How to Handle Supplemental Wage Payments: Bonuses, Commissions, and Severance
5/12/2026
Supplemental wages are where routine payroll produces non-routine mistakes. The withholding rules are genuinely simple — there are two methods and one mandatory override. The problems come from everything that happens around the payment: the overtime it retroactively changes, the deposit threshold it trips, the wage base it crosses, and the employee expectation it violates.
This guide covers the withholding mechanics first, then the four second-order effects that cause most of the damage.
What Counts as a Supplemental Wage
Supplemental wages are compensation paid in addition to regular wages. The category is broad:
- Bonuses of all kinds — signing, performance, retention, referral, holiday, spot
- Commissions
- Overtime paid in a separate check from regular wages
- Severance pay
- Back pay and retroactive pay increases
- Accumulated sick or vacation payouts
- Awards and prizes
- Taxable fringe benefits and imputed income
- Non-deductible moving expense reimbursements
- Payments for non-competition agreements
- Certain equity compensation events
Note what is not on the list: regular wages, however large, and regular commissions that constitute the employee's entire compensation. If commissions are the employee's only pay, they are generally regular wages, not supplemental — a distinction that changes the available withholding method.
The Two Withholding Methods
Optional Flat Rate: 22%
If the supplemental payment is identified separately from regular wages, the employer may withhold federal income tax at a flat 22%, with no reference to the employee's Form W-4.
Conditions and consequences:
- The employee's W-4 is disregarded entirely — including additional withholding they requested and any extra amount they specified
- The employee cannot elect a different flat rate, and the employer cannot agree to one
- It applies only if income tax was withheld from the employee's regular wages at some point in the current or prior year
- It is a withholding rate, not a tax rate. The actual liability is settled on the employee's return.
That last point is the source of most complaints. An employee in a marginal bracket above 22% is under-withheld and may owe at filing; an employee in a lower bracket is over-withheld and receives a refund. Both call payroll to report an error that is not one.
Aggregate Method
Combine the supplemental payment with regular wages for the payroll period and withhold as if the total were a single regular payment, using the employee's W-4 and the applicable tables.
This method is required when the supplemental payment is not identified separately, and it is generally the better choice when:
- You want withholding to approximate the employee's actual liability
- The employee has requested additional withholding you would otherwise ignore
- The payment is modest relative to regular wages
The aggregate method can produce a startlingly high withholding figure on a large bonus, because the payroll system annualizes the combined amount as though the employee earned that much every period. The math is correct and the employee's refund will reflect it, but the explanation needs to be ready before the paycheck lands.
The Mandatory $1,000,000 Rule
Supplemental wages exceeding $1,000,000 to a single employee in a calendar year must be withheld at the highest income tax rate — currently 37% — on the amount above $1,000,000. This is mandatory:
- No flat-rate option, no aggregate option, no W-4 consideration
- The threshold is cumulative across the calendar year, not per payment
- It applies per employer, and the count includes all supplemental payments made during the year
This rule catches companies during acquisitions, large severance events, and equity vesting. Track cumulative supplemental wages per employee — the payment that crosses the threshold may be split, with the portion below $1,000,000 withheld at 22% and the excess at 37%.
Our Paycheck Fundamentals Training & Certification Program covers the calculation, and IRS taxation rules for highly compensated employees covers the high-earner mechanics.
FICA and Everything Else Still Applies
The flat-rate election affects federal income tax withholding only. Everything else operates normally:
- Social Security at 6.2% until the employee reaches the 2026 taxable maximum of $184,500
- Medicare at 1.45% with no limit
- Additional Medicare at 0.9% once cumulative wages exceed $200,000
- FUTA and state unemployment until the respective wage bases are reached
- State income tax, using each state's own supplemental rules — many states have their own flat supplemental rate, some require the aggregate method, and some have no separate provision at all
- Garnishments, which apply to supplemental wages as they do to regular wages
A bonus is frequently the payment that pushes an employee across the Social Security wage base or the $200,000 Additional Medicare threshold mid-year. Both need to be handled in the same run.
The Four Second-Order Effects
This is where the real exposure sits.
1. Non-Discretionary Bonuses Change Overtime Retroactively
A non-discretionary bonus paid to a non-exempt employee must be included in the regular rate for overtime purposes. If the bonus covers a period longer than the pay period, it must be allocated back across the weeks it was earned, retroactively raising the regular rate in each week — and additional overtime premium is owed for every one of those weeks in which the employee worked over 40 hours.
A quarterly production bonus paid to non-exempt employees therefore generates a retroactive overtime calculation across thirteen weeks. Most payroll systems do not do this automatically.
Which bonuses are excludable? Genuinely discretionary ones — where the fact of payment, the amount, and the timing are all at the employer's sole discretion and not promised in advance. The moment a bonus is announced, promised, or tied to a formula, it becomes non-discretionary and enters the regular rate. Employers routinely call bonuses discretionary while describing the qualifying criteria in the announcement email, which is the opposite of discretionary.
See our Payroll Wage & Hour Training & Certification Program and the DOL rules on overtime session.
2. Bonus Runs Trip the $100,000 Deposit Rule
Any time accumulated employment tax liability reaches $100,000, the deposit is due the next business day — regardless of whether you are normally a monthly or semi-weekly depositor. It also promotes the employer to semi-weekly status for the remainder of the year and all of the following year.
