Sales Tax Calculator API Reference

Overview

Sales Tax Calculator works by looking up current tax rates for the specified location and applying them to your purchase amount. For ZIP code lookups, you get a detailed breakdown of all applicable tax rates including state, county, city, and special district taxes.

Endpoint

One host, one path per API. The block below shows this call in four languages; every one of them is the same HTTP request. Making requests covers the timeouts, retries and parameter rules that apply to all of them. The SDKs wrap the same call in a typed client.

GEThttps://api.apiverve.com/v1/salestaxcalculator

curl "https://api.apiverve.com/v1/salestaxcalculator?amount=100&zip=90210&state=CA" \
  -H "x-api-key: your_api_key_here"

const res = await fetch('https://api.apiverve.com/v1/salestaxcalculator?amount=100&zip=90210&state=CA', {
  headers: { 'x-api-key': 'your_api_key_here' },
});

if (!res.ok) throw new Error(`${res.status} ${await res.text()}`);

const { data } = await res.json();
console.log(data);

import requests

res = requests.get(
    "https://api.apiverve.com/v1/salestaxcalculator?amount=100&zip=90210&state=CA",
    headers={"x-api-key": "your_api_key_here"},
    timeout=15,
)
res.raise_for_status()

print(res.json()["data"])

package main

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

func main() {
	req, _ := http.NewRequest("GET", "https://api.apiverve.com/v1/salestaxcalculator?amount=100&zip=90210&state=CA", nil)
	req.Header.Set("x-api-key", "your_api_key_here")

	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()

	out, _ := io.ReadAll(res.Body)
	fmt.Println(string(out))
}

Replace your_api_key_here with the key from your dashboard. When the inputs arrive as a list rather than one at a time, batch requests run up to 200 of them through this same API in a single call.

Authentication

Send your key in the x-api-key header. That is the only auth step — there is no token exchange and no per-endpoint scope to configure. Authentication covers creating, rotating and revoking keys.

401 is the only auth verdict

A 401 means the key is missing, invalid or expired. A 403 means the key is valid but not permitted here — blocked by a key restriction or an IP allow-list. Running out of credits is a 429.

Parameters

Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them.

Parameter	Type	Description
`amount`Required	number	Purchase amount to calculate tax on range 0–∞
`zip`Required	string	Valid US 5-digit ZIP code length 5–5
`state`Optional	string	2-letter US state code (e.g., CA, NY, TX) length 2–2

Response

Every API returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape. Response format covers the envelope, the other output formats and how premium fields are withheld.

Sample response

{
  "status": "ok",
  "error": null,
  "data": {
    "amount": 100,
    "taxRate": 0.0975,
    "taxRatePercent": 9.75,
    "taxAmount": 9.75,
    "totalAmount": 109.75,
    "zip": "90210",
    "state": "CA",
    "region": "Beverly Hills",
    "breakdown": {
      "stateRate": 0.0725,
      "countyRate": 0.0025,
      "cityRate": 0.0125,
      "specialRate": 0.01
    }
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Field	Type	Example	Description
`amount`	number	`100`	The original purchase amount before tax
`taxRate`	number	`0.0975`	Decimal tax rate applied to location
`taxRatePercent`	number	`9.75`	Tax rate expressed as percentage
`taxAmount`	number	`9.75`	Calculated tax amount for purchase
`totalAmount`	number	`109.75`	Total amount including tax
`zip`	string	`"90210"`	ZIP code used for tax calculation
`state`	string	`"CA"`	State code used for tax lookup
`region`Premium	string	`"Beverly Hills"`	City or region name for location
`breakdown`Premium	object	`{...}`	Detailed tax rate breakdown by category
`stateRate`Premium	number	`0.0725`	State-level tax rate component
`countyRate`Premium	number	`0.0025`	County-level tax rate component
`cityRate`Premium	number	`0.0125`	City-level tax rate component
`specialRate`Premium	number	`0.01`	Special district tax rate component

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change. Error handling covers the full status list and which of them are worth retrying.

Status	Meaning	What to do
`400`	Input was rejected	Read `error`; it names the parameter.
`401`	Key missing or invalid	Check the header name and the key value.
`403`	Key valid, but not permitted	A key restriction or IP allow-list; see key scoping.
`429`	Rate limited, or out of credits	Read `error` to tell them apart; see rate limits.

Use cases

E-commerce Checkout: Calculate accurate sales tax at checkout based on customer shipping address for tax-compliant transactions
Point of Sale Systems: Integrate real-time tax calculations into POS systems for accurate receipt generation
Invoice Generation: Automatically calculate and add sales tax to invoices based on customer location
Price Quoting: Generate accurate price quotes that include applicable sales tax for any US location

Other ways to use Sales Tax Calculator

Set up Sales Tax Calculator on APIVerve, or reach the same source a different way. Your APIVerve account and credits work on all of them — one key, one balance.

Give it to an AI agentConnect over MCP and your agent calls it as a native tool — Claude, Cursor, ChatGPT.VerveKit →Reference →

Use it in Google Sheets or ExcelA =VERVE() formula fills a column — no script, no export, recalculates in place.VerveSheets →Reference →

Ground an agent on itA cited, machine-checkable fact your model can't produce on its own.VerveContext →Reference →

Sales Tax Calculator