Federal Withholding Calculator (Percentage Method)

Federal income tax withholding via the IRS Publication 15-T percentage method, Worksheet 1A, for a 2020-or-later Form W-4. tax_year is a required input and selects the edition: the 2026 Section 1 and 2025 Section 4 STANDARD Withholding Rate Schedules are both carried, and an absent or unsupported year fails closed with error unsupported_or_missing_tax_year rather than defaulting to an edition the caller never chose. Supports single/MFS, married filing jointly, and head of household, plus Step 3 dependents credit, Step 4(a) other income, Step 4(b) deductions, and Step 4(c) extra withholding. STANDARD Withholding Rate Schedules only; the Form W-4 Step 2 multiple-jobs checkbox table is out of scope. Federal only, not tax advice, state withholding out of scope. Feeds art-339-compute-gross-to-net as its federal_withholding_per_period input, which must be called with the same tax_year. Not compute_gross_to_net itself, which computes FICA and net pay.

Tool URL: https://ainumbers.co/chaingraph/art-338-compute-federal-withholding.html