---
title: "Federal income tax on ordinary income for 2026: AGI from gross minus above-the-line adjustments, standard or itemized deduction, the 2026 brackets, and a flat nonrefundable credit amount. Distinct from /v1/paycheck (which nets FICA + state per pay period)."
method: POST
path: "/v1/tax/federal-income"
tags: ["Payroll & tax"]
---

# Federal income tax on ordinary income for 2026: AGI from gross minus above-the-line adjustments, standard or itemized deduction, the 2026 brackets, and a flat nonrefundable credit amount. Distinct from /v1/paycheck (which nets FICA + state per pay period).

`POST /v1/tax/federal-income`

## Request

- Base URL: `` (relative, and it does not resolve against the document’s source URL)
- URL: `/v1/tax/federal-income`
- Auth: none declared

Federal income tax on ordinary income for 2026: AGI from gross minus above-the-line adjustments, standard or itemized deduction, the 2026 brackets, and a flat nonrefundable credit amount. Distinct from /v1/paycheck (which nets FICA + state per pay period).

Payment: x402 ($0.05 USDC on eip155:8453). Call unpaid to receive an HTTP 402 with requirements, then retry with the PAYMENT-SIGNATURE header. Method: AGI = grossIncome - adjustments; taxable = max(AGI - deduction, 0); tax = marginal 2026 brackets (MFJ doubles single thresholds); totalTax = max(tax - credits, 0)

## Request body

- object
  - `grossIncome` number, required
  - `filingStatus` 'single' | 'mfj'
  - `adjustments` number
  - `deductionType` 'standard' | 'itemized'
  - `itemizedDeductions` number
  - `credits` number

## Response `200`

Verified result + provenance (formula, sources, reproducible SHA-256 hash).

## Other responses

- `400`: Invalid input (no charge) — body echoes the JSON Schema.
- `402`: Payment required — PAYMENT-REQUIRED header carries the x402 accepts[] quote.

---

[API](https://skmtc.dev/x402toll/apis/tollbooth-verified-calculators-for-ai-agents.md) · [All operations](https://skmtc.dev/x402toll/apis/tollbooth-verified-calculators-for-ai-agents/llms.txt) · [OpenAPI document](https://skmtc.dev/x402toll/apis/tollbooth-verified-calculators-for-ai-agents/revisions/60cb70a3e1a5?raw)