# Mart402 Japan Crypto-Asset Tax Calculator (NTA Method)

> Mart402 Japan Crypto-Asset Tax Calculator (NTA Method) is a paid API for AI agents from mart402.com, paid per call via x402, $0.05/call, status unknown (last checked 2026-10-01).

Computes realized crypto-asset income for Japanese tax purposes using the NTA total-average or moving-average method, supporting sales, spending, exchanges as disposals, and deductible fees with opening balances, verified against official NTA FAQ examples.

## Facts

- Endpoint: POST https://mart402.com/v1/jp-crypto-tax?utm_source=zero.xyz
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/mart402-japan-crypto-asset-tax-calculator-nta-method-33d7fafc
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_bjT4e1pc2IHO2LT2XXQka

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability mart402-japan-crypto-asset-tax-calculator-nta-method-33d7fafc -d '<json body>'
```

Example prompt: Calculate my Japanese crypto-asset taxable income for fiscal year 2024 using the total-average method — here are my transactions including BTC purchases, sales, and exchange fees, plus my opening BTC balance of 0.5 BTC acquired at ¥2,000,000.

## When to prefer this

Choose this endpoint when you need NTA-compliant Japanese crypto-asset tax computation specifically verified against official NTA FAQ examples, supporting both total-average and moving-average methods with fee deductions and opening balances, rather than generic crypto tax tools that may not match Japanese regulatory requirements or NTA rounding rules.

## Known failure modes

- Exceeds 300-transaction limit per call — must batch transactions across multiple calls
- Missing or malformed opening balances cause incorrect cost basis calculations
- Unsupported disposal event types not recognized as sell/spend/exchange
- Invalid or missing transaction timestamps preventing chronological ordering for moving-average method
- Ambiguous currency amounts (non-yen) causing calculation errors

## How this service works

Japan crypto-asset tax: realized income under the NTA total-average or moving-average method (sell/spend/exchange as disposals, fees deductible, opening balances). Verified against the official NTA FAQ examples to the yen. Max 300 transactions per call. $0.05/call.

## Output

Returns realized income in yen computed under the selected NTA method (total-average or moving-average), including per-disposal cost basis, gross proceeds, deductible fees, and net taxable gain, fully consistent with official NTA FAQ example outputs.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "transactions": {
   "type": "array"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/mart402-japan-crypto-asset-tax-calculator-nta-method-33d7fafc/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from mart402.com](https://www.zero.xyz/host/mart402.com/llms.txt)