Why is my January paycheck different?
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A first paycheck of the year is often smaller even with no change in pay: Social Security tax starts again, your 401(k) or health insurance takes more, or the tax tables change. Put in your pay to see which hit you, biggest first. Nothing is uploaded.
For general guidance only, not tax advice. We estimate withholding from your yearly pay the way payroll software does for a standard 2020-or-later W-4, with no extra withholding and no dependents. Your employer's numbers can be off from ours by a few dollars. Check your own pay stub, and ask your payroll team about anything big.
The five reasons a January paycheck changes
- Social Security tax starts again. Social Security tax is 6.2% of your pay, but only up to a yearly limit. In 2026 the limit is $184,500. If you earned more than that at one job, the tax stopped partway through the year, and your last paychecks were bigger. On January 1 the count starts from $0, so the 6.2% comes back on your first 2027 paycheck. The 2027 limit is $192,300. The extra 0.9% Medicare tax on pay over $200,000 restarts its count on January 1 too, so it drops off your January paycheck. State disability, paid-leave and unemployment deductions with a yearly limit (in New Jersey and New York, for example) restart the same way and come back.
- You save more in your 401(k). Many people raise their savings rate for the new year. More saving means less take-home pay, but less of it than you might think, because the 401(k) money is not taxed now.
- Your health insurance costs more. Most employers set new prices on January 1. A higher premium takes more out of each paycheck, though it also lowers your taxes a little.
- The federal tax tables change. Each year the IRS raises the tax brackets and the standard deduction (the part of your income that is not taxed) for inflation. That usually means a little less federal tax in January.
- Your state's tax tables change. Some states change rates or deductions on January 1.
Your gross pay itself does not change in January unless you got a raise. If it did, that is a sixth reason, and you can see it by putting your new salary in the calculator.
A worked example
Sam earns $200,000 a year in Texas, is paid every two weeks and files single. Sam saves 6% in a 401(k) in both years. Sam's health insurance goes from $150 to $165 a paycheck in 2027. Sam's January paycheck is about $464.07 smaller than December's.
- Pay per paycheck: $200,000 ÷ 26 = $7,692.31. The 401(k) is 6% of that, $461.54.
- Social Security: before the last December paycheck Sam had earned 25 paychecks of $7,692.31 minus the $150.00 health premium, which is $188,557.75. That is past the $184,500 limit, so December has $0 of Social Security tax. In January the count restarts at $0: 6.2% × ($7,692.31 − $165.00) = $466.69.
- Medicare: 1.45% of pay after the health premium, with no limit: $109.36 in December, $109.15 in January. Sam stays under $200,000 of Medicare pay at this job, so the extra 0.9% never starts.
- Federal income tax: taxed yearly pay is $200,000 minus the 401(k) (26 × $461.54 = $12,000.04), the health premium (26 × $150 or 26 × $165) and the standard deduction. In 2026 that is $167,999.96 with a $16,100 standard deduction; in 2027 it is $167,109.96 with $16,600 (projected). Run through each year's brackets and split across 26 paychecks, that is $1,266.08 in December and $1,248.67 in January.
| Line | December 2026 | January 2027 | Change |
|---|---|---|---|
| Pay before anything comes out | $7,692.31 | $7,692.31 | $0.00 |
| 401(k) savings (6%) | $461.54 | $461.54 | $0.00 |
| Health insurance | $150.00 | $165.00 | +$15.00 |
| Federal income tax | $1,266.08 | $1,248.67 | -$17.41 |
| Social Security tax | $0.00 | $466.69 | +$466.69 |
| Medicare tax | $109.36 | $109.15 | -$0.21 |
| Take-home pay | $5,705.33 | $5,241.26 | -$464.07 |
What changed, biggest first:
- Social Security tax starts again: -$466.69. You passed the $184,500 Social Security limit before December, so your December paycheck had no Social Security tax. On January 1 the count starts again at $0, so the 6.2% comes back: $466.69 on your first 2027 paycheck. The 2027 limit is $192,300.
- New federal tax tables: +$13.81. The 2027 tax brackets and standard deduction are higher, to keep up with prices, so federal income tax on each paycheck is $13.81 lower than the 2026 tables would take. This is an estimate: the IRS has not published the official 2027 tables yet, so we use projected ones.
