Short Answer

The flat withholding rate for most federal income tax on bonuses is 22%. This applies to supplemental wages such as one-time bonuses or incentive payments under $1 million.

For bonuses over $1 million, the flat rate increases to 37%. Employers also deduct Social Security, Medicare, and any applicable state and local taxes, so the net bonus is less than the gross amount received.

Detailed Explanation:

Flat withholding rate for bonuses

Definition

The flat withholding rate is a fixed percentage applied to supplemental wages, including bonuses, to calculate federal income tax withheld. This method simplifies withholding for one-time or irregular payments separate from regular wages.

Standard rate for most bonuses

For most bonuses under $1 million, the IRS requires employers to withhold 22% of the bonus amount for federal income tax. This rate is applied directly to the gross bonus and does not consider regular wages or W-4 allowances, making it a straightforward approach for employers.

Higher rate for large bonuses

Bonuses exceeding $1 million in a single payment are subject to a 37% flat withholding rate. This higher rate ensures that sufficient federal tax is withheld on very large supplemental payments and reduces the likelihood of underpayment penalties.

Other payroll taxes

Social Security and Medicare

In addition to federal income tax, bonuses are subject to Social Security tax (6.2% on wages up to the annual limit) and Medicare tax (1.45%, with an additional 0.9% for high-income earners). These amounts are withheld alongside the federal flat rate.

State and local taxes

State and local income taxes may also apply to bonuses. Each state has its own rules, and employers deduct these taxes along with the federal flat rate to calculate the net bonus paid to employees.

Methods for calculating withholding

Flat rate method

The flat rate method applies 22% (or 37% for large bonuses) directly to the gross bonus amount. This is simpler than combining the bonus with regular wages for payroll withholding. Most employers use this method for ease and accuracy.

Aggregate method

Alternatively, some employers use the aggregate method, combining the bonus with regular wages and calculating withholding based on the total pay for the period and W-4 information. This method may result in higher or lower withholding than the flat rate, depending on your regular income and allowances.

Importance of understanding the flat rate

Take-home pay planning

Knowing the flat withholding rate helps employees estimate the net bonus they will receive. Taxes and payroll deductions significantly reduce take-home pay, so planning is important for budgeting and financial decisions.

Avoiding surprises

Using the flat rate ensures consistent federal tax withholding on bonuses. Understanding this prevents surprises when calculating total tax payments and avoids underpayment penalties.

Adjusting W-4 for combined income

Employees who receive multiple bonuses or have additional income should review their W-4 to make adjustments if needed. Proper W-4 completion ensures withholding is balanced across all income sources.

Practical examples

• A $5,000 bonus under $1 million: 22% federal tax = $1,100 withheld, plus Social Security and Medicare taxes.
• A $2,000,000 bonus over $1 million: 37% federal tax = $740,000 withheld, plus other payroll taxes.
• State taxes further reduce the net payment depending on state regulations.

Conclusion

The flat withholding rate for most bonuses under $1 million is 22%, while bonuses over $1 million are withheld at 37%. This rate ensures accurate federal tax withholding on supplemental wages. Social Security, Medicare, and state taxes also apply. Understanding the flat rate helps employees plan take-home pay, avoid surprises, and maintain compliance with IRS rules.