process

Why your paycheck changed this month: the diagnostic flowchart

7 min read · published 2026-05-05 · updated 2026-05-05

A diagnostic flowchart you can run in five minutes to identify the most likely cause of a paycheck change. Walk it top to bottom and the answer is almost always one of nine items.

Educational only — not advice. PayslipIQ USA provides educational guidance only. It is not legal, tax, accounting, payroll, employment, credit, financial, or consumer reporting advice. Results are estimates based on the information you enter or upload and may be incomplete, outdated, or inaccurate. PayslipIQ USA does not verify income, certify payroll accuracy, determine legal violations, or confirm that money is owed. PayslipIQ is independent and not affiliated with the IRS, SSA, U.S. Department of Labor, any state tax agency, employer, or payroll provider. Always confirm with your employer, payroll department, the IRS, your state labor or revenue agency, a CPA, attorney, or another qualified professional before acting.Figures reflect tax year 2025. Last verified 2025-04-01. Rules and limits may change.

Step 1 — gross pay changed?

If gross pay is different from the previous period, the cause is in earnings: hours, rate, overtime, bonus, commission, RSU vesting, or one-time pay item.

Step 2 — gross pay same but deductions changed?

Look at federal withholding. If federal withholding moved meaningfully, check (a) did you submit a new W-4 in the last 30 days, (b) did year-to-date wages cross a bracket boundary, or (c) was a supplemental wage paid this period.

Step 3 — Social Security dropped to $0?

You crossed the $176,100 wage base. Take-home will be about 6.2% of pre-tax wages higher for the rest of the year. The line returns to 6.2% on January 1.

Step 4 — Additional Medicare line appeared?

YTD wages crossed $200,000. Additional Medicare 0.9% applies to the wages over $200k for the rest of the year. Your actual annual liability depends on filing status.

Step 5 — state tax changed?

New state W-4? Address change in payroll? Work-state change? State tax law change for the new year? Or year-to-date crossed a state bracket?

Step 6 — local tax appeared or changed?

Did your work or home address change to a city/county that levies local tax? OH, PA, NY, MI, KY, MO, MD, IN, CO, OR are common.

Step 7 — benefit deduction changed?

Mid-year health/dental/vision premium increase? Open enrollment took effect this period? New benefit added (HSA, FSA, supplemental insurance)?

Step 8 — retirement deduction changed?

Did you adjust your 401(k) percentage? Did a catch-up contribution kick in (age 50+)? Did the bonus include a 401(k) deferral?

Step 9 — new garnishment or court order?

A new wage garnishment, child-support income withholding order, or IRS levy can appear without warning. Ask payroll for the order copy.

If none of the above

Run the Pay Stub Checker against both stubs side by side. Use the Ask Payroll Generator to send a polite question with the specific gap you cannot explain. PayslipIQ flags differences that exceed normal thresholds — those flags are questions worth asking, not confirmed errors.