Payroll Calculations and Processing
Calculation questions reward a disciplined gross-to-net process. Identify taxable wages first: start with gross pay, add imputed income (for example, taxable fringe benefits or personal use of a company vehicle), then subtract pre-tax deductions that qualify. Apply federal income tax withholding using the employee's Form W-4, then Social Security and Medicare, then state and local taxes, then post-tax deductions and garnishments.
Know supplemental wages: bonuses, commissions, and overtime premiums may be withheld at the flat supplemental rate or aggregated with regular wages. Trap: the method chosen changes withholding, not the employee's ultimate tax liability. Trap: overtime must be calculated on the regular rate, and nondiscretionary bonuses can increase overtime due. Trap: pretax deductions reduce taxable wages, but employer-paid taxes are not withheld from the employee.
Rounding is a common distractor: be consistent, and do not round intermediate regular rates too early. For gross-ups, divide the desired net by (1 minus the combined tax rate) to find the taxable gross.
Worked example: Gross $2,000; Section 125 health $150; 401(k) $100; federal withholding $120; Social Security 6.2% and Medicare 1.45% on $1,750; state tax $50; post-tax garnishment $75. FICA = $108.50 + $25.38 = $133.88. Net = $2,000 − $150 − $100 − $120 − $133.88 − $50 − $75 = $1,371.12. Check that gross minus all deductions equals net.