Why Did My Paycheck Change? Common Reasons Explained

Key takeaways

• First confirm dates, hours, rate, overtime, leave and supplemental pay.
• Gross pay can stay the same while taxable wages change because of pretax benefits or imputed income.
• Federal withholding can change after a W-4 update, a tax-table update or a change in taxable wages.
• Benefit premiums, retirement elections and deduction schedules often change at enrollment or year boundaries.
• A levy, garnishment or payroll correction should have supporting documentation.

1. The pay period or gross earnings changed

Check the period start and end dates, payday, hours and pay rate. Hourly pay can move with scheduled hours, unpaid leave, shift differentials, commissions and tips. A salaried employee can still see a different check when unpaid leave, a bonus or another permitted adjustment is involved.

For covered, nonexempt employees, the Fair Labor Standards Act generally requires overtime pay of at least one and one-half times the regular rate for hours over 40 in a workweek, subject to exemptions and special rules. A biweekly pay period does not ordinarily allow an employer to average a 45-hour week with a 35-hour week. State law may provide additional protections.

2. Taxable wages changed even if gross pay did not

Federal income-tax wages, Social Security wages and Medicare wages can differ. A new qualified pretax health deduction may reduce more than one tax base. A traditional 401(k) deferral generally reduces federal income-tax wages but not FICA wages. Taxable fringe benefits or group-term life insurance can increase a tax base without increasing cash by the same amount.

Compare each taxable-wage line rather than only the deduction amount. If a benefit started midyear, the first affected check may show both the new deduction and a changed tax calculation.

3. Federal or payroll taxes changed

Federal income-tax withholding responds to taxable wages, pay frequency and the Form W-4 on file. A change to filing status, multiple-jobs handling, credits, deductions or Step 4(c) additional withholding can alter net pay. Employers also begin using current-year IRS withholding tables, which can change a January paycheck even when the W-4 is unchanged.

As of this review, IRS Publication 15 lists the 2026 employee Social Security rate as 6.2% on covered wages up to $184,500 and the Medicare rate as 1.45% without a wage-base limit. Once an employee reaches the Social Security wage base with one employer, that employer generally stops the employee Social Security deduction for the rest of the year; it can restart in January. Medicare continues, and the employer begins an additional 0.9% Medicare withholding on wages it pays above $200,000 for the year. Later guidance and specific wage facts can affect treatment.

4. A benefit or retirement deduction changed

Open-enrollment elections often start with a new plan year. Premium rates can change, and deductions can vary if the employer collects benefits on only selected checks. A 401(k) percentage produces a larger dollar deduction when eligible pay rises. Loan repayments, flexible spending accounts, health savings accounts, union dues and commuter benefits can also begin, stop or reach an annual limit.

Separate employee deductions from employer contributions. An employer match displayed on the stub may be informational and should not reduce the deposit. Review the election confirmation and plan document before assuming the payroll line is incorrect.

5. A bonus or other supplemental wage was paid

IRS Publication 15 treats bonuses, commissions, certain overtime payments, severance, back pay and other items as supplemental wages. Depending on how the employer pays and identifies them, federal withholding may be calculated by combining the payment with regular wages or by an allowed supplemental method. For 2026, Publication 15 states that the optional flat rate remains 22% when its conditions are met, with a mandatory 37% rate applying to supplemental wages over $1 million. Withholding is a prepayment, not necessarily the final tax rate on the bonus.

6. A correction, garnishment or levy appeared

Payroll may correct an earlier overpayment, underpayment, missed deduction or time entry. The stub should identify the affected earning or deduction, but abbreviations can be unclear. Employers covered by the FLSA must keep records including additions to and deductions from wages. State pay-statement and deduction-authorization rules may go further.

A court garnishment, child-support order or tax levy can reduce take home pay under separate legal limits and procedures. Ask for the issuing court or agency, order number and calculation. Do not confuse an IRS tax levy with ordinary federal income-tax withholding.

Worked comparison

The exact tax change cannot be inferred from this example because W-4 and state facts are omitted. Its purpose is to reconcile the $125 net increase instead of attributing it vaguely to “taxes.”

Where this comes from

• IRS Publication 15 (2026): employment and supplemental wage taxes (opens in a new tab)
• IRS Publication 15-T (2026): federal withholding methods (opens in a new tab)
• U.S. Department of Labor Fact Sheet 23: overtime (opens in a new tab)
• U.S. Department of Labor Fact Sheet 21: payroll records (opens in a new tab)