@agenttax/ampersend

Tax compliance layer for Ampersend x402 agent payments. Wraps any X402Treasurer to automatically calculate US sales tax on every settled transaction.

Zero dependencies beyond the Ampersend SDK you already have.

Install

npm install @agenttax/ampersend

Or copy index.js directly -- it's a single file with no dependencies.

Quick Start

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 with tax compliance -- 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 automatically on every accepted payment.

What It Does

Every time an x402 payment settles through your Ampersend Treasurer:

1. The payment goes through normally (your Treasurer logic is unchanged)
2. On status: "accepted", AgentTax calculates the applicable sales tax
3. The tax result (amount, rate, jurisdiction, statute citation) is logged
4. Your onTaxCalculated callback fires if provided

Tax calculation never blocks or delays payments -- it runs async after settlement.

Get Tax Summary

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

console.log(summary);
// {
//   transactions: 47,
//   totalAmount: 125.50,
//   totalTax: 6.28,
//   effectiveRate: 0.05,
//   byJurisdiction: { Texas: 4.50, California: 0, "New York": 1.78 }
// }

Per-Transaction Tax Details

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 section151.351 -- 20% statutory exemption
  },
});

Dynamic State Resolution

If your agents transact across multiple states, provide a resolveState function:

const taxTreasurer = withTaxCompliance(treasurer, {
  apiKey: "atx_live_...",
  defaultBuyerState: "CA",           // Fallback
  transactionType: "saas",
  resolveState: (context, authorization) => {
    // Determine state from payment context metadata
    return context?.metadata?.buyerState || "CA";
  },
});

Standalone Calculator

Don't use Ampersend's Treasurer pattern? Use the standalone calculator:

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 calculation
for (const payment of ampersendPaymentHistory) {
  await tax.calculate({
    amount: payment.amountUsd,
    buyerState: payment.buyerState,
    counterpartyId: payment.sellerId,
  });
}

console.log(tax.getTaxSummary());

How Tax Works for x402 Payments

When your agent pays for compute/API/storage via x402:

• 45 states + DC levy sales tax on digital services
• Each state classifies AI agent transactions differently ("data processing" in TX, "prewritten software" in NY, "digital automated service" in WA)
• Texas applies an 80% taxable rule (section151.351) -- $1.00 payment = $0.05 tax, not $0.0625
• Connecticut has a separate 1% rate for data processing vs 6.35% for info services
• Iowa exempts B2B digital transactions entirely
• The rate depends on what the agent does, where the buyer is, and who is buying

AgentTax resolves all of this per-transaction. Every response includes the jurisdiction, statute citation, and confidence score.

API Key

Get a free API key at agenttax.io -- 100 calls/month, no credit card.

Paid plans: Starter $25/mo (10K calls), Growth $99/mo (100K), Pro $199/mo (1M).

Try it without signing up: agenttax.io/playground

Links

• AgentTax -- The tax engine for AI agent commerce
• AgentTax API Docs
• Python SDK -- pip install agenttax
• Ampersend -- The control layer for the agent economy
• Ampersend SDK
• x402 Protocol

License

MIT