via POST /tax/customers first)

Authorizations

Authorization · string · header · required

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

Body

application/json

email · string · required

The customer's email

Example:

"[e-mail]"

name · string

The customer's name

Example:

"Customer Name"

is_tax_exempt · boolean

If true, all POST /tax/calculations sold to this customer will return $0 in tax owed. The default value is false.

Example:

true

reference_customer_id · string

The ID of the customer in your system

Example:

"20506"

Response

200

application/json

Customer creation response

id · string

The ID of the customer

Example:

"cus_123456789"

object · string

The type of object: tax.customer

Example:

"tax.customer"

reference_customer_id · string

The ID of the customer in your system

Example:

"20506"

name · string

The name of the created customer

Example:

"Customer Name"

email · string

The email of the created customer

Example:

"[e-mail]"

is_tax_exempt · boolean

If true, all POST /tax/calculations sold to this customer will return $0 in tax owed. The default value is false.

Example:

true