Last updated: April 2026

Supplemental Wages Tax Withholding: The 22% Rule and Its Traps

Use the 22% flat rate on supplemental wages tax whenever you can. It is cleaner, faster, and protects you from angry April phone calls.

The IRS defines supplemental wages as compensation paid outside a regular paycheck cycle. Bonuses, commissions, severance, retroactive pay, accumulated sick leave payouts, moving expense reimbursements, prizes, awards, and overtime recalculated on a nondiscretionary bonus all qualify. Regular hourly or salary wages do not.

That distinction controls which withholding method you are allowed to use, and it decides whether your employee gets a refund or a surprise bill.

What Counts as a Supplemental Payment

Publication 15 lists the categories clearly. A year-end bonus is supplemental. Sales commissions paid on a separate check are supplemental.

Severance is supplemental. A retro pay adjustment for a raise backdated three pay periods is supplemental. Back pay from a settlement is supplemental.

Tips reported by employees are supplemental when paid outside the normal cycle. Taxable fringe benefits such as personal use of a company car become supplemental when you run them through payroll as a lump sum at year end.

Regular pay does not convert into supplemental compensation just because you paid it late. A missed paycheck processed two days after the normal run is still regular wages, withheld at the employee's W-4 rate.

The exception: if you combine the late regular pay with a bonus on one check and do not separately identify the amounts, the IRS treats the entire payment as supplemental. Separate the line items on the stub and you keep the regular portion under normal withholding.

The 22% Flat Rate, and Why It Is Optional

Under $1 million in cumulative supplemental payments per employee per calendar year, you have a choice. You can withhold a flat 22% federal income tax on the bonus or commission check. The alternative is the aggregate method, which runs the payment through normal W-4 tables as if it were a larger regular paycheck.

The flat rate is optional. Many payroll systems default to it because it is simpler and more defensible in an audit. Gusto defaults to 22% on bonus runs. Rippling asks you per run. ADP lets you configure it at the earnings-code level, which is where mistakes hide.

Once an employee crosses $1 million in supplemental payments during the calendar year, the rule changes. Every dollar above that threshold must be withheld at 37%, the top federal bracket. This is not optional. It is not negotiable. It applies even if the employee's marginal rate is lower, and the employee recovers any overwithholding on their 1040.

The tradeoff on the flat method is real. A worker in the 12% bracket getting a $3,000 holiday bonus loses $660 to federal withholding instead of roughly $360 under aggregate. That worker will see the money back at tax time, but the paycheck sting is immediate.

The flat rate is the safer default. The aggregate method is the quieter killer.

The Aggregate Method Gotcha That Causes April Surprises

Here is the trap that shows up every April in my inbox.

An employer chooses the aggregate method because it sounds more accurate. Payroll takes the bonus, adds it to the employee's most recent regular paycheck, looks up the combined amount in the withholding tables, subtracts what was already withheld on the regular check, and withholds the difference on the bonus.

That math works cleanly for small bonuses. It breaks badly on large ones. A $40,000 executive bonus added to a $4,000 biweekly paycheck produces a table lookup that assumes the employee earns $44,000 every two weeks, or $1.14 million annually. The table withholds accordingly, often at a blended rate close to 32%, which is above where most recipients actually land.

Now flip it. An employee in a genuinely high bracket receives a bonus under the aggregate method when their Form W-4 claims dependents, a second job adjustment, or extra allowances that reduce table withholding. The aggregate calculation under-withholds against their real marginal rate. April arrives. The employee owes $8,000 and blames payroll.

The 22% flat rate protects against this. It is blunt but predictable.

State Supplemental Rates That Break the Federal Pattern

Federal withholding is only half the story. Twenty-two states plus DC publish their own flat supplemental rate that differs from their regular income tax tables. The rest default to aggregate or do not tax wage income at all.

California runs 6.6% on most bonuses and 10.23% on stock options and bonus payments treated as wages for equity compensation. That 10.23% catches startups every grant cycle. New York uses 11.7% for most supplemental payments.

Georgia uses a flat 5.39% in 2026 after its rate reduction. Minnesota sits at 6.25%. Vermont runs 30% of federal, which is an unusual construction.

Nine states have no wage income tax at all: Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington, and Wyoming. Bonuses paid to residents of those states carry zero state withholding regardless of method.

The limitation worth naming: state supplemental rates apply only when you are using the flat method federally. If you use aggregate federally, most states require aggregate at the state level too. Mixing methods across jurisdictions creates reconciliation headaches on the W-2.

For current rates by state, see our 2026 payroll tax rates guide.

