One line. Estimated US sales tax liability.

Wrap your Ampersend X402Treasurer with automatic US sales tax calculation across all 50 states. Runs async — never touches your payment flow. Every settled transaction gets a tax calculation and audit trail.

How it works

Quick start

Wrap your existing Treasurer. Everything else stays the same.

import { createAmpersendTreasurer } from "ampersend-sdk";
import { withTaxCompliance } from "@agenttax/ampersend";

// Your existing Ampersend setup
const treasurer = createAmpersendTreasurer({
  wallet: myWallet,
  apiKey: process.env.AMPERSEND_SESSION_KEY,
});

// Wrap it — one line
const taxTreasurer = withTaxCompliance(treasurer, {
  apiKey: "atx_live_...",          // Free at agenttax.io — 100 calls/mo
  defaultBuyerState: "TX",         // Buyer's US state
  transactionType: "compute",      // compute, saas, api_access, consulting, etc.
});

// Use taxTreasurer exactly like your original treasurer.
// Tax is calculated async on every accepted payment — never blocks.

Get tax summary

Aggregate all tax calculations for reporting.

// After some transactions...
const summary = taxTreasurer.getTaxSummary();

console.log(summary);
// {
//   transactions: 47,
//   totalAmount: 125.50,
//   totalTax: 6.28,
//   effectiveRate: 0.05,
//   byState: { TX: 4.50, CA: 0, NY: 1.78 }
// }

Per-transaction callback

Get notified on every tax calculation with full jurisdiction details and statute citations.

const taxTreasurer = withTaxCompliance(treasurer, {
  apiKey: "atx_live_...",
  defaultBuyerState: "TX",
  transactionType: "compute",
  onTaxCalculated: (entry) => {
    console.log(`Payment ${entry.authorizationId}: ${entry.amount}`);
    console.log(`  Tax: ${entry.tax.total_tax} (${entry.tax.sales_tax?.jurisdiction})`);
    console.log(`  Rate: ${(entry.tax.sales_tax?.rate * 100).toFixed(2)}%`);
    console.log(`  Note: ${entry.tax.sales_tax?.note}`);
    // → Payment abc123: $5.00
    // →   Tax: $0.25 (Texas)
    // →   Rate: 6.25%
    // →   Note: TX Tax Code §151.351 — 20% statutory exemption
  },
});

Standalone calculator

Not using X402Treasurer? Use the standalone calculator for batch or retroactive tax on existing payments.

import { createTaxCalculator } from "@agenttax/ampersend";

const tax = createTaxCalculator({
  apiKey: "atx_live_...",
  defaultBuyerState: "NY",
  transactionType: "api_access",
});

// Calculate tax for any transaction
const result = await tax.calculate({ amount: 100.00 });
console.log(result.total_tax);  // 4.00 (NY 4% state rate)

// Batch — retroactive calculation on existing payments
for (const payment of ampersendPaymentHistory) {
  await tax.calculate({
    amount: payment.amountUsd,
    buyerState: payment.buyerState,
    counterpartyId: payment.sellerId,
  });
}

console.log(tax.getTaxSummary());

Direct REST (no SDK)

Prefer zero dependencies? Call the API directly.

// Direct REST — no SDK needed
const response = await fetch('https://agenttax.io/api/v1/calculate', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'X-API-Key': process.env.AGENTTAX_API_KEY,
  },
  body: JSON.stringify({
    role: 'seller',
    amount: 1250.00,
    buyer_state: 'WA',
    transaction_type: 'saas',
    counterparty_id: 'amp_buyer_77a3f',
    is_b2b: false,
  }),
});

const tax = await response.json();
// { taxable: true, total_tax: 87.50, combined_rate: 0.07, ... }

Why Ampersend sellers need this

Other integrations