The IRS views any bonus you receive as wages. This means that almost all bonuses are taxed.One of the most effective ways to reduce taxes on a bonus is to reduce your gross income with a contribution to a taxdeferred retirement account. A W4 form, or "Employee's Withholding Certificate," is an IRS tax document that employees fill out and submit to their employers. The short answer is yes, bonuses are taxable, meaning you must pay the corresponding taxes on them. So, how do you report a bonus on your taxes? State agencies may use recruitment or retention bonuses to provide additional financial incentives to attract, hire or retain eligible key classified staff. In today's video, I'm going to walk you through the process of filling out the IRS Form W-4, specifically when you're dealing with bonus pay. You filled out a W-4 form when you were hired. The W4 form determines the amount of federal income tax withheld from your paycheck.