What goes on each line of the W-4

The W-4 has five main sections. Start with your name, address, and Social Security number at the top — this is straightforward identification. Line 1 asks for your full name as it appears on your Social Security card. Line 2 is your address. Line 3 is your Social Security number. These three pieces tell your employer and the IRS who you are.

Line 4 asks for your filing status: Single, Married Filing Jointly, Married Filing Separately, or Head of Household. This is the status you plan to use on your tax return, not your current legal status. If you're married but file separately from your spouse, you select Married Filing Separately. If you're single and supporting dependents, Head of Household usually gives you a better tax outcome than Single. Pick the status that matches how you'll actually file your return.

Lines 5 and 6 are where most people make mistakes. Line 5 asks you to list dependents — children under 17, and other relatives you claim. Line 6 asks about other income: a second job, a spouse's income if you're married filing jointly, or investment income. These numbers tell your employer how much of your paycheck to withhold for taxes. If you skip them, your employer withholds as if you have no dependents and no other income, which usually means too much comes out of each check.

Key Takeaways

  • Your filing status on the W-4 should match the status you plan to use on your tax return, not your current marital status.
  • Claiming dependents and reporting other income on lines 5 and 6 reduces how much your employer withholds from each paycheck.
  • If you have a second job or your spouse works, you need to account for that income or you will owe taxes at the end of the year.
  • You can adjust your W-4 whenever your situation changes — marriage, a new job, a child born — without waiting for the new year.
  • Withholding too little means you owe money in April; withholding too much means you get a refund but gave the government an interest-free loan.

How to handle dependents correctly

Line 5 is for dependents you claim on your tax return. A dependent is usually a child under 17, but can also be an adult relative you support — a parent, a sibling, a grandchild. You can only claim someone as a dependent if you provide more than half their financial support for the year and they live with you (with some exceptions for relatives who don't live with you).

Count only the dependents you actually plan to claim. If you're divorced and share custody, only the parent who claims the child on the tax return should list that child on the W-4. If you're unsure whether you can claim someone, work that out before you fill out the form — the IRS has a Dependent Exemption Worksheet on their website that walks through the rules. Claiming dependents you don't actually claim on your return creates a mismatch that can trigger an audit.

Accounting for a second job or spouse's income

Line 6 is critical if you have more than one source of income. If you work two jobs, both employers will withhold taxes based on what you tell them, but neither knows about the other job. This means you could end up underpaying if your combined income pushes you into a higher tax bracket.

The same problem happens if you're married filing jointly and both spouses work. Each employer withholds based on the income from that job alone. If your household income is high enough to hit a higher tax bracket, you need to account for that on at least one of the W-4s. Line 6 lets you tell your employer to withhold extra money to cover the other income. You can put a dollar amount there — for example, if your spouse makes $30,000 a year, you might put $500 or $1,000 on line 6 to have extra withheld from your paycheck.

Understanding the worksheets and adjustments

The W-4 includes worksheets on the back to help you calculate the right withholding. Most people don't need them. If you have a straightforward situation — one job, no dependents, no other income — you can fill out the form without the worksheets. If you have dependents, multiple jobs, or significant other income, the worksheets walk you through the math.

The worksheets ask you to estimate your total tax liability for the year, then work backward to figure out how much should come out of each paycheck. This is more accurate than guessing, but it takes time. The IRS also has a withholding calculator on their website (irs.gov/w4app) that does this calculation for you — you answer questions about your situation and it tells you what to put on each line.

When to submit a new W-4

You don't have to wait for January 1 to change your W-4. Submit a new one whenever your situation changes: you get married, you have a child, you take a second job, your spouse loses a job, you claim a dependent who ages out, or you realize your withholding is way off. Your employer processes the new W-4 within a few pay periods, and the new withholding takes effect on the next paycheck after that.

If you're between jobs, you don't need to do anything — your new employer will ask you to fill out a W-4 on your first day. If you're self-employed or a contractor, you don't file a W-4 at all; instead, you make quarterly estimated tax payments to the IRS.

Common mistakes to avoid

The most common mistake is leaving line 5 blank when you have dependents. This tells your employer you have no dependents, so they withhold more than necessary. You'll get a refund in April, but that's money you could have used throughout the year.

The second mistake is not accounting for a second job or spouse's income. If you have two jobs and both employers withhold based on a single job's income, you can end up owing money in April. Use line 6 to have extra withheld, or use the IRS withholding calculator to figure out the right amount.

A third mistake is claiming dependents you don't actually claim on your return. This creates a mismatch that the IRS will catch when they match your W-4 to your tax return. Claim only the dependents you plan to list on your return.

What happens after you submit the W-4

Your employer keeps the W-4 on file and uses it to calculate your withholding for every paycheck. At the end of the year, your employer sends you a W-2 form that shows how much you earned and how much was withheld. You use the W-2 to file your tax return. If your withholding was too high, you get a refund. If it was too low, you owe money.

The goal is to get as close as possible to zero — withholding just enough that you don't owe and don't get a large refund. This takes some trial and error, especially if your income or situation changes during the year. If you got a big refund last year, adjust your W-4 to withhold less. If you owed money, adjust it to withhold more.

Frequently Asked Questions

What's the difference between filing status on the W-4 and my actual marital status?

Filing status on the W-4 is about how you'll file your tax return, not your legal status. You might be married but file separately from your spouse for tax reasons. You might be single but claim Head of Household if you support dependents. Pick the status that matches your tax return, not your marriage certificate.

Can I claim a dependent on my W-4 if I'm not sure I can claim them on my tax return?

No. Only claim dependents you actually plan to list on your return. If you claim someone on the W-4 but not on your return, the IRS will notice the mismatch. If you're unsure, use the IRS Dependent Exemption Worksheet or talk to a tax professional before you fill out the form.

What do I do if I have two jobs and don't want to do the math?

Use the IRS withholding calculator at irs.gov/w4app. Answer questions about your situation and it tells you what to put on each line of both W-4s. This is faster and more accurate than trying to figure it out yourself.

If I change my W-4, when does the new withholding start?

Your employer processes the new W-4 within a few pay periods, and the new withholding takes effect on the next paycheck after that. If you need the change to happen quickly, tell your HR department so they can prioritize it.

What if I'm married and my spouse also works — do we both need to adjust our W-4s?

You only need to adjust one of them. On one spouse's W-4, use line 6 to account for the other spouse's income. This tells that employer to withhold extra to cover the combined household income. The other spouse's W-4 can stay standard.