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 (1,500 calls/month):

curl -s -X POST https://agenttax.io/api/v1/auth/signup \
  -H "Content-Type: application/json" \
  -d '{"email": "[email protected]", "password": "securepass", "agent_name": "my-agent", "agent_work_type": "compute"}'

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, payment_processing_fee, web_hosting, software_maintenance, it_support
• 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, information_service, content, consulting, trading, payment_processing, web_hosting, software_maintenance, it_support, custom_software (drives per-state classification). Send it only when you know it: it is a declared fact, not a guess. consulting is an exempt professional service in Arizona, and the consulting / trading exemptions apply only to a declared work type. Send it for an exact answer
• is_b2b: true/false (affects rates in MD, IA)
• seller_remitting: true/false (whether seller is collecting tax)
• Classification facts, each for one classification type; absent = the conservative answer:
• payment_provider_type (with payment_processing_fee): bank, licensed_money_transmitter, card_network, processor_routing_to_bank_or_network, other
• it_support_scope (with it_support): help_desk_advice, remote_repair_or_config, software_installation, monitoring, security_monitoring, managed_bundle (the default)
• includes_prewritten_software_access (with web_hosting): true when the plan includes vendor software beyond a control panel or file manager
• custom_software_attestation (required with work_type custom_software, or the sale is answered as SaaS): written_for_buyer, not_offered_to_others, deliverable (source_code | compiled_artifact | hosted), is_modification_of_prewritten; optional separately_stated_charge, all_rights_transferred, delivery, il_requirements_analysis_and_adaptation, il_assembled_modules_50pct
• maintenance_contract (with software_maintenance), all optional: mandatory, includes_upgrades, includes_support, separately_itemized, itemized_amounts {updates, support}, update_delivery, support_kind (help_desk_only | includes_fixes), seller_sold_software, business_use. Unknown keys in either object are rejected
• intent: "estimate" or "record". "estimate" quotes before a wallet signs: nothing is saved to history or nexus revenue, but it counts toward your monthly calls. Keyed calls default to "record". Needs the AgentTax API release that accepts intent; until then omit it

Response includes: total_tax, combined_rate, jurisdiction, audit_trail, confidence, advisories, and (from the same API release) resolution. resolution.location, resolution.nexus and resolution.taxability each carry status (resolved | partial | unknown), basis and detail. total_tax is always returned; to treat "unknown" as "do not charge", branch on resolution.*.status.

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: 1,500 calls/month)