A payroll adjustment is a correction or modification to your pay record that happens outside the normal payroll cycle. It might fix a missed overtime entry, apply a raise retroactively, reverse an incorrect deduction, or claw back an overpayment. Whatever the reason, the adjustment changes your gross pay for the affected period, and every tax and deduction tied to that gross figure gets recalculated to match.
Why Payroll Adjustments Happen
Most adjustments trace to a specific triggering event rather than a broken payroll system. The common ones include:
- A missed time card punch, an unapplied shift differential, or overtime hours recorded at the wrong rate.
- A retroactive pay increase, such as a raise approved in March but effective January 1, which requires computing the pay difference across every affected period and paying it as a lump sum.
- Commission left off a paycheck, or a bonus calculated against the wrong sales figures.
- A health insurance premium taken at the wrong tier, a 401(k) contribution percentage that was not updated, or a garnishment applied incorrectly.
- PTO balance corrections, which matter most at termination when many employers owe a payout of unused time.
Retroactive raises are the most calculation-heavy of these because payroll has to work out the old-versus-new rate difference for every past pay period in the gap, then run tax on the resulting lump sum. A raise that crosses a calendar year adds another layer, because the tax treatment can differ by year.
How the Adjustment Changes Your Paycheck
Whether the adjustment adds money or takes it away, the change flows through the same withholding machinery as regular pay. The adjustment first changes your gross pay, and that new gross becomes the starting point for recalculating each tax and deduction line.
Federal Income Tax Withholding
Positive adjustments like retroactive pay, back pay, and bonuses count as supplemental wages under IRS rules. Employers have two ways to withhold federal income tax on supplemental wages. The simpler method is a flat 22% on the supplemental amount. The alternative, the aggregate method, combines the adjustment with your regular wages for the pay period and calculates withholding as if the total were a single payment. The aggregate method sometimes produces higher withholding because it temporarily pushes you into a higher bracket for that paycheck.1Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide
For employees receiving more than $1 million in supplemental wages in a calendar year, the excess is subject to a mandatory 37% withholding rate regardless of the W-4 on file.1Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide
Social Security and Medicare
Whatever income tax method the employer uses, the adjustment is also subject to FICA. Social Security tax is 6.2% on wages up to the annual wage base, and Medicare is 1.45% on all wages with no cap.2GovInfo. 26 USC 3101 – Rate of Tax
The Social Security wage base for 2026 is $184,500.3Social Security Administration. Contribution and Benefit Base If your year-to-date earnings have already hit that ceiling, a positive adjustment will not trigger any additional Social Security withholding. If the adjustment pushes you past $184,500, only the portion below the threshold gets the 6.2% deduction.
High earners also face the Additional Medicare Tax. Once your wages from a single employer exceed $200,000 in a calendar year, the employer must withhold an extra 0.9% on wages above that threshold. A large retroactive payment or bonus that lifts you past $200,000 will pull in this additional withholding on the excess.4Internal Revenue Service. Questions and Answers for the Additional Medicare Tax
Voluntary Deductions
Percentage-based voluntary deductions ride along with the change in gross pay. If you contribute a percentage of each paycheck to a 401(k), a positive adjustment increases the dollar amount going into your account that period. The basic 401(k) elective deferral limit for 2026 is $24,500, and contributions above that must be returned and included in your gross income for the year.5Internal Revenue Service. Retirement Topics – Contributions A large adjustment late in the year is the situation to watch, because it can push a percentage-based contribution over the ceiling.
When the Employer Says You Were Overpaid
When an employer discovers it overpaid you, the correction runs in reverse: a negative adjustment reduces your gross pay on a future paycheck. This is where the rules get legally uneven, because federal and state law diverge.
Under the FLSA, employers are generally permitted to recover overpaid wages through future paycheck deductions. State laws layer additional protections on top. Some states require written authorization from the employee before any deduction can be taken. Others cap the amount that can come out of a single paycheck, with limits ranging from roughly 10% to 15% of gross wages per period. A handful of states effectively prohibit unilateral deductions for overpayments without a signed agreement. Advance notice rules also vary, from no specific requirement to mandatory written notice before the deduction takes effect.
The practical takeaway for employees is that in most states your employer cannot simply slash your next paycheck without warning, even when the overpayment is real. You should expect written notice of the overpayment amount, the dates it occurred, and a proposed repayment schedule, and in many states you have to sign off before anything is deducted.
How the Correction Gets Processed
A significant underpayment is often handled as an off-cycle payment: a separate check or direct deposit issued within a few business days rather than waiting for the next regular payday. Less urgent corrections get folded into the next scheduled payroll run.
Either way, the change should show up in writing. Federal law does not require employers to provide pay stubs, but the vast majority of states mandate itemized wage statements.6U.S. Department of Labor. Fair Labor Standards Act Advisor – Are Pay Stubs Required? A properly documented adjustment shows how the change moved gross pay, each withholding category, and the final net figure. Off-cycle adjustments often appear on a separate pay stub from your regular paycheck, so look for two documents rather than one.
Corrections That Cross a Tax Year
An error caught inside the same calendar year is usually simple to fix: the employer adjusts federal income tax withholding on a current or future paycheck, and year-to-date totals catch up.
Prior-year corrections are more restrictive. The IRS generally limits federal income tax withholding corrections to the same calendar year the wages were paid. For overcollections, the employer can only correct the withholding if it also repaid or reimbursed the employee within that same year.7Internal Revenue Service. Correcting Employment Taxes
When a correction changes wage or tax figures already reported on a W-2 you used to file a prior-year tax return, the employer must issue a corrected Form W-2c. That form shows both the previously reported and the corrected numbers for wages and withholdings, and copies go to you and the Social Security Administration.8Internal Revenue Service. About Form W-2 C, Corrected Wage and Tax Statements If the change materially shifts what you owed or were owed for that year, you may then need to file an amended personal return on Form 1040-X.
If Your Employer Will Not Correct the Error
If you have flagged a payroll error and your employer is not fixing it, document everything in writing: the pay periods affected, the amounts you believe are wrong, and when you first reported the problem. Keep copies of your pay stubs, time records, and any messages about the issue.
If internal channels do not resolve it, you can file a complaint with the U.S. Department of Labor’s Wage and Hour Division online or by calling 1-866-487-9243. The nearest field office will contact you within two business days to discuss your situation and decide whether to investigate. If the investigation finds your employer owes you wages, you will receive a check for the amount owed.9Worker.gov. Filing a Complaint With the U.S. Department of Labor’s Wage and Hour Division
You can also file a private lawsuit under the FLSA to recover unpaid wages, along with an equal amount in liquidated damages that courts must award unless the employer proves it acted in good faith and had reasonable grounds to believe it was complying with the law.10Office of the Law Revision Counsel. 29 USC 216 – Penalties Many states have their own wage claim processes through state labor departments, which sometimes resolve faster or offer remedies beyond federal law. Do not wait too long. State and federal statutes of limitations for wage claims typically run two to three years, so acting sooner preserves your options.