Our calculation principles
NetPayKit aims to make planning estimates understandable and reproducible. We label the calculation year, separate gross pay from individual deductions, use documented federal sources, and state what is excluded. Calculator outputs are rounded for display, while intermediate calculations retain additional precision.
2026 paycheck and salary estimates
Gross pay is annualized from the selected payroll frequency. Federal income tax withholding is estimated using 2026 federal percentage method concepts and the Form W-4 inputs supported by the calculator. The annual estimate is converted back to the selected pay period.
Employee FICA is calculated separately. Social Security is generally 6.2% of covered wages up to the 2026 annual wage base of $184,500. Medicare is generally 1.45% of covered wages without a wage-base cap. Additional Medicare withholding is considered where the calculator supports wages above the employer withholding threshold.
2026 bonus withholding estimate
The bonus calculator supports separately identified supplemental wages under IRS Publication 15 (2026), section 7. The optional flat method applies 22% only after the user confirms that the employer paying this bonus withheld federal income tax from this employee's regular wages in 2026 or 2025. Confirm that fact with the paying employer or its payroll provider. The aggregate method estimates Publication 15-T withholding on regular wages plus the eligible bonus portion and subtracts the estimate for regular wages alone.
The aggregate estimate models one separately identified current bonus. It does not accept earlier supplemental payments or the tax already withheld from those payments in the same payroll period. Publication 15 requires payroll to aggregate and subtract those earlier same-period amounts, so this calculator should not be used as a substitute for that payroll record.
A $0 regular-wage reference is appropriate only when no concurrent, current-period, or preceding-period regular wages are available for the aggregate method. When those wages exist, they must be entered for a meaningful estimate.
Prior calendar-year supplemental wages determine how much of a new payment remains at or below $1 million. Under the calculator's excess-only model, only the portion above that cumulative threshold is withheld at the mandatory 37% rate. The calculator displays both sides of a threshold-crossing payment.
This is the excess-only approach. Treasury regulations also permit an employer to apply the mandatory 37% rate to the entire current supplemental payment that crosses the threshold; NetPayKit does not model that employer election.
Employee FICA is calculated independently on the full bonus using the entered prior Social Security and Medicare wages. The result is a withholding estimate, not the employee's final income tax.
2026 gross-up and net-to-gross estimate
The gross-up calculator uses the same 2026 regular-wage federal withholding and employee FICA functions as the paycheck calculator. It searches integer gross-pay cents for the first paycheck whose net result reaches the entered target. It then evaluates the immediately preceding gross cent and reports that lower net result as evidence that the returned gross is minimal.
Gross pay is treated as fully taxable for federal income tax, Social Security, and Medicare. The optional fixed deduction is explicitly post-tax: it is subtracted once after tax and never reduces either taxable wage base. Pre-tax benefits and employer-specific deduction classifications are outside this first release.
The search preserves the existing federal engine's exact-cent rounding and threshold behavior. When no gross cent produces the exact target, the first result above it is returned with the small excess shown. The calculator fails closed if the target cannot be reached inside its documented gross-pay limit.
Pay conversions
- Hourly to annual pay: hourly rate × weekly hours × weeks worked.
- Salary to hourly pay: annual salary ÷ (weekly hours × weeks worked).
- Common frequencies use 52 weekly, 26 biweekly, 24 semimonthly, and 12 monthly periods unless a calculator states otherwise.
Overtime estimates
The overtime calculator models one straightforward hourly workweek. The user supplies the non-overtime hours, overtime hours already determined under the applicable rule, hourly rate, and multiplier. It calculates non-overtime earnings at the entered rate and full overtime earnings at the entered rate multiplied by the selected multiplier. A 1.5 multiplier represents time-and-a-half.
The engine retains the entered rate, hours, and multiplier through each multiplication, then rounds regular earnings and overtime earnings separately to the nearest cent before adding them; an exact half-cent tie rounds up. The displayed audit trail shows the unrounded overtime rate when needed so its multiplication reconciles with the final cents.
The calculator does not identify overtime hours or determine legal entitlement. Under the general federal rule, each fixed 168-hour workweek stands alone and cannot be averaged with another week. The legal regular rate can include nondiscretionary bonuses, commissions, shift differentials, and multiple rates; state law or a contract can require a more protective method.
Federal-only boundary
NetPayKit does not currently calculate state income tax, local tax, state disability or paid-leave programs, employer benefits, retirement contributions, garnishments, union dues, or every employer-specific payroll adjustment. It also does not prepare a tax return or replace an official pay stub.
Verification and corrections
We compare published constants with primary federal references and test representative inputs, boundaries, and rounding. See the source register and updates. If an estimate affects a filing, payroll, offer, or legal decision, verify it with the relevant agency or qualified professional.