What payroll taxes are and where they come from

Payroll taxes are amounts taken directly from your paycheck by your employer. They fund Social Security, Medicare, and federal and state income tax systems. Your employer is required by law to withhold these amounts and send them to the government on your behalf.

When you start a job, you fill out a W-4 form (or W-4P if you receive a pension). This form tells your employer how much to withhold from each paycheck. The more allowances you claim on the W-4, the less your employer withholds. The fewer allowances you claim, the more gets withheld.

Your employer also pays a matching amount in payroll taxes — you do not see this deducted from your check, but it comes out of the company's budget. This employer portion funds the same Social Security and Medicare systems your withholding does.

Key Takeaways

  • Social Security and Medicare taxes are fixed percentages (6.2% and 1.45% respectively in 2024) that come out of every paycheck up to an annual earnings cap for Social Security.
  • Federal income tax withholding depends on what you claimed on your W-4 form and changes if your life situation changes — marriage, a second job, dependents, or major income shifts.
  • State and local income taxes vary by where you live and work; some states have no income tax, while others withhold 5% to 10% or more.
  • Your pay stub shows gross pay (before taxes), all deductions, and net pay (what you actually receive); comparing these numbers tells you exactly what was withheld and why.
  • If too much or too little is withheld over the year, you will either owe money at tax time or receive a refund when you file your return.

Social Security and Medicare taxes — the fixed percentages

Social Security tax is 6.2% of your wages, up to a cap that changes each year. In 2024, that cap is $168,600 in annual earnings. Once you earn that much in a calendar year, no more Social Security tax is withheld from your remaining paychecks that year. This is called the wage base.

Medicare tax is 1.45% of all your wages with no cap — it keeps coming out no matter how much you earn. If you earn over $200,000 as a single filer (or $250,000 married filing jointly), an additional 0.9% Medicare tax is withheld on the amount above that threshold.

These two taxes together are sometimes called FICA taxes (Federal Insurance Contributions Act). They are the same for every worker at the same income level — there is no variation based on your W-4 choices or personal situation. Your pay stub will show these as separate line items.

Federal income tax withholding — what your W-4 controls

Federal income tax withholding is not a fixed percentage. Instead, your employer uses a withholding table published by the IRS that depends on three things: your filing status (single, married, head of household), how often you are paid (weekly, biweekly, monthly), and what you claimed on your W-4.

On the W-4, you claim allowances or dependents (the form changed in 2020, but both versions use similar logic). Each allowance reduces the amount withheld. If you claim zero allowances, more is withheld. If you claim many allowances, less is withheld. The IRS provides a worksheet on the W-4 itself to help you figure out the right number, or you can use the IRS Withholding Calculator on irs.gov.

You should update your W-4 when your life changes: you get married or divorced, you have a child, you take a second job, your spouse starts working, or your income drops significantly. You can submit a new W-4 to your employer at any time during the year, and the new withholding takes effect on your next paycheck.

State and local income taxes — they vary by location

Nine states have no state income tax at all: Alaska, Florida, Nevada, South Dakota, Tennessee, Texas, Washington, Wyoming, and New Hampshire (which taxes only dividends and interest, not wages). If you live and work in one of these states, you will see no state income tax line on your pay stub.

In the other 41 states, state income tax is withheld from your paycheck. The rate varies widely — from about 1% in some states to over 13% in others. Some states use a flat rate (everyone pays the same percentage), while others use brackets similar to federal tax (higher earners pay a higher percentage). You provide state tax information on a state W-4 form, which works similarly to the federal W-4.

Many cities and counties also impose local income taxes. New York City, Philadelphia, and Columbus, Ohio are examples. If you work in a city with a local tax, it will appear as a separate line on your pay stub. The rate is usually 1% to 3% of gross pay.

Reading your pay stub to see what was withheld

Your pay stub is the document that shows exactly what happened to your paycheck. It lists your gross pay (total earnings before any deductions), each deduction line by line, and your net pay (what you actually receive).

A typical pay stub shows these withholdings in this order: federal income tax, Social Security tax, Medicare tax, state income tax, and local income tax if applicable. It may also show voluntary deductions like health insurance premiums, 401(k) contributions, or union dues — these are not taxes, but they reduce your net pay the same way.

To check if your withholding is correct, add up all the tax withholdings for the year (most employers provide a year-to-date total on each stub) and compare that to what you expect to owe when you file your tax return. If the withholding is much higher than what you owe, you will receive a refund. If it is much lower, you will owe money.

What happens if too much or too little is withheld

Withholding is an estimate. It is based on the assumption that your income will stay the same all year and that your personal situation will not change. If either assumption is wrong, your withholding will be off.

If too much is withheld, you will receive a tax refund when you file your return. The IRS keeps the extra money interest-free until you file. If too little is withheld, you will owe money when you file. You may also owe a penalty if you underpaid by a large amount, though the IRS has safe-harbor rules that protect you if you withheld at least 90% of what you owe or 100% of what you owed the previous year.

The most common reason for incorrect withholding is a major life change — a second job, a spouse who starts working, a child born, or a job loss mid-year. If you notice your withholding is off partway through the year, submit a new W-4 to your employer. You can adjust your withholding as many times as you need.

Self-employment taxes if you are a contractor or freelancer

If you are self-employed — a contractor, freelancer, or small business owner — you do not have an employer to withhold taxes for you. Instead, you pay self-employment tax directly to the IRS, usually quarterly.

Self-employment tax covers both the employee and employer portions of Social Security and Medicare. That means you pay 15.3% (12.4% Social Security plus 2.9% Medicare) on your net self-employment income, not the 7.65% a regular employee pays. You can deduct half of this amount when you file your return, which reduces your taxable income.

You also owe federal income tax on your self-employment income. You estimate this amount and pay it quarterly using Form 1040-ES. If you live in a state with income tax, you owe state estimated tax as well. Missing these quarterly payments can result in penalties, even if you end up overpaying for the year.

Frequently Asked Questions

Why does my paycheck vary if I get paid the same amount each week?

Payroll taxes are calculated on each individual paycheck, not on your annual salary. If you are paid biweekly, your employer divides your annual salary by 26 to get your gross pay per check. However, Social Security tax has an annual cap — once you hit it mid-year, that tax stops, so your net pay increases for the rest of the year. Bonus checks or overtime also change the gross amount, which changes all the tax withholdings.

Can I claim zero allowances on my W-4 to get a bigger refund?

You can, but it is not a good strategy. Claiming zero allowances means more money is withheld from every paycheck, which reduces your take-home pay throughout the year. You will receive the extra money back as a refund, but only after you file your return — sometimes months later. It is better to adjust your W-4 so your withholding matches what you actually owe, so you keep more money in your pocket each week.

What if I work in one state but live in another?

You typically owe income tax to the state where you work, not where you live. However, some states have reciprocal agreements that change this rule. You should file a state W-4 with the state where you work. If you end up owing tax to both states, you may be able to claim a credit on one return for taxes paid to the other — check your state's tax agency website for details.

Do I have to pay taxes on tips?

Yes. Tips are income and are subject to federal, state, and local income tax, as well as Social Security and Medicare tax. Your employer is required to withhold taxes on tips you report. If you receive cash tips that are not reported to your employer, you are still legally required to report them on your tax return and pay tax on them.

What is the difference between a W-4 and a 1099?

A W-4 is a form you fill out when you are hired as an employee — it tells your employer how much tax to withhold. A 1099 is a form your employer or client sends you at the end of the year showing how much they paid you. If you receive a 1099, you are self-employed and responsible for paying your own taxes; no withholding happens automatically.