What goes on each line of the W-4

The W-4 has six main sections, and most people only need to fill in a few of them. Line 1 is your name, address, and Social Security number — exactly as they appear on your Social Security card. 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. Each dependent reduces the tax your employer withholds. Line 4 is for other income: if you have a second job, rental income, or self-employment earnings, you list them here so your employer knows to withhold enough to cover your total tax bill. Line 5 is for deductions you plan to claim — but only fill this in if you don't take the standard deduction, which most people do.

Line 6 is for extra withholding: if you want your employer to take out more tax each paycheck, write the dollar amount here. This is useful if you know you'll owe money at tax time, or if you want a refund. Sign and date at the bottom, and give it to your HR or payroll department.

Key Takeaways

  • Line 1 requires your name, address, and Social Security number exactly as they appear on your Social Security card.
  • Line 2 is your filing status — single, married filing jointly, married filing separately, or head of household — as of December 31.
  • Line 3 is where you claim dependents, which lowers the amount your employer withholds from each paycheck.
  • Line 4 covers other income sources like a second job or self-employment, so your employer withholds enough for your full tax liability.
  • Line 6 lets you request extra withholding if you want more tax taken out each pay period.

When to update your W-4

You don't have to file a new W-4 every year. You only need to update it when your life changes in a way that affects your taxes. That includes getting married or divorced, having a child, taking a second job, or a major change in income. You should also update it if you got a large refund or owed money last year — that's a sign your withholding is off.

When you start a new job, your new employer will ask you to fill out a W-4 before your first paycheck. If you don't submit one, they'll withhold taxes as if you're single with no dependents, which is usually too much. Submit it as soon as you can to avoid overpaying.

Dependents and Line 3

A dependent is someone you support financially and claim on your tax return. For most people, this means children under 17. You can also claim other relatives — like a parent or sibling — if they live with you for the whole year, you pay more than half their living costs, and they earn less than a certain amount (this limit changes yearly, so check the IRS website for the current number).

Each dependent you claim on Line 3 reduces your withholding. The more dependents you list, the less tax comes out of each paycheck. But be honest: if you claim dependents you don't actually support, you'll owe money at tax time, plus penalties.

Other income and Line 4

Line 4 is critical if you have income beyond your main job. This includes a second W-2 job, self-employment income, rental income, or significant investment income. If you don't report this, your employer will only withhold enough for your main job's salary, and you'll face a big tax bill in April.

The W-4 worksheet (included with the form) helps you calculate how much extra withholding you need. If you have a second job, you can either increase withholding at your main job or ask your second employer to withhold extra. Many people find it easier to have the second employer withhold extra, since that's where the extra income comes from.

Extra withholding on Line 6

Line 6 lets you ask your employer to take out additional money from each paycheck beyond what the standard calculation requires. This is useful if you know you'll owe taxes — for instance, if you have self-employment income that isn't being withheld, or if you got a large refund last year and want to break even instead.

You can request any dollar amount. If you want an extra $50 per paycheck, write 50. If you want an extra $200 per month, divide by the number of pay periods and write that number. This is one of the simplest ways to adjust your withholding without changing your filing status or dependents.

Common mistakes to avoid

The most common error is writing your name or Social Security number incorrectly on Line 1. Even a small typo can cause your W-4 to be rejected or matched to the wrong person in the IRS system. Double-check before you hand it in. Another frequent mistake is claiming dependents you're not may have access to to — the IRS cross-checks this against tax returns, and if you claimed someone you shouldn't have, you'll owe back taxes plus interest and penalties.

People also sometimes forget to update their W-4 after a major life change. If you got married, had a child, or took a second job and didn't file a new W-4, your withholding will be wrong. It's worth spending five minutes to update it rather than facing a surprise bill or waiting months for a refund.

Finally, don't leave Line 4 blank if you have other income. This is where many people accidentally underpay their taxes. If you're unsure whether something counts as "other income," ask your payroll department or check the IRS website.

Frequently Asked Questions

What happens if I don't fill out a W-4?

Your employer is required to withhold taxes from your paycheck. If you don't submit a W-4, they'll use the default withholding, which treats you as single with no dependents and no other income. This usually results in too much tax being withheld, and you'll get a refund when you file your return — but you won't see that money until April.

Can I claim zero dependents even if I have children?

Yes, you can claim fewer dependents than you're may have access to to. This increases your withholding and usually results in a refund. Some people do this intentionally as a way to save money. However, if you claim more dependents than you actually have, you'll owe money at tax time.

Do I need to file a new W-4 every year?

No. You only need to update your W-4 when something changes — a new job, marriage, divorce, a child, a second job, or a major income change. If nothing has changed, your current W-4 stays in effect.

What's the difference between filing status and dependents?

Filing status (Line 2) describes your marital and household situation and determines your tax brackets. Dependents (Line 3) are people you support financially. You can be married with no dependents, or single with three dependents — they're separate things.

Can I request extra withholding if I'm worried I'll owe taxes?

Yes. Line 6 is designed for this. If you have self-employment income, investment income, or other sources not being withheld, you can request extra withholding on Line 6 to cover what you'll owe. You can adjust the amount anytime by filing a new W-4.