For workers counting on a year-end windfall, how the IRS treats a bonus can matter as much as the size of the check. The tax rules for 2025 and 2026 hinge on whether that bonus is handled as “supplemental wages” with a flat rate or folded into regular pay, and withholding on a bonus often feels harsher than the tax that is actually owed at filing time.
With Congress keeping the current income tax brackets in place for those years, the main moving parts are how employers withhold on bonuses, how Social Security limits apply, and how a higher standard deduction cushions the impact. Understanding those mechanics can be the difference between a bonus that supports savings goals and one that seems to vanish into an unexpected tax bill in April.
What counts as a bonus for tax purposes
For federal tax purposes, bonuses are treated as “supplemental wages.” Treasury regulations under 26 CFR § 31.3402(g)-1, available through the electronic code, explain that bonuses fall into this supplemental wage category, which makes them different from regular salary or hourly pay for withholding rules.
Those same regulations describe how employers may handle supplemental wage payments, including bonuses, when they are paid separately or together with regular wages. Under section 31.3402(g)-1, employers can use an aggregate procedure that combines the bonus with normal wages for the period, or they can rely on flat-rate withholding rules that apply only to supplemental wages, which can make bonus checks feel more heavily taxed even when the final liability is the same.
The 22% flat rate and the $1,000,000 cliff
When a bonus is paid on its own, many employers use a flat federal income tax withholding rate. The IRS employer guide in Publication 15 states that supplemental wages such as bonuses can be subject to a 22% flat rate when the flat method is used. That 22% is not the worker’s actual tax rate; it is a withholding shortcut that treats the entire bonus as if it sits in a middle band of the tax system, even if the person’s true income falls in a lower or higher bracket.
High earners face a second threshold that can change how a very large bonus is handled. Under the Treasury rules in section 31.3402(g)-1, mandatory flat rate withholding applies to supplemental wage payments over $1,000,000 in a calendar year, and the portion above that amount must be withheld at 37%. The IRS has confirmed in its Internal Revenue Bulletin that individual income tax rates include 10%, 12%, 22%, 24%, 32%, 35%, and a top rate of 37%, and that the $1,000,000 amount used in this supplemental wage rule is not inflation-adjusted before 2027, so the 37% withholding cliff stays fixed for 2025 and 2026.
How the aggregate method really works
Not every bonus is taxed at a flat 22%. When an employer combines a bonus with regular wages in a single paycheck, the withholding can be calculated using the same progressive system that applies to normal pay. The IRS explains in Publication 15-T that employers compute withholding using either the percentage method or wage bracket tables when supplemental wages are aggregated with regular wages.
In practice, payroll looks at year-to-date taxable wages, adds the bonus, and then applies the tax tables as if that combined amount were regular pay for the period. Because the rate tables keep the 10%, 12%, 22%, 24%, 32%, 35%, and 37% brackets in place for 2025 and 2026, this aggregate approach applies those different rates across the combined amount, which can reduce the risk of having too much withheld for workers whose overall income would otherwise fall below the flat 22% level.
Social Security limits and your 2026 bonus
Income tax is only part of the story. For many workers, a bonus also interacts with Social Security payroll tax rules, which hinge on a yearly cap. The Social Security Administration press release on the 2026 cost-of-living adjustment, available on the SSA site, explains that benefits will rise by 2.8% for 2026 and that the same announcement states the Old-Age, Survivors, and Disability Insurance (OASDI) taxable maximum for 2026 and compares it to 2025.
That taxable maximum is the ceiling on earnings subject to the 6.2% OASDI tax, and it applies to bonuses as well as regular wages in each calendar year. Once combined wages and bonuses reach the OASDI taxable maximum for 2026, any additional earnings, including a late-year bonus, are not subject to the 6.2% Social Security portion of payroll tax, although Medicare tax rules still apply to all covered wages.
Standard deduction, brackets and real tax cost
The way a bonus feels on payday can be very different from its final tax cost once a return is filed, especially when the standard deduction rises. The IRS announcement on tax inflation adjustments for 2026 explains that the law often called the One Big Beautiful Bill raises the standard deduction amount to $31,500 for married couples filing jointly for tax year 2025, and the same inflation adjustment release describes how standard deduction amounts and bracket thresholds are adjusted for 2026.
The IRS uses the Internal Revenue Bulletin to confirm that the individual rate structure of 10%, 12%, 22%, 24%, 32%, 35%, and 37% remains in effect, so a bonus in 2025 or 2026 fits into the same bracket system as regular income. When withholding on a bonus is locked at 22% using the flat method, workers whose true marginal rate is 10% or 12% may see refunds because too much was withheld, while those in the 32%, 35%, or 37% brackets may owe more at filing time because the 22% flat rate did not match their actual liability.
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*This article was researched with the help of AI, with human editors creating the final content.
Julian Harrow specializes in taxation, IRS rules, and compliance strategy. His work helps readers navigate complex tax codes, deadlines, and reporting requirements while identifying opportunities for efficiency and risk reduction. At The Daily Overview, Julian breaks down tax-related topics with precision and clarity, making a traditionally dense subject easier to understand.
