The right withholding amount depends on your filing status, number of dependents, and other income sources

Your employer withholds federal income tax from each paycheck based on information you provide on Form W-4. The amount withheld is not a fixed percentage — it changes based on your household situation, whether you have a second job, and whether you receive income outside your paycheck. The goal is to withhold enough so you do not owe a large amount on April 15, but not so much that you give the IRS an interest-free loan all year.

The IRS provides a W-4 worksheet to help you calculate the right amount. You fill it out when you start a job and can update it whenever your situation changes — a marriage, a child, a second job, or a major change in income. Most people adjust their withholding zero to three times in their working life, but some situations require more frequent changes.

Key Takeaways

  • Form W-4 is where you tell your employer how much federal tax to withhold; you fill it out when hired and can change it anytime your situation changes.
  • The IRS W-4 worksheet walks you through calculating withholding based on filing status, dependents, multiple jobs, and non-wage income like interest or self-employment earnings.
  • Underwithholding means you owe money in April; overwithholding means you get a refund but lose access to that money for months.
  • If you have a spouse who works, both of you working affects how much each should withhold, and the worksheet accounts for this.
  • You can request extra withholding on Form W-4 if you expect to owe, or claim fewer allowances to increase withholding without doing the full calculation.

How the W-4 worksheet calculates your withholding

The current W-4 form (redesigned in 2020) does not use "allowances" or "exemptions" the way older versions did. Instead, you enter your filing status, number of dependents, and income from other jobs or sources. The worksheet then estimates your annual tax liability and divides it by the number of pay periods to arrive at a per-paycheck amount.

The worksheet has five main steps. First, you select your filing status: single, married filing jointly, married filing separately, or head of household. Second, you claim dependents — children under 17 and other relatives who meet IRS rules. Third, you account for other income: a spouse's wages, investment income, self-employment income, or retirement distributions. Fourth, you list other jobs (yours or your spouse's). Fifth, you can request extra withholding if you want a safety margin.

The IRS provides the worksheet on Form W-4 itself, and also publishes a detailed version on IRS.gov. You do not need to submit the worksheet to your employer — only the completed W-4 form. Keep the worksheet for your records in case you need to explain your withholding later.

When you have a spouse who also works

If both spouses earn wages, the combined income affects the tax bracket you fall into, which changes how much each paycheck should have withheld. The W-4 worksheet includes a step specifically for this: if you are married filing jointly and both spouses work, you enter both salaries and the worksheet calculates a combined withholding amount. You and your spouse then decide how to split that amount between your two paychecks.

A common approach is to have one spouse claim all the dependents and request the full withholding amount, while the other spouse uses the "married, but withhold at single rate" option. Another approach is to split the withholding evenly. The key is that your combined withholding across both jobs should equal what the worksheet says you need.

If you do not account for a spouse's income, you will likely underwithhold and owe money in April. The worksheet prevents this by asking you to enter both salaries upfront.

Adjusting withholding when you have multiple jobs

A second job, a seasonal job, or a spouse's job changes your tax picture because your total income is higher. The W-4 worksheet has a line for "other jobs" — you enter how many other jobs you or your spouse have, and the worksheet increases your withholding to account for the higher income.

If you do not adjust your withholding and you have two jobs, you will almost certainly underwithhold. Each employer withholds based only on the income from that job, so neither one knows about the other. The IRS sees your combined income at tax time and you owe the difference.

The simplest fix is to request extra withholding on one of the paychecks — usually the smaller one. You can enter a dollar amount on line 4(c) of Form W-4 to have that amount withheld from every paycheck. If you earn $500 extra per month from a second job, requesting an extra $100 per paycheck from your main job is a straightforward way to cover it.

Self-employment income and other non-wage income

If you have self-employment income — from freelance work, a side business, or gig work — you do not receive a W-2 and your employer does not withhold anything. The W-4 worksheet asks whether you have income from self-employment, rental property, or other sources. You enter an estimate of that income, and the worksheet increases your withholding from your W-2 job to cover the tax on both sources.

Self-employment income is also subject to self-employment tax (Social Security and Medicare), which is separate from income tax. The W-4 worksheet does not calculate self-employment tax — you handle that when you file your return or make quarterly estimated tax payments. But for federal income tax withholding purposes, the worksheet helps you avoid a large bill in April.

If your self-employment income is substantial or unpredictable, you may want to request extra withholding on your W-2 paycheck as a buffer, rather than relying on the worksheet estimate alone.

Requesting extra withholding or claiming fewer allowances

If you expect to owe money in April — because you have a large bonus coming, investment income, or income the worksheet does not fully account for — you can request extra withholding. On Form W-4, line 4(c), you enter a dollar amount to be withheld from each paycheck in addition to the calculated amount.

For example, if you expect a $5,000 bonus in December and you are paid biweekly (26 paychecks per year), you could request an extra $192 per paycheck to cover the tax on that bonus. This is a straightforward way to avoid a surprise bill.

You can also request extra withholding as a percentage of your gross pay, though this is less common. Some employers allow you to specify a percentage on the W-4 form itself.

How to update your W-4 when your situation changes

You can submit a new W-4 to your employer anytime — there is no limit on how often you can change it. Common reasons to update include: a marriage or divorce, the birth or adoption of a child, a significant change in income, taking a second job, or a spouse leaving the workforce.

The change takes effect on the next paycheck after your employer receives the form, though some employers may delay it by one or two pay periods depending on their payroll system. If you are expecting a refund and want to reduce it, or if you owe money and want to increase withholding, updating your W-4 mid-year will affect your remaining paychecks but not the ones already processed.

You do not need to file a new W-4 every year unless your situation changes. If nothing has changed, your current W-4 stays in effect until you submit a new one.

The trade-off between underwithholding and overwithholding

Underwithholding means you do not have enough withheld during the year, so you owe money when you file your return in April. You may also owe a penalty if you significantly underpaid. Overwithholding means you have too much withheld, so you receive a refund — but that refund is your own money that you could have used during the year.

There is no "correct" amount in an absolute sense. Some people prefer to overwithhold slightly and get a refund, viewing it as forced savings. Others prefer to underwithhold slightly and keep more money in their paycheck, as long as they do not owe a penalty. The W-4 worksheet is designed to get you close to zero — neither a large refund nor a large bill — but you can adjust from there based on your preference.

If you have a history of owing money or receiving large refunds, updating your W-4 based on the worksheet should bring you closer to breaking even.

Frequently Asked Questions

What happens if I do not fill out a W-4?

Your employer is required to withhold federal income tax, so if you do not submit a W-4, they will withhold at the highest rate — as if you are single with no dependents. This usually results in overwithholding and a large refund. You should submit a W-4 as soon as you are hired to avoid this.

Can I claim zero dependents to increase my withholding?

The new W-4 form does not use "claiming dependents" in the old sense. You enter your actual number of dependents on the form. If you want extra withholding beyond what the worksheet calculates, use line 4(c) to request a specific dollar amount per paycheck instead.

Do I need to update my W-4 every year?

No. You only need to update your W-4 when your situation changes — a marriage, a child, a job change, or a significant income change. If nothing has changed, your current W-4 remains in effect indefinitely.

What if my withholding is too high and I want a bigger paycheck?

Submit a new W-4 to your employer and adjust your withholding downward. The worksheet will help you calculate the right amount based on your current situation. You can also reduce any extra withholding you requested on line 4(c).

How do I know if my withholding is correct?

After you file your tax return, look at your refund or the amount you owed. If you received a large refund or owed a large amount, your withholding was off. Use the W-4 worksheet again and submit a new form to adjust it for the next year.