The IRS defines supplemental wages as compensation paid to an employee that is not regular wages. Regular wages are payments made for a specific payroll period at an hourly rate or salary. Hours paid at minimum wage (Option C) represent the base regular earnings for work performed and do not qualify as supplemental. In contrast, supplemental wages include items such as bonuses, commissions, overtime pay (Option D), severance pay (Option B), and payouts for accrued vacation or sick leave (Option A). This distinction is critical for federal income tax withholding because employers have the option to use a flat supplemental withholding rate (currently 22%) on these amounts if they have already withheld income tax from the employee ' s regular wages. Correctly identifying supplemental pay ensures compliance with IRS Publication 15 and prevents the under-withholding of taxes on non-regular compensation.