How a paycheck estimate is built

Start with gross pay for one pay period

For a salary, gross pay is generally the annual salary divided by the number of pay periods. Weekly, biweekly, semimonthly, monthly, and annual schedules therefore produce different per-check gross amounts even when annual salary is unchanged. For hourly work, gross pay depends on the hourly rate, hours worked, pay schedule, and any modeled overtime or supplemental wages.

Pre-tax deductions do not all behave the same way

A deduction can reduce federal income-tax wages without reducing Social Security or Medicare wages, while some qualifying benefit deductions can reduce both. That distinction matters because two employees with the same gross pay and the same deduction amount may still have different FICA results depending on the type of deduction.

Federal income-tax withholding

Federal withholding is not simply “salary multiplied by a tax bracket.” Payroll withholding annualizes wages and applies the withholding method associated with the employee's Form W-4 elections. Credits, multiple-job elections, other income, deductions, and extra withholding can all change the amount withheld from a single check.

PayCalc's 2026 paycheck engine models the applicable Publication 15-T percentage-method workflow for the supported W-4 inputs. Separately identified supplemental wages can use a different federal withholding method from regular wages.

Social Security and Medicare

Social Security and Medicare are separate from federal income-tax withholding. Social Security is subject to an annual wage base, so year-to-date wages matter near the cap. Medicare does not use the same wage cap, and Additional Medicare withholding can begin after the applicable employer withholding threshold is crossed.

State and local rules

State withholding is not uniform. Some states have no wage income tax, some use flat rates, and others use withholding tables, allowances, filing-status choices, or state-specific certificates. Certain states also impose employee payroll programs separate from income tax. Local withholding can also apply in some jurisdictions.

Why the result may differ from a real paycheck

An employer's payroll system may have more information than a public calculator: exact year-to-date wages, benefit-plan tax treatment, local work and residence rules, reciprocity certificates, garnishments, employer-paid premiums, specialized compensation, and rounding rules. Use the result as a planning estimate and compare it with the pay stub or payroll provider when exact reconciliation matters.

Ready to calculate? Open the 2026 Paycheck Calculator, or review the detailed PayCalc methodology.