What Is FWH: Federal Withholding, Your W-4, and Exemptions

FWH on a pay stub stands for federal withholding: the federal income tax your employer takes out of each paycheck and forwards to the IRS on your behalf. The dollar amount next to it changes with your gross pay, your filing status, and what you put on Form W-4. It’s separate from Social Security and Medicare, and it’s the one federal deduction you actually have control over.

What the FWH Line Represents

The U.S. income tax system is pay-as-you-go. You owe tax as you earn income, not in a single bill at the end of the year.¹ FWH is how that works for employees. Every pay period your employer calculates a portion of your wages, holds it back, and sends it to the Treasury under your Social Security number. When you file your return the next spring, that total gets credited against your actual tax liability.

Your employer runs the calculation using tables the IRS publishes in Publication 15-T, based on your pay frequency, filing status, and the entries on your W-4.² The underlying rates for 2026 run from 10% on the first $12,400 of taxable income for a single filer up to 37% on income above $640,600.³ You don’t do the math yourself; you just tell your employer, through the W-4, how to do it for you.

FWH Is Not Social Security or Medicare

Most pay stubs list several federal deductions, and it’s easy to mistake one for another. FWH covers only federal income tax. The FICA lines cover Social Security and Medicare, which are separate programs with fixed rates.

For 2026, Social Security tax runs 6.2% on wages up to $184,500, and Medicare tax runs 1.45% on all wages, with your employer matching both.⁴ If your wages pass $200,000 in a calendar year, an additional 0.9% Medicare tax is withheld from the excess, with no employer match.⁵

The practical point: FICA rates are the same for everyone and you can’t adjust them. FWH varies with your income and choices, and you can change it whenever you want by turning in a new W-4.

What Controls the FWH Amount: Your W-4

Form W-4, the Employee’s Withholding Certificate, is what tells your employer how much to withhold.⁶ You usually fill one out at onboarding, and you can submit a new one any time. The form has five steps:

Step 1 collects your name, address, Social Security number, and filing status (single, married filing jointly, or head of household).
Step 2 asks whether you hold multiple jobs or your spouse also works. This step trips people up the most.
Step 3 is for dependents. Claiming qualifying children or other dependents lowers the amount withheld each pay period.
Step 4 is optional and covers non-wage income (interest, dividends, retirement distributions), itemized deductions you expect to claim, and any extra flat amount you want withheld per paycheck.
Step 5 is your signature.

If you never turn in a W-4, your employer must withhold as though you’re a single filer taking only the standard deduction with no adjustments.⁷ For many people, especially anyone married or claiming dependents, that default withholds more than necessary.

When to Update Your W-4

Withholding gets out of sync when your life changes. Common triggers are marriage, divorce, the birth or adoption of a child, buying a home, picking up a second job, or a jump in non-wage income like investment gains or self-employment earnings.⁸

If a change means you’re entitled to less withholding than before, you’re required to submit a new W-4 within 10 days.⁸ There’s no rule against updating more often. The IRS Tax Withholding Estimator at irs.gov/W4App will run through a scenario using your latest pay stub and tell you whether to raise or lower your withholding, plus a specific figure to enter on a new form.⁹ Running it once a year, ideally early in the year, is enough for most people.

Situations That Throw FWH Off

Multiple Jobs or a Working Spouse

Withholding tables assume each W-4 covers your only wage income. When you or your spouse hold more than one job, each employer withholds as if its paycheck is all you earn, which stacks the lower brackets twice and usually leaves you short at tax time. Step 2 of the W-4 gives you three ways to fix that:¹⁰

Use the IRS Tax Withholding Estimator. This is the most accurate route, particularly when either spouse has self-employment income, and it produces a specific dollar amount to enter in Step 4(c).
Complete the Multiple Jobs Worksheet on page 3 of the W-4. You look up a figure using wages from your highest- and lowest-paying jobs, divide by the number of pay periods left, and enter the result in Step 4(c) on the W-4 for your highest-paying job only.
Check the box in Step 2(c). This option is only available when there are exactly two jobs total, both W-4s need the box checked, and it works best when the two jobs pay roughly the same.