How Form W-4 Interacts With Bonus Checks

The 2020 W-4 redesign changed how bonuses behave under the aggregate method. The old form used allowances. The current form uses dollar adjustments for dependents, other income, deductions, and extra withholding.

When a bonus runs through aggregate, the payroll system applies the employee's Step 3 dependent credit and Step 4 adjustments to the combined wage amount. A worker claiming $6,000 in dependent credits gets that credit applied against the table lookup, which reduces withholding on the bonus disproportionately.

Employees who want more withheld on bonuses have a cleaner path. They can file a new W-4 with an additional amount in Step 4(c) that applies to every paycheck including the bonus run. They can also ask payroll to use the 22% flat method specifically on their bonus. Most payroll platforms honor a per-run override.

The flat rate ignores W-4 entries entirely. A worker with five dependents and a $10,000 bonus loses exactly $2,200 to federal withholding under the flat rule. Their W-4 does not matter on that check. It matters on their 1040 when they reconcile the year.

FICA, Medicare, and the Other Taxes People Forget

The 22% rule covers federal income tax only. Social Security and Medicare still apply to supplemental payments at the normal rates: 6.2% Social Security up to the 2026 wage base of $176,100, and 1.45% Medicare with no cap. An additional 0.9% Medicare surtax kicks in on wages above $200,000 for a single filer, which payroll must withhold starting with the paycheck that crosses the threshold.

FUTA applies to the first $7,000 of wages per employee, so most bonuses paid mid-year or later carry no federal unemployment cost. State unemployment depends on the state wage base, which in Washington exceeds $68,000 in 2026 and in Florida sits at $7,000. A December bonus in Florida is free of SUTA. The same bonus in Seattle probably is not.

Retirement plan deferrals also apply unless the plan document excludes bonuses from the definition of compensation. Most 401(k) plans include bonuses by default, which means a 6% deferral election pulls $600 out of a $10,000 bonus before federal withholding hits the rest.

Overtime on Retroactive Bonuses: The Hidden Liability

A nondiscretionary bonus tied to production, attendance, or performance must be included in the regular rate of pay for overtime calculations. If the bonus covers a period during which the employee worked overtime hours, you owe additional overtime pay on the bonus itself.

The math: take the bonus, divide by the total hours worked in the bonus period, multiply by 0.5, and multiply by the overtime hours in that period. That additional overtime is itself supplemental compensation, withheld under the same 22% or aggregate rule you chose for the bonus.

Miss this calculation and you face FLSA back wage liability plus liquidated damages equal to the unpaid amount. DOL audits in construction and manufacturing flag this consistently. For the mechanics, read our guides on nondiscretionary bonus overtime and the regular rate of pay.

Discretionary bonuses, true holiday gifts with no performance strings attached, are excluded from the regular rate. The exception is narrower than most employers assume. If your handbook promises a year-end bonus based on company results, it is not discretionary.

When the Flat Method Is the Wrong Call

Three situations flip my default recommendation.

First, a low-income worker receiving a modest bonus. A part-time employee earning $18,000 annually who gets a $500 longevity bonus loses $110 to the flat rule against a true tax liability near zero. They will recover it in April, but if they needed the cash for rent, the aggregate method would have withheld almost nothing and served them better.

Second, an employee who has specifically requested aggregate treatment in writing and understands the April reconciliation. Honor the request and document it.

Third, states where the flat federal choice forces an unfavorable state calculation. New Jersey and Oregon residents sometimes see better outcomes under aggregate because state supplemental treatment runs through their progressive tables more smoothly.

Everyone else should get the flat rate. It is predictable, it passes audit, and it keeps April quiet.

Your Action Checklist Before the Next Bonus Run

Pull up your payroll platform right now and check three settings.

One: verify the default federal withholding method on your bonus earnings code. In Gusto, it is under Company Settings then Earning Types. In ADP Workforce Now, it is under Setup then Earnings. In Paychex Flex, it is in the pay type configuration. Set it to 22% flat unless you have a documented reason otherwise.

Two: confirm your state supplemental rate is current for 2026. Rate changes took effect January 1 in at least eight states this year. An outdated rate causes state reconciliation gaps that surface on the fourth quarter filing.

Three: identify any employee who will cross $1 million in cumulative supplemental payments this year. The mandatory 37% rate applies to every dollar above the threshold, and missing it exposes you to penalties under IRC Section 3509. Flag those workers in your system before their next bonus check runs.

For the official rules, read the IRS Publication 15 supplemental wages section. For related guidance on employer tax obligations, start at our payroll tax hub.

This is not legal or financial advice. Consult a qualified professional for your specific situation.