W-2 tax calculation API for 2026, pay-per-request via x402 on Base (USDC).
What it does
This endpoint at lowpaymentfee.com provides a W-2 tax calculation service for the 2026 tax year, accessible via HTTP POST with x402 micropayments. It is part of a broader platform offering dozens of pay-per-call APIs spanning data analytics, AI/ML inference, finance, crypto, and utility services — all settled on the Base network using USDC.
The specific endpoint `/api/v1/tax/w2/2026` costs $0.02 per request (20,000 base units of USDC with 6 decimals). Payment is handled inline via the x402 protocol: callers attach an `X-PAYMENT` header containing a signed payment proof, and the server processes the request without requiring API keys, accounts, or rate limits. The x402 challenge confirms the endpoint is live and accepting payments to address `0x1A2B...85F3` on Base.
Documentation is extremely sparse. The crawled docs, API, pricing, and README pages all returned only a "Connect wallet" prompt with no substantive content. There is no OpenAPI schema, no description of the request body format for W-2 tax calculations, and no sample responses. The endpoint's actual input fields (e.g., wages, withholdings, filing status) and output structure are unknown. Users will need to experiment or contact the provider to determine the expected payload.
Capabilities
Use cases
- —Calculating estimated 2026 federal taxes from W-2 wage and withholding data
- —Integrating tax estimation into payroll or HR software
- —Agent-driven tax planning workflows that need per-call tax computations
Fit
Best for
- —Developers needing on-demand W-2 tax calculations without subscription commitments
- —AI agents that can pay per request via x402 on Base
- —Applications requiring 2026 tax-year-specific calculations
Not for
- —Users who need detailed documentation or guaranteed schema stability before integrating
- —Tax scenarios beyond W-2 (e.g., 1099, K-1, business taxes) — no evidence those are supported at this endpoint
- —High-volume batch processing where $0.02/request adds up significantly
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/tax/w2/2026 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>" \
-d '{"wages": 75000, "federal_withheld": 12000, "filing_status": "single"}'Example
Request
{
"state": "CA",
"wages": 75000,
"filing_status": "single",
"federal_withheld": 12000
}Endpoint
Quality
The endpoint is confirmed live via a valid x402 402 challenge, and pricing is clear ($0.02/request in USDC on Base). However, there is no documentation, no OpenAPI schema, no request/response examples, and the request body format is entirely unknown. The example request JSON above is speculative. This is effectively a stub listing.
Warnings
- —No documentation available — docs, API, pricing, and README pages all return only a wallet-connect prompt with no content.
- —Request body schema for W-2 tax calculation is completely unknown; the example_request_json is speculative.
- —No response schema or sample response is available.
- —2026 tax year implies forward-looking tax rules that may not yet be finalized by the IRS.
Citations
- —Endpoint returns a valid x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/tax/w2/2026
- —Platform advertises $0.02 per request pricing with no API keys, no rate limits, and Base network settlementhttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/tax/w2/2026