Whichever method you use, complete Steps 3 and 4(b) on the W-4 for the highest-paying job only, and leave those steps blank on the forms for the other jobs.¹⁰

Bonuses, Commissions, and Other Supplemental Wages

Bonuses, commissions, overtime, back pay, and severance count as supplemental wages, and different rules apply. When your employer pays them separately from regular wages, or identifies them separately on the stub, it can apply a flat 22% federal withholding rate rather than running the payment through the regular tables.¹¹ That flat rate is convenient but rarely exact: if your marginal rate is 12%, you’ll get some of it back at filing; if it’s 32%, you’ll owe the difference.

A second rule takes over once supplemental wages from a single employer top $1 million in a calendar year. Everything above that is withheld at 37%, the top rate, no matter what your W-4 says.¹¹

Claiming Exempt From FWH

If you had no federal income tax liability last year and expect none this year, you can claim exemption. You check the exemption box below Step 4(c) on Form W-4 and complete only Steps 1(a), 1(b), and 5.¹⁰ Your employer will then withhold nothing for federal income tax, though FICA still comes out.

Exempt status has an expiration date. An exemption claimed for 2026 expires on February 16, 2027. If you don’t file a new W-4 by then, your employer must start withholding as if you had submitted a W-4 with no adjustments.¹⁰ Exempt makes sense for students, very low earners, or retirees with income under the filing threshold. Claiming it when you actually owe tax leads to a full balance plus possible penalties at filing.

Avoiding a Surprise Bill or Penalty

If your withholding falls too far short of your total tax, the IRS can charge an underpayment penalty that accrues interest until the balance is paid.¹² You can avoid the penalty by meeting any one of these safe harbors:

You owe less than $1,000 after subtracting withholding and credits from your total tax.
You paid at least 90% of the tax you owe for the current year.
You paid at least 100% of the tax shown on last year’s return, or 110% if your adjusted gross income was over $150,000 ($75,000 if married filing separately).

The prior-year rule is the easiest to hit because it doesn’t require you to guess this year’s income.¹³ If your pay went up mid-year and you’re worried about coming up short, the simplest fix is to raise the extra amount in Step 4(c) of your W-4. Extra withholding through your paycheck is treated as paid evenly across the year, even if you only increase it in December, which is why it’s a cleaner catch-up tool than a fourth-quarter estimated payment.

Reconciling FWH at Tax Time

After the year ends, your employer reports total wages in Box 1 of your W-2 and total FWH in Box 2.¹⁴ The W-2 is due to you by January 31. On your Form 1040 you add up federal tax withheld from all W-2s and any 1099s that show withholding, then compare that total to your calculated tax.

If withholding exceeded what you owe, the difference comes back as a refund. If it fell short, you pay the balance by the filing deadline. A big refund means you overpaid all year and effectively lent the government money interest-free. A big balance means your W-4 didn’t account for enough of your income, and past the safe harbor thresholds it can trigger an underpayment penalty on top of what you owe. Checking the withholding estimator once a year is what keeps the FWH line on your pay stub landing where you actually want it.

1
Internal Revenue Service. Pay As You Go, So You Won’t Owe: A Guide to Withholding, Estimated Taxes and Ways to Avoid the Estimated Tax Penalty
2
Internal Revenue Service. Publication 15-T (2026), Federal Income Tax Withholding Methods
3
Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
4
Social Security Administration. 2026 Cost-of-Living Adjustment (COLA) Fact Sheet
5
Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates
6
Internal Revenue Service. About Form W-4, Employee’s Withholding Certificate
7
Office of the Law Revision Counsel. 26 USC Ch. 24 – Collection of Income Tax at Source on Wages
8
Internal Revenue Service. Publication 505 (2025), Tax Withholding and Estimated Tax
9
Internal Revenue Service. Tax Withholding Estimator
10
Internal Revenue Service. Form W-4 (2026), Employee’s Withholding Certificate
11
Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide
12
Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty
13
Internal Revenue Service. Estimated Taxes
14
Internal Revenue Service. General Instructions for Forms W-2 and W-3 (2026) – Section: Specific Instructions for Form W-2