What determines your paycheck deductions

The amount of tax taken from your paycheck depends on four things: your gross pay, your filing status, the number of dependents you claim, and your state of residence. Federal income tax is the largest deduction for most people, but you will also see Social Security tax (6.2 percent of gross pay) and Medicare tax (1.45 percent of gross pay) on every paycheck. These three come out automatically before you see your money.

Your employer uses a form called the W-4 to calculate federal withholding. When you start a job, you fill out a W-4 and tell your employer whether you are single, married, have dependents, or have other income. The more dependents or other income you claim, the less federal tax your employer withholds. If you claim zero dependents and are single, more tax comes out. The goal is to withhold roughly what you will owe at tax time, though most people end up with a refund because they over-withhold.

Some states also take income tax from your paycheck. Nine states have no 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 in any other state, your employer will withhold state income tax based on a state W-4 form you fill out, which works similarly to the federal version.

Key Takeaways

  • Federal income tax, Social Security tax, and Medicare tax all come out of every paycheck, with the federal amount depending on what you claimed on your W-4 form.
  • Your W-4 filing status, number of dependents, and other income determine how much federal tax is withheld, and you can change it anytime by submitting a new W-4 to your employer.
  • Nine states have no income tax; all others withhold state income tax based on a state W-4 form you complete when hired.
  • Social Security and Medicare taxes are fixed percentages (6.2 percent and 1.45 percent respectively) and do not change based on your W-4 answers.
  • Most people over-withhold and receive a refund at tax time, but you can adjust your W-4 to take home more money each paycheck if you prefer.

How federal income tax withholding is calculated

Your employer uses IRS tables and your W-4 answers to figure out federal withholding. The IRS publishes different tables for weekly, biweekly, semimonthly, and monthly pay periods. Your employer looks up your gross pay and filing status in the correct table, then subtracts the standard deduction amount for your status. What remains is taxed at the federal rates for that year.

The federal tax brackets for 2024 range from 10 percent on the first portion of income up to 37 percent on income above roughly $578,000 (for single filers). Your paycheck withholding does not use the full year's brackets—it estimates based on your current pay period. If you earn $2,000 biweekly, your employer assumes you will earn roughly $52,000 per year and withholds accordingly. If you earn a bonus or get a raise mid-year, the withholding adjusts to the new amount.

You can see the exact calculation on your pay stub. Look for "Federal Income Tax Withheld" or "FIT." This is the amount your employer sent to the IRS on your behalf. At the end of the year, you will receive a W-2 form showing your total gross pay and total federal tax withheld. When you file your tax return, you compare what you owed to what was withheld. If more was withheld than you owed, you get a refund. If less was withheld, you owe the difference.

Adjusting your W-4 to change withholding

If you want more money in each paycheck, you can reduce your federal withholding by submitting a new W-4 to your employer's payroll department. You might do this if you are married and both spouses work, if you have significant non-wage income, or if you consistently get a large refund. Claiming more dependents or adjusting the "other income" section will lower your withholding.

The opposite is also true: if you want to withhold more (to avoid owing at tax time or to save money), you can claim fewer dependents or request an extra dollar amount withheld from each check. Some people in irregular income situations—freelancers or commission workers who also have a W-2 job—use this method to set aside money throughout the year.

You do not need your employer's permission to change your W-4, and you can do it as many times as you want. straightforward fill out a new W-4 form (available from your payroll department or the IRS website) and submit it. The change takes effect on your next paycheck, though some employers process it the following pay period. Keep a copy for your records.

State income tax withholding

If you live in a state with income tax, your employer withholds based on a state W-4 form. The process is similar to federal withholding but uses your state's tax brackets and rules. Some states have higher top rates than the federal government; California's top rate is 13.3 percent, for example. Others are much lower: Colorado's top rate is 4.63 percent.

A few states have special rules. New York allows you to claim a credit for taxes paid to another state if you work in one state and live in another. Pennsylvania taxes only wage and salary income, not investment income. Some states offer credits for dependents or education expenses that reduce your withholding.

You can adjust state withholding the same way you adjust federal: by submitting a new state W-4 form to your employer. If you move to a different state mid-year, notify your payroll department so they can stop withholding for your old state and start for your new one.

