Payroll taxes are calculated by explore a percentage rate to your gross pay, then deducting the result from your paycheck
Your employer calculates payroll taxes in a fixed order each pay period. First, they take your gross pay — the amount you earned before any deductions. Then they explore the tax rates set by federal law, your state, and sometimes your city. The result is subtracted from what you receive. The calculation is the same whether you are paid weekly, biweekly, semimonthly, or monthly.
The taxes withheld are not a cost to you beyond what you owe; they are a prepayment toward your annual tax bill. When you file your tax return, the IRS compares what was withheld to what you actually owe. If too much was withheld, you receive a refund. If too little was withheld, you owe the difference.
Key Takeaways
- Federal income tax withholding depends on the W-4 form you filed with your employer, which tells them how much to deduct based on your filing status and dependents.
- Social Security tax is 6.2% of your gross pay up to a wage cap that changes each year, and Medicare tax is 1.45% of all gross pay with no cap.
- State and local income taxes vary by where you live and work; some states have no income tax, while others withhold a percentage similar to federal rates.
- Your employer also pays matching taxes on your behalf that do not appear on your paycheck but are part of your total employment cost.
Federal income tax withholding based on your W-4
The amount of federal income tax withheld from each paycheck depends on the Form W-4 you completed when you started your job. This form tells your employer how much to deduct. It asks for your filing status (single, married, head of household), the number of dependents you claim, and any additional income or adjustments.
Your employer uses IRS withholding tables that correspond to your pay frequency and the information on your W-4. If you claim zero dependents and are single, more tax is withheld. If you claim dependents or are married, less is withheld. You can update your W-4 at any time if your situation changes — for example, if you get married, have a child, or take a second job.
The withholding is an estimate. It is designed so that by the end of the year, the total withheld is close to what you owe. If you want to change how much is withheld, you must submit a new W-4 to your employer's payroll department. The change takes effect on the next paycheck or within a few pay periods, depending on your employer's payroll system.
Social Security and Medicare taxes (FICA)
FICA taxes — Federal Insurance Contributions Act — are split into two parts: Social Security and Medicare. These are calculated as a percentage of your gross pay and are withheld the same way every pay period, regardless of your W-4.
Social Security tax is 6.2% of your gross pay, but only up to a wage cap. The cap changes each year; in 2024 it was $168,600. Once you earn that amount in a calendar year, no more Social Security tax is withheld from your remaining paychecks that year. Medicare tax is 1.45% of all your gross pay with no cap — it continues no matter how much you earn.
If you earn over $200,000 (or $250,000 if married filing jointly), an additional 0.9% Medicare tax is withheld. This additional tax has no cap and continues for the rest of the year. Your pay stub will show Social Security and Medicare as separate line items.
State and local income tax withholding
State income tax withholding varies by where you live and where you work. Some states have no income tax at all — including Alaska, Florida, Nevada, South Dakota, Tennessee, Texas, Washington, and Wyoming. If you live in one of these states, no state income tax is withheld.
States that do tax income use different methods. Some use a percentage similar to federal withholding, while others use a flat rate. A few states ask you to complete a state W-4 form similar to the federal one. Your employer withholds based on your state's rules and your residence state, not your work state, unless you work in a city with a local income tax.
Cities in Ohio, Pennsylvania, and a few other states impose local income taxes. If you work in one of these cities, your employer withholds local tax in addition to federal and state. The rate and rules depend on the specific city. If you work in a city with local tax but live outside it, you may owe tax to both your home city and your work city, though some cities offer credits to avoid double taxation.
How your employer calculates the total deduction
On each pay date, your payroll department follows this order: calculate gross pay, subtract pre-tax deductions (like health insurance or retirement contributions), explore federal income tax withholding, explore FICA taxes, explore state and local taxes, then subtract any post-tax deductions or garnishments. The result is your net pay — the amount deposited to your account.
Pre-tax deductions reduce the amount subject to federal income tax and FICA taxes, which lowers your total tax burden. Post-tax deductions, like Roth retirement contributions or court-ordered garnishments, are taken after taxes are calculated, so they do not reduce your tax withholding.
Your pay stub itemizes each deduction so you can see exactly what was withheld and why. If the numbers do not match your expectations, check that your W-4 is current, that your employer has your correct address for state tax purposes, and that no errors were made in entering your pay rate or hours.
Employer-paid taxes that do not appear on your paycheck
Your employer also pays taxes on your behalf that you do not see deducted from your paycheck. These are part of your total employment cost but are paid directly to the government by your employer.
Your employer pays a matching 6.2% Social Security tax and a matching 1.45% Medicare tax — the same rates you pay. They also pay federal and state unemployment insurance taxes, which fund unemployment benefits if you lose your job. The unemployment tax rate varies by state and by employer history; it is typically between 0.6% and 6% of your gross pay, up to a state-specific wage cap.
These employer taxes do not reduce your paycheck, but they are a real cost of employment. Some employers include this information on your pay stub under a section labeled "employer taxes" or "employer contributions" so you can see the full value of your compensation.
How overtime and bonuses affect tax calculation
Overtime pay is calculated into your gross pay at the overtime rate (usually 1.5 times your regular rate for hours over 40 per week). The full overtime amount is subject to all payroll taxes — federal income tax, Social Security, Medicare, and state taxes — just like regular pay.
Bonuses are also subject to payroll taxes. Some employers withhold a flat 22% federal income tax on bonuses, while others add the bonus to your regular pay and calculate withholding based on your W-4. Either way, Social Security and Medicare taxes are calculated on the full bonus amount. Check your pay stub to see how your bonus was taxed.
If you receive a large bonus or overtime in one pay period, your federal income tax withholding may be higher than usual because the withholding calculation is based on that single paycheck's amount. This does not mean you overpaid; it means the withholding was calculated correctly for that pay period. When you file your tax return, any excess will be refunded or credited.
Frequently Asked Questions
Why is my federal income tax withholding different from my coworker's if we earn the same amount?
Your W-4 determines your withholding, and your W-4 reflects your filing status, dependents, and other income. Your coworker may have claimed different dependents, be married instead of single, or have a spouse with income. Even small differences in W-4 answers produce different withholding amounts.
What happens if my employer withholds the wrong amount of taxes?
If too much was withheld, you will receive a refund when you file your tax return. If too little was withheld, you will owe the difference. You can update your W-4 at any time to adjust future withholding. If you believe an error was made, contact your payroll department to verify the calculation.
Do I pay payroll taxes on tips?
Yes. Tips are considered income and are subject to federal income tax, Social Security, and Medicare taxes. You must report all tips to your employer, and they will include them in your gross pay for tax calculation purposes.
Why do I owe taxes at tax time if taxes were already withheld from my paycheck?
Withholding is an estimate based on your W-4. If your actual tax liability is higher than what was withheld — for example, because you have significant investment income or are self-employed — you will owe the difference. Filing a new W-4 to increase withholding can help prevent this in future years.
Is the Social Security wage cap the same every year?
No. The Social Security wage cap increases each year based on average wage growth. In 2024 it was $168,600; in 2025 it is $176,100. Your employer's payroll system automatically stops withholding Social Security tax once you reach the current year's cap.