Why Did My Paycheck Go Down?

Start with the date. A paycheck that shrank in January has a different cause from one that shrank in July, and a different cause again from one that shrank right after a raise. Work through these in order — the first four cover the large majority of cases.

Tax year 2026 · Updated 2026-08-29 · Guide

1. It is January

The most common cause of all, and it catches people every year. Social Security withholding stops for the year once your wages reach the annual wage base — $184,500 for 2026. If you crossed it in October, your November and December paychecks were 6.2% larger than normal. In January the base resets to zero and 6.2% comes out again.

Nothing went wrong. Your December paycheck was the anomaly, not your January one. The same reset applies to any annual benefit maximum and to state disability and paid-leave premiums with wage caps.

January also brings new benefit elections from open enrolment, a new year of health premiums, and — in most years — new withholding tables. Any of the three can move a paycheck by tens of dollars.

2. You got a raise

A raise never reduces take-home pay through the tax brackets — only the dollars above a threshold are taxed at the higher rate. But two things can make it look that way.

First, withholding annualizes. From the raise onward, payroll withholds as though you had earned the higher salary all year, which slightly over-withholds. Second, percentage-based deductions scale up: a 401(k) set at 6% takes more dollars from a bigger salary, as does a percentage-based ESPP or charitable deduction.

The genuine cliffs are in benefits rather than taxes — premium tax credits, childcare subsidies and income-driven student loan repayment can all step down at specific income levels. The raise calculator shows what a rise is worth after tax.

3. There was a bonus in the previous check

If the check that felt normal contained a bonus, the comparison is misleading. But there is a second effect worth knowing: if the bonus was processed with regular wages under the aggregate method, that period was withheld at a very high annualized rate, and the following normal check simply returns to the correct rate — making the bonus check look better and the next one worse than either really is. The aggregate bonus calculator explains the mechanism.

4. A benefit deduction changed

Open enrolment changes, a new dependent added to your health plan, an FSA election that resets each January, life insurance that reprices on your birthday, or a deduction that was previously being caught up and has now started in full.

Compare the deduction column of the two stubs line by line rather than looking only at the net figure. A $60 difference in a health premium is easy to miss and completely explains a $60 difference in net pay. How to read a pay stub covers the layout.

5. Fewer hours, or a different number of workdays

For hourly workers this is usually obvious. For salaried workers it can be hidden: unpaid leave, a partial pay period at the start or end of employment, or a leave of absence where benefit deductions continued but pay did not.

Bi-weekly and weekly schedules also produce months with an extra paycheck, which makes the surrounding months feel thin by comparison even though nothing changed.

6. Your W-4 changed — or someone else's did

A new W-4 you filed, a life event that prompted HR to reset your form, or a spouse's job change that should have prompted one. Also check whether a dependent aged out: the $2,200 credit for a qualifying child ends the year they turn 17, dropping to $500.

If your employer received an IRS lock-in letter, they are required to withhold at the rate the letter specifies regardless of what you file. You would have been notified.

7. You crossed $200,000 in wages

The Additional Medicare Tax of 0.9% starts when your wages with an employer exceed $200,000 in the calendar year. It is employee-only with no employer match, and it applies regardless of your filing status. Crossing that line mid-year reduces every subsequent paycheck by 0.9% of gross.

8. A state or local rate changed

Several states changed rates for 2026, some mid-year. Utah cut its rate on 1 June and West Virginia on 12 June, both with retroactive effect. Minnesota launched a brand new 0.44% paid-leave premium on 1 January. Washington raised its paid-leave premium by nearly a quarter. Indiana counties reset rates in January based on where you lived on the first of the month.

Your state page lists what changed for 2026.

9 to 12. The less common causes

A garnishment or levy started. These arrive without warning from your perspective and appear as a post-tax deduction. The garnishment calculator covers the legal limits.

A 401(k) auto-escalation. Many plans raise your contribution rate by one point each year automatically unless you opt out.

A payroll correction. If you were overpaid previously, the recovery usually appears as a negative adjustment on a later check.

Your employer changed payroll providers. Migration frequently resets W-4 data to defaults, and the default is single with no adjustments — the most conservative setting there is.

How to diagnose it in five minutes

Put the two stubs side by side and compare in this order: gross pay, then each pre-tax deduction, then each tax line, then each post-tax deduction. The difference will be in exactly one of those columns, and identifying which one tells you the cause.

If it is in the tax lines and gross pay is unchanged, run both scenarios through the calculator at the top of this page. If the calculator agrees with the new figure, the withholding is correct and something about your W-4 or your year-to-date position changed. If it disagrees, take both stubs to payroll.

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