The tax withheld from bonus income is often more than the tax withheld from your regular pay. Your payroll department either withholds tax on your bonus income at a flat rate or applies your regular rate to your combined salary and bonus income. Although your regular rate is applied in this scenario, combining your salary and bonus on one check could put you in a higher withholding bracket, causing the tax allocated to your bonus to actually be higher than the regular rate. However, you’re allowed to adjust your withholding any time by simply providing a new withholding allowance certificate to your payroll department.
Ask your payroll department if your bonus check will be paid separate from your regular paycheck or if your bonus and regular pay will be combined on one check. Each method has different income tax withholding rules, so you’ll need this information to perform an appropriate adjustment.
Download Form W-4 from the Internal Revenue Service website. Complete sections 1 through 3 with your name, address, Social Security number and marital status.
Calculate withholding adjustments. If your employer issues separate bonus checks that do not include
any regular wages, your employer withholds income tax at a flat rate of 25 percent. This rate is automatic, which means the marital status and number of allowances you normally claim are irrelevant. In this case, write “Exempt” on line 7. This is the only withholding adjustment you can make to separate bonus check payments.
If your employer combines regular wages with your bonus income, gather your most recent pay stub and use the IRS Withholding Calculator on the IRS website to estimate the number of allowances you should claim. The calculator asks for an estimate of the federal income tax withheld from your pay to date, including bonuses. Estimate that the amount withheld from your bonus will be 20 percent. If the calculator results show you should adjust your W-4 allowances, you’ll see a message with the number of allowances to claim on line 5 of your W-4.
Sign and date your new W-4 form. Give the form to your payroll department as soon as possible before your bonus check payments. Check with your payroll department for time restrictions, as many companies need at least one to two pay periods to process new W-4 information.