What goes on each line of the W-4

The W-4 has five main sections, and most homeowners only need to fill out the first three. Line 1 is your name, address, and Social Security number — straightforward identification. Line 2 asks for your filing status: single, married filing jointly, married filing separately, or head of household. Pick the one that matches your tax situation on December 31 of that year.

Line 3 is where you claim dependents — children under 17, or other relatives you support. The IRS gives you a dollar amount per dependent, and your employer uses this to reduce your withholding. If you claim dependents here, you'll see less taken from each paycheck. Line 4 and Line 5 handle other income and deductions, but most W-4 filers skip these unless they have rental income, side work, or significant itemized deductions.

Sign and date the form at the bottom. Your employer needs your signature for the form to be valid. If you're married and both working, each of you fills out your own W-4 — you don't file one jointly.

Key Takeaways

  • Line 1 is your name and Social Security number; Line 2 is your filing status; Line 3 is dependents — these three lines handle most situations.
  • Claiming dependents on Line 3 reduces the amount your employer withholds from your paycheck each pay period.
  • If you're married, each spouse fills out a separate W-4 based on their own income and withholding needs.
  • You can change your W-4 anytime — if your situation changes mid-year, submit a new one to your HR department.
  • The IRS worksheet on the back of the form helps you calculate the right withholding if you have multiple jobs or a spouse who works.

Deciding your filing status

Your filing status on the W-4 should match what you'll actually file on your tax return in April. If you're single with no dependents, you're single. If you're married and both spouses work, you can file jointly or separately — most couples file jointly because it usually results in lower taxes, but the W-4 doesn't force that choice. Head of household applies if you're unmarried, pay more than half the household expenses, and have a dependent living with you.

The status you choose on your W-4 affects how much gets withheld. Married filing jointly typically results in less withholding per paycheck than single, because the tax brackets are wider. If you're unsure which status applies to you, the IRS website has a filing status tool, or you can ask a tax preparer during tax season.

Claiming dependents and adjusting withholding

Each dependent you claim reduces your federal withholding. The IRS sets a dollar amount per dependent each year — for 2024, that's $2,300 per dependent, though this number changes annually. Your employer divides that amount by your pay periods and reduces each paycheck accordingly. If you have three children, you'd claim three dependents, and your withholding drops by roughly three times that amount spread across the year.

Only claim dependents you actually support and who live with you (with rare exceptions for parents or other relatives). Claiming dependents you don't support is tax fraud. If your custody situation changed, your marital status changed, or a dependent moved out, update your W-4 within 10 days.

Using the worksheet for complex situations

The back of the W-4 includes a worksheet for people with multiple jobs, a working spouse, or significant non-wage income. If you own rental property or have side income, the worksheet helps you calculate whether you need extra withholding to avoid owing taxes in April. You don't send the worksheet to your employer — you use it to figure out what number to put on Line 4c (other income) or Line 4d (deductions and credits).

If you're married and both working, the worksheet also helps you decide how to split withholding between your two jobs. Some couples have one spouse claim all the dependents and the other claim none, which can reduce the chance of underwithholding. The worksheet walks you through that math.

When to submit a new W-4

You submit your first W-4 when you start a job. After that, you only need to submit a new one if something changes: you get married or divorced, you have a child, you buy a house (which may affect your deductions), or you realize you're withholding too much or too little. You can also submit a new W-4 if you change jobs and want to adjust your withholding based on your new salary.

Give the new W-4 to your HR or payroll department. It takes effect on your next paycheck, though some employers process it within a few days. Keep a copy for your records. If you're changing jobs, don't assume your new employer will withhold the same amount — salaries differ, and you may need to adjust.

Common mistakes to avoid

The most common mistake is claiming too many dependents to get a bigger paycheck, then owing a large amount in April. The IRS penalizes underwithholding, and you may owe interest on top of the taxes owed. The opposite mistake — claiming zero dependents when you have children — results in too much withheld and a large refund, which is your own money returned to you late.

Another mistake is not updating your W-4 after major life changes. If you get married mid-year and don't update, you'll withhold at the single rate all year, which can create an April surprise. Similarly, if you buy a house and itemize deductions, you may need to adjust Line 5 to account for the mortgage interest deduction.

Don't confuse the W-4 with the W-2. The W-4 is what you fill out to tell your employer how much to withhold. The W-2 is what your employer sends you in January showing how much was actually withheld — you use that to file your tax return.

What happens after you submit

Your employer uses the W-4 to calculate your federal withholding for each paycheck. You can see the result on your pay stub — look for the line labeled "Federal Income Tax Withheld" or "FIT." If you submitted a new W-4 mid-year, the withholding amount changes on your next paycheck. There's no approval process; your employer just implements what you've told them.

In January of the following year, your employer sends you a W-2 showing your total income and total federal withholding for the year. You use that W-2 to file your tax return. If too much was withheld, you get a refund. If too little was withheld, you owe. The W-4 is your tool to try to get that balance right throughout the year rather than settling it all in April.

Frequently Asked Questions

Should I claim zero dependents to get a bigger paycheck?

No. Claiming dependents you actually have reduces your withholding and gives you more money each pay period, which is correct. Claiming zero when you have dependents means too much is withheld, and you'll get a large refund in April — that's your own money returned late. Claim the dependents you actually support.

Can I change my W-4 in the middle of the year?

Yes. Submit a new W-4 to your HR department anytime your situation changes — marriage, divorce, new child, new job, or if you realize your withholding is wrong. The new withholding takes effect on your next paycheck. You can change it as many times as you need.

What if I'm married and my spouse also works?

Each of you fills out your own W-4 based on your income. The IRS worksheet on the back helps you coordinate withholding between two jobs so you don't underwithhold. Some couples have one spouse claim all dependents and the other claim none, which can prevent owing taxes in April.

Do I need to claim my mortgage as a dependent?

No. A mortgage is not a dependent. Dependents are people — children under 17, or other relatives you support. Mortgage interest may reduce your taxes if you itemize deductions, but that's handled separately on your tax return, not on the W-4.

What if I don't have a Social Security number yet?

You need a Social Security number to work legally in the United States and to fill out a W-4. If you're a new immigrant, you can apply for one through the Social Security Administration. Until you have one, you cannot start employment.