A single annual bonus payroll can do this to a company that has been comfortably monthly for a decade. Calculate the accumulated liability before releasing the run, not after, and build a standing rule that any off-cycle or unusually large payroll gets a deposit-timing review.
Failure-to-deposit penalties reach 10% at ten days, and the Trust Fund Recovery Penalty allows personal assessment against responsible individuals. See How To Minimize And Eliminate Payroll Penalties.
3. Retroactive Pay Is Not Just the Base Difference
A retroactive raise owes the straight-time difference plus additional overtime premium for any affected week in which the employee worked overtime, because the increase raises the regular rate for those weeks. Systems commonly pay the base difference and stop.
Retro pay is taxed in the period paid, not the period earned, so a retroactive increase paid in January covering December wages does not reopen the prior year's Form W-2.
4. Severance Has Its Own Complications
Severance is supplemental wages subject to income tax withholding and FICA. Beyond the withholding:
- Payments may implicate Section 409A if structured as deferred compensation, with severe consequences for missteps
- A release of claims has its own timing and consideration requirements under age discrimination law
- Continued health coverage interacts with COBRA notice obligations
- State final-pay deadlines may govern when severance must be paid, depending on how the agreement is structured
- Severance paid in a year after termination still generates a Form W-2, not a Form 1099
Never process a severance arrangement from the payroll side alone. Confirm the structure with counsel first.
New for 2026: Bonuses Are Not Qualified Overtime
Under the One Big Beautiful Bill Act, individuals may deduct qualified overtime compensation for tax years 2025 through 2028, and beginning with the 2026 tax year employers must separately report qualified overtime on Form W-2.
The point relevant here: overtime-style bonuses do not qualify. Only the premium portion of overtime mandated by Section 7 of the FLSA counts. A bonus that rewards extra hours, a shift premium, or an incentive tied to weekend work is not qualified overtime no matter what it is called internally.
This creates a real coding discipline problem. If your system lumps premium-style bonuses into an overtime earnings code, you will over-report qualified overtime on the W-2. See our OBBBA payroll forms update session.
A Pre-Bonus-Run Checklist
Before releasing any supplemental payroll:
- Confirm each payment is identified separately if you intend to use the 22% flat rate
- Check cumulative supplemental wages per employee against the $1,000,000 threshold
- Determine which bonuses are non-discretionary and require regular-rate inclusion
- For multi-week non-discretionary bonuses paid to non-exempt staff, compute the retroactive overtime
- Identify anyone who will cross the Social Security wage base or the $200,000 Additional Medicare threshold
- Calculate accumulated deposit liability and check the $100,000 next-day rule
- Confirm the state supplemental withholding method for each work state
- Confirm garnishment orders are applied to the supplemental payment
- Verify the earnings code does not misclassify a premium bonus as qualified overtime
- Prepare the employee communication explaining why withholding looks the way it does
Our Payroll Reconciliation And Reporting session covers the post-run tie-out.
Frequently Asked Questions
What is the supplemental wage tax rate for 2026?
The optional flat rate for federal income tax withholding on supplemental wages is 22%, available when the payment is identified separately from regular wages. Supplemental wages exceeding $1,000,000 to one employee in a calendar year must be withheld at 37% on the excess, with no optional method available. These are withholding rates, not tax rates — the employee's actual liability is settled on their return.
How are bonuses taxed on a paycheck?
A bonus is supplemental wages. The employer either withholds federal income tax at the 22% flat rate, if the bonus is identified separately, or uses the aggregate method, combining it with regular wages and applying the employee's Form W-4. Social Security, Medicare, Additional Medicare, unemployment taxes, and state withholding all apply normally regardless of which federal method is used.
Can an employee choose how their bonus is taxed?
No. The employer selects between the flat rate and the aggregate method, and the employee cannot elect a different rate. Under the flat-rate method the employee's W-4 is disregarded entirely, including any additional withholding they requested. An employee who wants more withheld can adjust their W-4 for regular wages, but not for the flat-rate supplemental payment.
Do bonuses affect overtime pay?
Non-discretionary bonuses do. They must be included in the FLSA regular rate, and a bonus covering more than one pay period must be allocated back across the weeks earned, retroactively raising the regular rate and generating additional overtime premium for each week the employee exceeded 40 hours. Only genuinely discretionary bonuses — where the fact, amount, and timing are entirely at the employer's discretion and not promised in advance — are excludable.
What is the difference between the flat rate and aggregate method?
The flat rate applies a fixed 22% to the supplemental payment and ignores the employee's W-4. The aggregate method combines the supplemental payment with regular wages for the period and withholds as though the total were one regular payment, using the W-4 and the withholding tables. The aggregate method is required when the payment is not identified separately, and it tends to approximate actual liability more closely — though on a large bonus it can produce a high figure because the system annualizes the combined amount.
Is severance pay taxed differently than regular wages?
Severance is supplemental wages, so the same withholding methods apply, and it remains subject to Social Security and Medicare. It is reported on Form W-2 even if paid in a year after termination. The complications are structural rather than arithmetic — potential Section 409A deferred compensation issues, release-of-claims timing requirements, COBRA interaction, and state final-pay deadlines — which is why severance should be reviewed with counsel before processing.
Going Deeper
Flat rates and thresholds are set federally and can change with tax legislation; state supplemental rules vary widely. Verify current figures against IRS Publication 15 and each state's agency before your first bonus run of the year.
