Why Is My Paycheck Different Every Month?

You have a salary, so your paycheck should be the same every time, right? Not always. Here are the most common reasons your net pay fluctuates.

1. Tax Withholding Adjustments

If you updated your W-4 (after getting married, having a child, or changing deductions), your federal withholding changes. Your employer recalculates based on the new form.

2. Benefits Open Enrollment

If you changed your health insurance plan, added a dependent, or adjusted your 401(k) contribution during open enrollment, your deductions changed — and so did your net pay.

3. Bonus or Commission Pay

Bonuses are often taxed at a flat 22% federal rate (supplemental wage withholding), which is different from your normal bracket. This can make bonus paychecks look smaller or larger than expected.

4. Overtime or Extra Hours

If you're hourly or non-exempt, working more hours means more gross pay — but it can also push you into a higher tax bracket for that period, changing the withholding rate.

5. Pay Period Quirks

Biweekly pay gives you 26 paychecks a year — but most months have two, and two months a year have three. Those "extra" paycheck months can feel like a bonus. Semimonthly pay (24 checks) is more even.

6. Year-End Limits

Social Security tax stops once you hit the annual wage cap ($168,600 in 2025). If you earn above that, your paychecks get larger late in the year when FICA stops withholding.