Social Security and Medicare taxes

These two taxes are fixed percentages and do not change based on your W-4 answers. Social Security tax is 6.2 percent of your gross pay, up to a maximum of $168,600 in annual wages for 2024 (this cap changes yearly). Once you earn $168,600 in a year, no more Social Security tax is withheld from the rest of your paychecks. Medicare tax is 1.45 percent of all gross pay with no cap.

If you earn over $200,000 (single) or $250,000 (married filing jointly), an additional 0.9 percent Medicare tax is withheld. This is called the Net Investment Income Tax, though it applies to wages as well as investment income. Your employer automatically withholds it if your pay exceeds the threshold.

You cannot adjust or reduce Social Security and Medicare withholding through your W-4. These are mandatory payroll taxes that fund Social Security retirement and disability benefits and Medicare health insurance. They appear on every paycheck as "FICA" (Federal Insurance Contributions Act) or listed separately as "Social Security" and "Medicare."

Reading your pay stub

Your pay stub shows exactly what was deducted from your paycheck. At the top is your gross pay—the amount before any deductions. Below that are line items for each deduction: federal income tax, state income tax (if applicable), Social Security, Medicare, and any voluntary deductions like health insurance premiums or retirement contributions.

The "net pay" or "take-home pay" at the bottom is what you actually receive. To understand whether you are withholding the right amount, compare your year-to-date federal tax withheld (shown on your pay stub) to your year-to-date gross pay. A rough estimate is that you should withhold about 10 to 15 percent of gross pay in federal tax, though this varies widely by income level and filing status. If you are withholding much more or much less, your W-4 may need adjustment.

Keep your pay stubs throughout the year. When you receive your W-2 in January, check that the gross pay and federal tax withheld match your pay stubs added together. If there is a discrepancy, contact your payroll department when ready.

What happens if too much or too little is withheld

If your employer withholds more federal tax than you actually owe, you will receive a refund when you file your tax return. The IRS processes most refunds within 21 days of accepting your return, though it can take longer if you claim certain credits or if your return is flagged for review. You can choose to receive your refund by direct deposit, check, or explore it to next year's taxes.

If too little is withheld and you owe money at tax time, you must pay the balance by April 15 or request a payment plan from the IRS. If you owe more than $1,000, you may also owe a penalty for under-withholding, though there are exceptions if your withholding was reasonable based on your income situation.

To avoid surprises, you can use the IRS Withholding Estimator tool on the IRS website. It asks questions about your income, filing status, and deductions, then tells you whether your current withholding is on track. If it is not, you can adjust your W-4 before the end of the year.

Frequently Asked Questions

Can I claim zero dependents to get more money in my paycheck?

Yes. Claiming zero dependents increases your federal withholding, which means less take-home pay but a larger refund at tax time. This is useful if you want to force yourself to save or if you have irregular income. However, if you actually have dependents, you may miss out on tax credits you are may have access to to when you file your return.

What if I have two jobs—do I need to adjust my W-4?

Yes. When you have multiple jobs, your total income across all jobs determines your tax bracket, but each employer withholds based only on that job's pay. This often results in under-withholding. You can fix this by claiming fewer dependents on one or both W-4s, or by requesting extra withholding on one paycheck. The IRS Withholding Estimator can help you figure out the right adjustment.

Why is my state income tax withholding different from my federal withholding?

Each state has different tax brackets, rates, and rules. Some states tax income more heavily than the federal government; others tax it less. Your state W-4 answers may also differ from your federal answers if your state has different rules about dependents or filing status. Check your state's tax website for its specific withholding tables.

Do I have to file a W-4 if I do not want any federal tax withheld?

You can request zero federal withholding by filing a W-4 with no dependents claimed and no other adjustments, but the IRS limits this option. If you have no tax liability (you owe zero tax), you can claim exemption from withholding, though you must re-certify this every year. If you do owe tax, the IRS requires at least some withholding. Talk to a tax professional about your specific situation.

When does my W-4 change take effect?

Most employers process a new W-4 on the next paycheck after you submit it, though some take up to two pay periods. Ask your payroll department for their specific timeline. If you are expecting a large refund or owe money, do not wait—submit a new W-4 as soon as you realize your withholding is off.