What comes out of your paycheck and why
Your employer withholds taxes from each paycheck based on information you provide on your W-4 form — the document you fill out when you start a job. The amount withheld covers federal income tax, Social Security tax (6.2% of your gross pay), and Medicare tax (1.45% of your gross pay). Some states and cities also withhold income tax. The goal is to have enough withheld over the year so you do not owe a large amount when you file your tax return in April.
The federal income tax withheld is not a flat percentage — it depends on your filing status, the number of dependents you claim, and your expected annual income. This is why two people earning the same weekly wage can have different amounts withheld.
Key Takeaways
- Social Security and Medicare taxes are fixed percentages (6.2% and 1.45%) that come out of every paycheck, with no upper income limit for Medicare.
- Federal income tax withholding is calculated using your W-4 form, your pay frequency, and IRS withholding tables that change each year.
- You can estimate your annual withholding by multiplying your per-paycheck amount by the number of pay periods in a year (26 for biweekly, 24 for semimonthly, 52 for weekly).
- If too much or too little is being withheld, you can adjust your W-4 at any time — you do not have to wait until next year.
- Your pay stub shows the gross amount, each deduction, and your net (take-home) pay, so you can verify the math yourself.
How to read your pay stub
Your pay stub is the document your employer gives you with each paycheck. It shows your gross pay (the amount before any deductions), each tax and deduction withheld, and your net pay (what you actually receive). The stub also shows year-to-date totals, so you can track how much you have paid in taxes so far this year.
Look for these line items: Federal Income Tax Withheld, Social Security Tax (labeled OASDI or Social Security), Medicare Tax, and any state or local income tax. If you have a 401(k), health insurance premium, or other deductions, those appear here too. The math is straightforward: Gross Pay minus all deductions equals Net Pay.
Calculating Social Security and Medicare withholding
These two taxes are the easiest to calculate because they are fixed percentages with no variation based on your filing status or dependents. Social Security tax is 6.2% of your gross pay, up to a wage cap that changes each year. Medicare tax is 1.45% of your gross pay with no upper limit. If you earn over $200,000 (or $250,000 if married filing jointly), an additional 0.9% Medicare tax applies to income above that threshold.
To calculate these on a single paycheck: multiply your gross pay by 0.062 for Social Security, and by 0.0145 for Medicare. For example, if you earn $1,500 gross on a paycheck, Social Security withholding is $1,500 × 0.062 = $93, and Medicare is $1,500 × 0.0145 = $21.75. Your pay stub should show these exact amounts.
Understanding federal income tax withholding
Federal income tax withholding is more complex because it depends on your W-4 form and IRS withholding tables. When you fill out your W-4, you tell your employer your filing status (single, married, head of household), the number of dependents you claim, and whether you have other income or jobs. Your employer uses this information plus IRS Publication 15-T (the withholding tables) to calculate how much to withhold from each paycheck.
The IRS updates these tables each year, which is why your withholding may change even if your W-4 stays the same. The tables account for your pay frequency — weekly, biweekly, semimonthly, or monthly — because the same annual income spread across 26 paychecks (biweekly) looks different to the tax tables than the same income spread across 52 paychecks (weekly).
You cannot easily calculate federal withholding by hand without the actual IRS tables, but you can estimate your annual federal tax by multiplying your per-paycheck withholding by the number of pay periods in a year. If your pay stub shows $150 federal income tax withheld and you are paid biweekly (26 times per year), your estimated annual federal withholding is $150 × 26 = $3,900.
Estimating your total annual tax withholding
To see whether your withholding is roughly on track, add up all the taxes withheld from one paycheck and multiply by the number of pay periods in a year. The pay periods are: 52 for weekly, 26 for biweekly, 24 for semimonthly, and 12 for monthly.
For example, if you are paid biweekly and one paycheck shows $150 federal income tax, $93 Social Security, and $21.75 Medicare, your total per-paycheck withholding is $264.75. Multiply by 26: $264.75 × 26 = $6,883.50 in total tax withholding for the year. You can compare this rough estimate to your expected tax liability when you file your return, though the actual amount you owe depends on your deductions and credits.
State and local income tax withholding
If you live in a state with income tax, your employer withholds that as well. The percentage and calculation method vary by state — some use a flat percentage, others use brackets similar to federal tax. A few states (Alaska, Florida, Nevada, South Dakota, Tennessee, Texas, Washington, and Wyoming) have no state income tax. New Hampshire and Tennessee tax only dividend and interest income, not wages.
Some cities also withhold local income tax — this is common in Ohio, Pennsylvania, and parts of other states. Your pay stub will show state and local withholding separately. If you work in one state but live in another, the rules can be complicated; your employer should withhold based on where you work, but you may owe taxes to your home state as well. Check your state's tax authority website for specifics.
When to adjust your W-4
If you notice that too much or too little is being withheld, you can change your W-4 at any time — you do not have to wait until next year. If you are getting a large refund every April, you are having too much withheld; if you owe money, you are having too little withheld. You can also adjust your W-4 if your life changes: marriage, divorce, a second job, a child, or a major change in income.
To adjust, fill out a new W-4 form and give it to your payroll department or HR. The change takes effect on your next paycheck. The IRS provides a W-4 calculator on its website (irs.gov) that walks you through the form and suggests how many allowances to claim based on your situation. This calculator is the most reliable way to get your withholding close to correct.
Frequently Asked Questions
Why is my federal income tax withholding different from my coworker's if we earn the same amount?
Your W-4 form controls federal withholding. If you and your coworker have different filing statuses, different numbers of dependents, or different other income, your withholding will differ even at the same pay rate. You may also have filled out your W-4 at different times, and the IRS updates withholding tables annually.
Can I claim zero allowances to have more withheld?
On the current W-4 form (redesigned in 2020), you do not claim "allowances" anymore. Instead, you enter the number of dependents and other adjustments. If you want more withheld, you can enter an extra amount on line 4(c) of the W-4 form, or you can adjust your filing status or dependent claims downward.
What does "gross pay" mean on my pay stub?
Gross pay is your total earnings before any deductions. It includes your hourly wage or salary, overtime, bonuses, and any other compensation. Taxes and other deductions are subtracted from gross pay to arrive at your net (take-home) pay.
Is the Social Security tax cap the same every year?
No. The Social Security wage base limit changes each year based on inflation. Once your gross pay reaches that limit in a calendar year, no more Social Security tax is withheld for the rest of that year. Medicare tax has no cap and continues on all income. Your pay stub will show when you have hit the Social Security cap.
How do I know if my withholding is correct?
The best check is your tax return. If you owe money or get a large refund, your withholding was off. You can also use the IRS W-4 calculator mid-year to see whether your current withholding will result in a refund or a bill. Aim for withholding close enough that you do not owe more than a few hundred dollars or receive more than a few hundred back.