OpenChainGraph Suite · ART-338 · US Payroll Compliance

Federal Withholding Calculator

Federal income tax withholding via the IRS Publication 15-T percentage method, Worksheet 1A, for a 2020-or-later Form W-4. Select the tax year: the 2025 and 2026 editions are both supported. Supports single/MFS, married filing jointly, and head of household, plus Step 3 dependents credit and Step 4(a)/(b)/(c) adjustments. Feeds ART-339 Gross-to-Net Payroll Calculator.

IRS Pub 15-T (2025) Worksheet 1A Percentage Method Federal Only

🔒 All inputs are processed locally in your browser. No data is transmitted. Do not enter real personal data — use synthetic or anonymised inputs only.

⚠ Federal withholding only. Not tax advice. State and local withholding are out of scope for this tool. The Form W-4 Step 2 multiple-jobs checkbox withholding table is not implemented in v1 — results assume the box is not checked.

Pay & Filing Status

Gross wages this pay period ($)

Pay frequency

Tax year

Selects the Pub 15-T edition. 2026 is Section 1; 2025 is Section 4.

Filing status (Form W-4 Step 1(c))

Form W-4 Steps 3 & 4 (optional)

Step 3: dependents credit ($/yr)

Step 4(a): other income ($/yr)

Step 4(b): deductions ($/yr)

Step 4(c): extra withholding ($/period)

Worksheet 1A Detail

Execution Hash (SHA-256)

Ask your agent

Copy this paragraph into Claude, OpenClaw, or any MCP-aware agent to run this exact tool, with this sample, and verify the artifact.

Run the AINumbers MCP tool `compute_federal_withholding`. Task: Federal income tax withholding via the IRS Publication 15-T percentage method, Worksheet 1A, for a 2020-or-later Form W-4.
Call it with arguments: {"policy_parameters":{"tax_year":"2026","gross_wages_per_period":2000,"pay_frequency":"biweekly","filing_status":"single_or_mfs"}}
Verify before trusting: call `verify_execution_hash` on mcp.ainumbers.co (https://mcp.ainumbers.co/mcp) with the parameter `claimed_hash` set to the returned `execution_hash`, passing the full artifact the run returned (the object containing `policy_parameters` + `output_payload` + `execution_hash`; equivalently `policy_parameters` + `output_payload` with `claimed_hash`), not the bare hash string.
Return the ledger link https://ledger.ainumbers.co/ so a human can re-verify without contacting us.
PII rule: All inputs are processed locally in your browser. No data is transmitted. Do not enter real personal data — use synthetic or anonymised inputs only.
Open the tool with the sample prefilled: https://ainumbers.co/chaingraph/art-338-compute-federal-withholding.html#p=v1.H4sIAAAAAAAA_wFsAJP_eyJ0YXhfeWVhciI6IjIwMjYiLCJncm9zc193YWdlc19wZXJfcGVyaW9kIjoyMDAwLCJwYXlfZnJlcXVlbmN5IjoiYml3ZWVrbHkiLCJmaWxpbmdfc3RhdHVzIjoic2luZ2xlX29yX21mcyJ9rOd-72wAAAA