What Gets Deducted From Your Paycheck

Your paycheck has money taken out for federal income tax, Social Security tax, and Medicare tax. These three deductions are calculated differently, and the amounts depend on what you earn, where you live, and the information you gave your employer on your W-4 form. Understanding how each one works helps you know why your take-home pay is smaller than your gross pay.

Federal income tax is withheld based on your W-4 answers and your pay frequency. Social Security tax is a flat 6.2% of your wages up to a yearly cap (the cap changes each year). Medicare tax is 2.9% of all your wages with no upper limit. Some states and cities also withhold income tax, which varies by location.

Key Takeaways

  • Federal income tax withholding depends on your W-4 form, which tells your employer how many allowances you claim and whether you have multiple jobs or a working spouse.
  • Social Security tax is always 6.2% of your gross pay, but only up to a yearly wage cap that changes annually.
  • Medicare tax is 2.9% of all your wages with no cap, and an additional 0.9% applies to wages over a threshold that depends on your filing status.
  • Your employer calculates these deductions on each paycheck using your gross pay, tax tables, and the W-4 information you provided.
  • State and local income tax deductions vary by where you work and live, so you may see additional withholding beyond federal taxes.

How Federal Income Tax Withholding Is Calculated

Your employer uses the W-4 form you completed to determine how much federal income tax to withhold from each paycheck. The W-4 asks for your filing status (single, married, head of household), the number of dependents you claim, and whether you have other income or a spouse who works. Each answer adjusts the amount withheld.

The IRS publishes tax withholding tables that your employer's payroll system uses to look up the correct amount based on your pay frequency, gross pay, and W-4 entries. If you claim zero allowances, more tax is withheld. If you claim more allowances, less is withheld. The goal is to have roughly the right amount withheld so you do not owe a large bill or get a huge refund when you file your tax return.

If you change jobs, get married, have a child, or your income changes significantly, you can fill out a new W-4 and submit it to your employer. The new withholding takes effect on your next paycheck.

How Social Security Tax Is Calculated

Social Security tax is straightforward: it is 6.2% of your gross pay. Your employer withholds this amount from every paycheck, but only on wages up to an annual cap. The cap increases each year — for example, in 2024 the cap was $168,600, meaning once you earn that much in a calendar year, no more Social Security tax is withheld for the rest of that year.

To calculate your Social Security tax on a single paycheck, multiply your gross pay by 0.062. If you earn $1,500 gross in a week, your Social Security tax is $1,500 × 0.062 = $93. Your employer also pays an equal 6.2% on your behalf, but that does not come out of your paycheck.

If you work for multiple employers in the same year, each one withholds 6.2% up to the cap. You might overpay if your combined earnings exceed the cap, but you can claim a credit when you file your tax return to recover the overpayment.

How Medicare Tax Is Calculated

Medicare tax has two parts. The first part is 2.9% of all your wages with no upper limit — this applies to every dollar you earn. The second part is an additional 0.9% on wages above a threshold. The threshold depends on your filing status: $200,000 for single filers, $250,000 for married filing jointly, and $125,000 for married filing separately.

To calculate the base Medicare tax, multiply your gross pay by 0.029. If you earn $2,000 gross in a week, your Medicare tax is $2,000 × 0.029 = $58. Your employer also pays an equal 2.9% on your behalf.

The additional 0.9% Medicare tax is withheld only if your year-to-date wages exceed your threshold. Your payroll system tracks this and begins withholding the extra 0.9% once you cross the threshold. Like Social Security, your employer also pays an equal 2.9% Medicare tax, but the additional 0.9% is your responsibility alone.

State and Local Income Tax Deductions

Many states and some cities withhold income tax in addition to federal taxes. The calculation varies by location — some states use a flat percentage, while others use tax brackets similar to federal income tax. A few states (Alaska, Florida, Nevada, South Dakota, Tennessee, Texas, Washington, and Wyoming) do not have state income tax, so no state withholding occurs.

Your employer needs to know your state and local tax residency to withhold correctly. If you work in one state but live in another, you may owe tax to both, or one state may give you a credit for taxes paid to the other. This is especially common for people who work across state lines.

If you move during the year or change jobs in a different state, tell your employer so they can adjust your withholding. Some states also allow you to claim dependents or file a state W-4 equivalent to adjust your withholding.

What Happens If Your Withholding Is Wrong

If too much tax is withheld throughout the year, you will receive a refund when you file your tax return. If too little is withheld, you will owe money. Neither outcome is ideal — a large refund means you gave the government an interest-free loan, and owing money means you may owe penalties if the underpayment was significant.

You can adjust your withholding by submitting a new W-4 to your employer at any time. If you expect to owe money, increasing your withholding now reduces what you will owe later. If you expect a large refund, decreasing your withholding lets you take home more pay each week.

Self-employed people and those with investment income may need to make quarterly estimated tax payments instead of relying on paycheck withholding. This is different from the withholding system and requires separate calculations and payments to the IRS.

Using a Paycheck Calculator to Check Your Deductions

Many online paycheck calculators let you enter your gross pay, state, filing status, and W-4 information to see what your deductions should be. These tools use the same IRS tax tables that payroll systems use, so they can give you a rough estimate of your take-home pay.

The IRS also offers the Tax Withholding Estimator on its website, which helps you determine whether your current withholding is on track. You answer questions about your income, filing status, and dependents, and it tells you whether you should adjust your W-4.

Keep in mind that calculators are estimates — your actual paycheck may differ slightly because of rounding, timing of pay periods, or other factors. But they are useful for understanding the general breakdown of your deductions and for deciding whether to change your W-4.

Frequently Asked Questions

Why is my take-home pay so much less than my gross pay?

Federal income tax, Social Security tax (6.2%), and Medicare tax (2.9%) are withheld from every paycheck. Together these can total 15% to 25% or more of your gross pay, depending on your income and W-4 choices. State and local taxes add more. Your employer also withholds for any benefits you enrolled in, like health insurance or retirement contributions.

Can I avoid paying Social Security and Medicare tax?

No. These taxes are mandatory for all employees and are withheld from every paycheck. The only exception is certain religious groups that have been granted exemptions by the IRS, and some government employees hired before specific dates. Most workers cannot avoid these deductions.

What if I have two jobs — do I pay Social Security tax twice?

Yes, each employer withholds 6.2% Social Security tax up to the annual cap. If your combined earnings from both jobs exceed the cap, you will overpay. When you file your tax return, you can claim a credit for the overpayment and the IRS will refund it to you.

Does my W-4 affect Social Security and Medicare tax?

No. Your W-4 only controls federal income tax withholding. Social Security and Medicare taxes are calculated the same way for everyone based on your gross pay, regardless of what you claim on your W-4.

How often does the Social Security wage cap change?

The Social Security wage cap changes once per year, usually in October or November, based on average wage growth. You can find the current year's cap on the Social Security Administration website or ask your payroll department.