---
title: "US sales tax — add or remove tax using the verified 2026 STATE base rate for any state + DC, plus an optional local rate. Flags gross-receipts states (HI/NM) and local-only states (AK)."
method: POST
path: "/v1/commerce/sales-tax"
tags: ["Commerce"]
---

# US sales tax — add or remove tax using the verified 2026 STATE base rate for any state + DC, plus an optional local rate. Flags gross-receipts states (HI/NM) and local-only states (AK).

`POST /v1/commerce/sales-tax`

## Request

- Base URL: `` (relative, and it does not resolve against the document’s source URL)
- URL: `/v1/commerce/sales-tax`
- Auth: none declared

US sales tax — add or remove tax using the verified 2026 STATE base rate for any state + DC, plus an optional local rate. Flags gross-receipts states (HI/NM) and local-only states (AK).

Payment: x402 ($0.05 USDC on eip155:8453). Call unpaid to receive an HTTP 402 with requirements, then retry with the PAYMENT-SIGNATURE header. Method: combined = stateRate + localRate; add: tax = amount*rate/100; remove: base = amount/(1+rate/100), tax = amount-base

## Request body

- object
  - `state` string, required: 2-letter US state/DC code
  - `amount` number, required
  - `mode` 'add' | 'remove'
  - `localRatePct` number

## Response `200`

Verified result + provenance (formula, sources, reproducible SHA-256 hash).

## Other responses

- `400`: Invalid input (no charge) — body echoes the JSON Schema.
- `402`: Payment required — PAYMENT-REQUIRED header carries the x402 accepts[] quote.

---

[API](https://skmtc.dev/x402toll/apis/tollbooth-verified-calculators-for-ai-agents.md) · [All operations](https://skmtc.dev/x402toll/apis/tollbooth-verified-calculators-for-ai-agents/llms.txt) · [OpenAPI document](https://skmtc.dev/x402toll/apis/tollbooth-verified-calculators-for-ai-agents/revisions/60cb70a3e1a5?raw)