Form W-4 for Employers: Rules, Steps and Withholding Basics

Form W-4, the Employee's Withholding Certificate, is the IRS form an employee fills out so you know how much federal income tax to withhold from their pay. As the employer, you collect it at hire, apply it to payroll using the tables in IRS Publication 15-T, keep it on file, and follow special rules when a form is missing, invalid, claims exemption or is overridden by an IRS lock-in letter.

This article is general information, not legal advice.

Key takeaways

• Ask every new employee for a signed Form W-4 and make it effective with the first wage payment.
• If an employee gives you no Form W-4, withhold as if they checked Single or Married filing separately and made no other entries.
• Exempt status lasts one calendar year; the employee must give you a new form by February 15 to stay exempt.
• An IRS lock-in letter overrides any later Form W-4 that would lower withholding.
• Form W-4 covers federal income tax only, so state withholding may need a separate state certificate.

What is Form W-4 and who fills it out?

Form W-4 is a federal withholding certificate that the employee completes and gives to the employer. It is not filed with the IRS as a routine matter; you keep it and use it to set federal income tax withholding.

The IRS About Form W-4 page explains that the form tells the employer how much federal income tax to withhold and suggests that employees complete a new one each year and whenever their personal or financial situation changes. Federal income tax withholding is only one part of payroll. Social Security and Medicare taxes are figured separately and do not depend on the W-4, a distinction covered in our guide to income tax vs payroll tax.

Only employees complete a Form W-4. Independent contractors do not, which is one reason worker classification matters before onboarding paperwork begins. If you are unsure how a worker should be treated, review the federal and state tests for employee vs independent contractor status first.

Since 2020 the form has no withholding allowances, but forms from 2019 or earlier stay in effect until the employee gives you a newer one, according to IRS Publication 15 (Circular E).

What are the five steps on Form W-4?

The current form has five steps, and only Steps 1 and 5 are required for every employee. Steps 2 through 4 are completed only if they apply, as the 2026 Form W-4 states on its face.

Step	What the employee enters	What it changes for payroll
Step 1: Personal information	Name, address, SSN and filing status (Single or Married filing separately, Married filing jointly or Qualifying surviving spouse, or Head of household)	Sets the standard deduction and tax rates used in the calculation
Step 2: Multiple jobs or spouse works	One of three options: the IRS estimator, the Multiple Jobs Worksheet result in Step 4(c), or the two-jobs checkbox	Raises withholding to account for combined household income
Step 3: Claim dependent and other credits	Dollar amount for qualifying children under 17, other dependents and other credits	Reduces the annual tax used to figure withholding
Step 4: Other adjustments	4(a) other income, 4(b) deductions beyond the standard deduction, 4(c) extra withholding per pay period	4(a) increases withholding, 4(b) reduces it, 4(c) adds a flat amount
Step 5: Sign here	Employee signature and date under penalties of perjury	The form is not valid unless signed

The 2026 form also has a separate "Exempt from withholding" section where an eligible employee checks a box. The Deductions Worksheet used for Step 4(b) now includes lines for qualified tips, qualified overtime compensation and an amount for seniors age 65 or older, so employees in tipped or overtime-heavy roles may enter larger 4(b) amounts than before.

Below Step 5 is an "Employers Only" box for your name and address, the employee's first date of employment and your EIN. Fill it in when you use the W-4 for state new hire reporting, since Publication 15 notes that many states accept a copy of Form W-4 with employer information added.

What are an employer's responsibilities for Form W-4?

You request the form, apply it on time, handle missing, invalid and exempt forms, follow IRS notices and keep records. Rules below come from Publication 15 unless noted.

Collect it at hire

Ask all new employees to give you a signed Form W-4 when they start work and make it effective with the first wage payment. This belongs on your onboarding list next to the I-9; if you verify documents remotely, see our note on Form I-9 remote document examination.

Treat a missing form as Single with no adjustments

If a new employee (including a rehire) does not give you a completed Form W-4, withhold as if they checked Single or Married filing separately in Step 1(c) and made no entries in Steps 2, 3 or 4. An employee paid wages before 2020 who never furnished a form continues to be treated as single with zero allowances on a 2019 form, unless you use the optional computational bridge in Publication 15-T.

Apply replacement forms on time

When an employee gives you a new form that replaces an existing one, begin withholding under it no later than the start of the first payroll period ending on or after the 30th day after you received it. Do not adjust withholding for earlier pay periods.