- Your health insurance costs more: -$11.19. It goes from $150.00 to $165.00 a paycheck. It comes out before tax, so your taxes go down by $3.81.
Sam's January paycheck stays at this size until Sam passes $192,300 again, late in 2027. Then the Social Security tax stops and the paychecks grow again.
Common questions
Why is my first paycheck of the year smaller? Usually for one of five reasons. Social Security tax starts again if you earned more than its $184,500 limit in 2026. You may save more in your 401(k), or your health insurance may cost more. And the federal and state tax tables change on January 1. The calculator above shows which ones apply to you.
Why did Social Security tax come back in January? Social Security tax is 6.2% of your pay, but only up to a yearly limit at each job: $184,500 in 2026 and $192,300 in 2027. Once you pass it, the tax stops for the rest of the year. On January 1 the count starts again at $0, so the tax comes back.
Does Medicare tax stop too? No. Medicare tax (1.45%) has no yearly limit and comes out of every paycheck. Only the extra 0.9% Medicare tax, on pay over $200,000 at one job, starts counting again in January.
Will my paycheck stay smaller all year? It depends on the reason. A higher 401(k) rate or health premium lasts all year. Social Security tax lasts until you pass the $192,300 limit again, which only happens if you earn more than that at one job.
Are the 2027 tax brackets final? Not yet. The IRS has not published the official 2027 tax tables. This page uses the projections published by tax research firms, and switches to the official figures when the IRS releases them.
Why is my January paycheck bigger instead? The new federal tax tables usually take a little less tax. And if you lowered your 401(k) savings or your health insurance got cheaper, take-home pay goes up.
Where the 2027 numbers come from
The IRS has not published its official 2027 tax tables yet. Until it does, January's federal tax uses the 2027 projections published by Wolters Kluwer, Thomson Reuters and Bloomberg Tax. They agree on every tax bracket. For head of household filers their standard deduction ranges from $24,900 to $24,950; we use the lowest, $24,900, so January is never shown better than it may turn out. This page switches to the official figures as soon as the IRS publishes them.
The 2027 Social Security limit of $192,300 is official: it is on Social Security's 2027 fact sheet.
State income tax for January uses each state's 2026 tables, until 2027 state tables are in our data. The exceptions, already set in state law, so we use them: Montana's 2027 income tax brackets (Montana Department of Revenue: HB 337 income tax changes), New York's 2027 income tax rates (N.Y. Tax Law § 601), Virginia's 2027 standard deduction (Va. Code § 58.1-322.03), North Carolina's 2027 income tax rate (N.C. Session Law 2026-41 (Senate Bill 257)), Indiana's 2027 income tax rate (Indiana Department of Revenue: Rates, Fees & Penalties), Mississippi's 2027 income tax rate (Mississippi H.B. 1 (2025), Build Up Mississippi Act) and Nebraska's 2027 income tax rate (Office of Governor Jim Pillen: income tax cuts effective in January).
| Figure | Status | Where it comes from |
|---|---|---|
| Social Security limit: $192,300 | Official | Social Security, 2027 Cost-of-Living Adjustment (COLA) Fact Sheet |
| Federal standard deduction: $16,600 single, $33,200 married, $24,900 head of household | Estimate | Projections by Wolters Kluwer, Thomson Reuters and Bloomberg Tax |
| Federal tax brackets | Estimate | The same projections. See projected 2027 tax brackets. |
| Social Security 6.2%, Medicare 1.45%, extra Medicare 0.9% over $200,000 | Fixed in law | These rates and the $200,000 line do not change with inflation. |
| State income tax | 2026 tables | Each state's 2026 tables, except Montana, New York, Virginia, North Carolina, Indiana, Mississippi and Nebraska. |
We do not model the yearly 401(k) limit, catch-up savings, dependents, extra withholding you asked for on your W-4, or local taxes. Those can move a paycheck too.
Related
- Social Security wage base calculator: the 2026 paycheck your Social Security tax stops on.
- Projected 2027 federal tax brackets: the projections behind January's federal tax.
- Paycheck calculator for your state: your take-home pay on any paycheck.
- 401(k) calculator: what a higher savings rate adds up to.