1. Establish gross wages
Salary input is normalized to annual gross wages. Hourly input is annualized from the regular hourly rate, weekly hours and 52 weeks; weekly overtime is calculated separately with the selected multiplier. Annual bonus input is then handled using the chosen supported method.
The engine converts annual values to the selected number of payroll periods only after building the annual wage picture. This makes weekly, biweekly, semimonthly, monthly and annual views consistent.
2. Apply supported pre-tax deductions
Supported retirement and health-related amounts are subtracted according to the engine’s documented wage-base assumptions. A deduction can affect federal income-tax wages differently from Social Security and Medicare wages, so the result should be compared with the employer plan description.
3. Calculate federal withholding
The calculator uses the 2026 IRS Publication 15-T automated percentage method for a 2020-or-later Form W-4. Filing status, Step 2(c), Step 3 credits, Step 4(a) other income, Step 4(b) deductions and Step 4(c) additional withholding are supported.
Federal withholding is a payroll prepayment estimate. It is not a calculation of final annual tax liability, refund or amount due.
4. Calculate employee payroll taxes
Employee Social Security withholding is calculated against the supported wage base and annual limit. Medicare and Additional Medicare are calculated separately under their applicable wage rules. Florida individual income tax is then shown explicitly as $0 rather than being omitted.
5. Subtract deductions and produce net pay
After federal withholding and employee payroll taxes, the engine subtracts supported pre-tax and post-tax payroll deductions to produce estimated net pay. It also reports annual net and equivalent amounts for common frequencies.
Rounding and comparison with payroll
Internal calculations use decimal dollar values and displayed paycheck amounts are rounded to cents. Employer systems may round at different steps or calculate against actual pay dates and year-to-date wage history, producing small differences.
Verification approach
Golden tests cover official withholding-table transitions, filing statuses, FICA limits, Additional Medicare, invalid values, hourly overtime and bonus paths. Tax-year constants are isolated from page copy so a future year requires deliberate review and activation.
Changes to presentation components should not change engine output. When the interface changes, identical input fixtures are rerun to confirm identical results.
Known limitations
The calculator does not handle pre-2020 W-4 allowances, nonresident-alien adjustments, tips, clergy rules, household employment, stock compensation, local taxes outside Florida, garnishment law or self-employment tax. It does not determine benefit eligibility, overtime entitlement or final tax liability.