AgentTax

Tax compliance tools for AI agent transactions. Use when the user or agent needs to:

• Calculate sales tax or use tax on a transaction
• Log trades for capital gains tracking
• Check tax rates by state
• Configure economic nexus states
• Export 1099-DA data

API docs: https://agenttax.io/api/v1/agents

Authentication

All requests use the header: X-API-Key: $AGENTTAX_API_KEY

Get a free API key (100 calls/month):

curl -s -X POST https://agenttax.io/api/v1/auth/signup \
  -H "Content-Type: application/json" \
  -d '{"email": "you@example.com", "password": "securepass", "agent_name": "my-agent"}'

Save the api_key.key from the response — it is only shown once.

Calculate Sales/Use Tax

Use when an AI agent buys or sells services, compute, API access, SaaS, or digital goods.

curl -s -X POST https://agenttax.io/api/v1/calculate \
  -H "X-API-Key: $AGENTTAX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "role": "ROLE",
    "amount": AMOUNT,
    "buyer_state": "STATE",
    "buyer_zip": "ZIP",
    "transaction_type": "TYPE",
    "work_type": "WORK_TYPE",
    "counterparty_id": "COUNTERPARTY",
    "is_b2b": IS_B2B
  }'

Required fields:

• role: "buyer" or "seller"
• amount: transaction amount in USD
• buyer_state: 2-letter US state code
• transaction_type: one of compute, api_access, data_purchase, saas, ai_labor, storage, digital_good, consulting, data_processing, cloud_infrastructure, ai_model_access, marketplace_fee, subscription, license, service
• counterparty_id: identifier for the other party

Optional fields:

• buyer_zip: 5-digit zip for local rate lookup (recommended — adds city/county tax)
• work_type: compute, research, content, consulting, trading (drives per-state classification)
• is_b2b: true/false (affects rates in MD, IA)
• seller_remitting: true/false (whether seller is collecting tax)

Response includes: total_tax, combined_rate, jurisdiction, audit_trail, confidence, advisories.

Sellers: you must configure nexus first (see below) or all calculations return $0.

Log Trades (Capital Gains)

Use when an agent buys or sells assets (compute tokens, crypto, etc.).

# Buy
curl -s -X POST https://agenttax.io/api/v1/trades \
  -H "X-API-Key: $AGENTTAX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "asset_symbol": "SYMBOL",
    "trade_type": "buy",
    "quantity": QTY,
    "price_per_unit": PRICE
  }'

# Sell (returns realized gain/loss)
curl -s -X POST https://agenttax.io/api/v1/trades \
  -H "X-API-Key: $AGENTTAX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "asset_symbol": "SYMBOL",
    "trade_type": "sell",
    "quantity": QTY,
    "price_per_unit": PRICE,
    "accounting_method": "fifo",
    "resident_state": "STATE"
  }'

Cost basis methods: fifo (default), lifo, specific_id.

Get Tax Rates

# All 51 jurisdictions
curl -s https://agenttax.io/api/v1/rates

# Single state with explanation
curl -s "https://agenttax.io/api/v1/rates?state=TX&explain=true"

Configure Nexus (Sellers Only)

Sellers must set nexus states to get non-zero tax results.

curl -s -X POST https://agenttax.io/api/v1/nexus \
  -H "X-API-Key: $AGENTTAX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "nexus": {
      "TX": { "hasNexus": true, "reason": "Economic nexus" },
      "NY": { "hasNexus": true, "reason": "Physical presence" }
    }
  }'

Health Check

curl -s https://agenttax.io/api/v1/health

Error Handling

All errors return { "success": false, "error": "message", "agent_guide": "https://agenttax.io/api/v1/agents" }.

• 400: Bad request — check error and errors fields
• 401: Invalid or missing API key
• 429: Rate limited (free tier: 100 calls/month)