Bonus Tax 22% vs 37% (2026): When the Federal Withholding Switch Hits

For most people, federal bonus withholding is a flat 22%. For a small group of high earners, an obscure-but-mandatory IRS rule flips a different switch: every dollar of supplemental wages above $1,000,000 in a calendar year — at one employer — is withheld at 37%. This article walks through the rule, the cumulative math, the FICA stacking, and the timing strategies that change a year-end tax bill from a surprise into a plan. If you want the underlying mechanics of why bonuses get withheld at flat rates at all, that lives in our bonus calculator and the why your bonus check looks smaller companion article.

The Rule in One Sentence

Under Treas. Reg. § 31.3402(g)-1(a)(2) and IRS Publication 15: once an employee’s cumulative supplemental wages from a single employer exceed $1,000,000 within one calendar year, every additional dollar of supplemental pay is withheld at a flat 37% federal rate. Below the $1M line, the employer may use the percentage method (22% flat) or the aggregate method. Above the line, the 37% flat is mandatory — no employer discretion, no W-4 override.

What Counts (and What Doesn’t) Toward the $1M

The threshold counts supplemental wages, not all compensation. From IRS Pub 15, supplemental wages include:

• Cash bonuses and incentive payouts
• Commissions
• RSU and stock-award vesting income (FMV at vest)
• Severance pay
• Back pay and retro pay
• Awards and prizes paid through payroll
• Accumulated PTO/vacation payouts
• Lump-sum overtime payments
• Taxable expense reimbursements (non-accountable plan)

Excluded: regular base salary, even at very high levels. A $750,000 salary with a $400,000 bonus is below the threshold ($400,000 in supplemental); a $200,000 salary with a $1.1M bonus is above it ($1.1M in supplemental, $100K excess subject to 37%). The interplay matters most for executives, sales VPs on heavy commission, and finance/legal partners with year-end distributions.

The Math: Withholding on a $1.5M Bonus

Assume a $1.5M cash bonus paid in December to an employee whose YTD supplemental wages from the same employer are $0 before the bonus. The bonus crosses the line at $1,000,000.

The 37% federal flat applies only to the $500K above the line. The first million is still at 22%. Run your own numbers — gross, YTD supplemental, and state — through the bonus calculator to see your specific outcome. The state half of the math is covered in detail in the state-by-state bonus tax breakdown.

How Cumulative Tracking Actually Works

Employers track supplemental wages on a calendar-year, single-employer basis. The IRS rule does not aggregate across employers; if you change jobs in July, the new employer’s supplemental counter starts at zero on the date of hire. Your total tax liability for the year does aggregate, however, so the withholding under-collects relative to a single-employer scenario — meaning you may owe at filing.

For multi-entity employers (e.g., a parent company with several subsidiaries that issue separate W-2s), each W-2-issuing entity is technically a separate employer for withholding purposes. The IRS will collect the right total income tax at filing time, but mid-year withholding can fall short. Track this manually if your compensation is split across related entities.

FICA Stacking: The Often-Missed Bite

The 37% federal flat is the headline, but the payroll tax stack matters too. Above the $200,000 YTD Medicare wage threshold (single filer) or $250,000 (joint), the Additional Medicare Tax of 0.9% kicks in on the wages above the threshold. Combined with regular 1.45% Medicare, that is 2.35% Medicare on top of the 37% federal flat. Social Security caps at the 2026 wage base of $184,500, so a six-figure earner is usually already past the SS cap by the time the big bonus hits in December. See IRS Additional Medicare Tax Q&A for the formal rules.

Three Timing Strategies That Actually Work

The $1M threshold creates real planning leverage. Executives and compensation committees use three patterns:

1. Cross-year splits. Pay $700K in late December and $700K in early January. Neither year crosses the $1M line at the same employer; both are withheld at 22% flat plus payroll taxes. Requires a written deferral or installment agreement executed before constructive receipt.
2. Multi-entity allocation. Compensation paid through related but separate W-2-issuing entities can independently use the 22% flat rate up to $1M each. Requires legitimate economic substance — purely paper structures invite IRS scrutiny.
3. Stock-based deferral. RSUs with delayed vesting (or NQDC plans under IRC § 409A) spread supplemental income across years. Vesting in March and December lands the income in different calendar years if scheduled accordingly.

None of these reduce total tax — they only smooth withholding. The final tax liability is settled at filing. But avoiding the 37% over-withholding can free up six figures of working capital across the calendar year, particularly when combined with quarterly estimated tax planning (see our quarterly estimated tax guide for the safe harbor mechanics).

What If Your Marginal Rate Is Not 37%?

The 37% withholding is mandatory but may exceed your actual marginal tax rate. The 2026 top federal bracket (37%) starts at $626,350 taxable income for single filers and $751,600 for joint filers. If your total taxable income lands below those thresholds — for example, because you have significant pre-tax 401(k), HSA, and itemized deductions — your marginal rate may be 35% (or lower), and you will receive the difference as a refund at filing.

The over-withholding is a cash flow cost. For a $500K bonus above the line, withholding at 37% vs an actual 35% marginal rate costs you $10,000 of interest-free loan to the IRS for ~4 months. Many high earners offset this by reducing W-4 withholding on remaining regular paychecks in the same calendar year — but only up to the safe harbor rule (110% of last year’s total tax for high earners, or 90% of current year), or you face underpayment penalties. The W-4 mechanics are covered in our when to update your W-4 guide.

State Supplemental Stacks Independently

The 37% federal flat does not change state supplemental rules. California still uses 10.23% supplemental for stock-based comp and 6.6% for cash bonuses, regardless of the federal threshold. New York uses graduated brackets that reach 9.65% for high earners; New Jersey at the top tier reaches 9.97% supplemental. Florida, Texas, Washington, Nevada, Wyoming, South Dakota, and Tennessee impose 0% state income tax — so the federal-only 37% withholding leaves materially more in the paycheck in those states. The full state matrix sits in the state-by-state bonus tax breakdown; the related state-by-state take-home pay analysis covers how this stacks against regular salary.

The Bottom Line

The 22%-to-37% supplemental withholding switch is a per-employer, calendar-year, cumulative rule. It applies only to wages above the $1M line, not to the first million. FICA stacks independently (capped SS, uncapped Medicare + 0.9% Additional Medicare). Strategic options exist but reduce withholding, not tax liability: cross-year splits, multi-entity allocation, and stock-based deferral. State supplemental withholding rules apply on top of the federal flat and vary from 0% (FL, TX, others) to nearly 11% (CA stock comp).

Run the math for your specific situation. The PayScale Pro bonus calculator applies the 22% / 37% split based on your YTD supplemental wages and your state, and shows the FICA and state stacks line by line. Cross-check the take-home against your normal paycheck with the take-home pay calculator, and if you also run freelance income on the side, the body recomp calculator at fit.thicket.sh is a useful unrelated tool for the human side of large bonuses (a six-figure bonus and a recomp goal go together more often than most CFOs would predict).