Reject invalid forms

Any unauthorized change or addition to the form makes it invalid, including removing the certification language. A form is also invalid if the employee clearly indicates it is false by the time they give it to you. When you receive an invalid form, do not use it. Tell the employee it is invalid and ask for another. If they do not provide a valid one, keep withholding under their earlier valid form, or, if there is none, withhold as Single or Married filing separately with no other entries.

Track exempt status renewals by February 15

An employee may claim exemption only if they had no federal income tax liability last year and expect none this year. Exempt wages are still subject to Social Security and Medicare taxes. A form claiming exemption is effective only for that calendar year. To stay exempt, the employee must give you a new form by February 15. If they do not, begin withholding as if they checked Single or Married filing separately with no other entries. If a new exempt form arrives on February 16 or later, you may apply it to future wages but must not refund tax already withheld. The 2026 form itself tells employees to submit a new one by February 16, 2027.

Follow lock-in letters

A lock-in letter is an IRS notice telling you the maximum filing status and withholding to use for a specific employee who has been seriously underwithheld. Publication 15 requires you to give the employee copy to a current employee within 10 business days of receipt and to begin withholding under the notice for wages paid after the date it specifies, not immediately. The IRS withholding compliance questions and answers page says that date is no sooner than 60 calendar days after the letter date, and that employers who fail to follow a lock-in letter are liable for the tax that should have been withheld.

After a lock-in letter, ignore any new Form W-4 that claims exemption or results in less withholding than the notice requires; the employee must contact the IRS instead. Honor a new form that results in more withholding.

Keep the records for at least 4 years

Keep copies of employees' withholding certificates along with all employment tax records for at least 4 years and make them available for IRS review. If the IRS asks, you must make original forms available for inspection or send copies as directed. For multistate teams, align this with state retention rules using our guide to multistate HR records retention.

Check state withholding forms

Form W-4 sets federal withholding only. Some states require their own certificate. California, for example, states on its DE 4 form that since January 1, 2020 the federal W-4 is used for federal withholding only and employees must file the DE 4 for California personal income tax withholding. Check each state where you have employees, and see our guide to running multi-state payroll with conflicting tax rules.

How is federal withholding calculated from Form W-4?

You combine the employee's W-4 entries with the withholding tables in IRS Publication 15-T, which offers a percentage method and a wage bracket method. Most payroll software applies the percentage method automatically.

Section 1 of Publication 15-T holds the percentage method tables for automated payroll (Worksheet 1A). Sections 2 through 5 cover manual payroll with wage bracket or percentage tables, split by 2020 or later and 2019 or earlier forms. Section 6 covers alternative methods.

In plain terms, the automated percentage method works like this:

1. Annualize the employee's taxable wages for the pay period.
2. Add Step 4(a) other income, subtract Step 4(b) deductions and, if the Step 2 box is not checked, subtract a fixed amount set in Worksheet 1A.
3. Find the annual tax in the table for the employee's filing status (there are separate tables for when the Step 2 box is checked) and divide by pay periods.
4. Subtract the Step 3 credits, divided by pay periods.
5. Add any Step 4(c) extra withholding.

For employees still on a 2019 or earlier form, you may use the optional computational bridge, which converts old entries into 2020 or later equivalents. For nonresident aliens, Publication 15-T adds an amount to wages only for figuring withholding.

If you collect forms electronically, Publication 15-T lists requirements: the system must replicate the official form text, capture an electronic signature, provide an exemption checkbox and a nonresident alien field, and produce a hard copy if the IRS asks. Then confirm your payroll tax deposit schedule is right as well.

Common mistakes employers make with Form W-4

Most W-4 problems come from process gaps rather than tax math. Watch for these:

• Using a homemade or edited form. Substitute forms must match the official language. Forms developed by employees are treated as if no form was furnished.
• Accepting a fixed dollar or percentage request. Employees cannot base withholding on a flat amount or percentage alone. They may add extra withholding in Step 4(c) on top of the calculated amount.
• Taking estimated tax payments through payroll. Publication 15 says not to accept extra withholding or estimated payments outside the employee's Form W-4.
• Letting exempt status roll over. Without a new form by February 15, exempt employees must go back to default withholding.
• Applying a lower W-4 after a lock-in letter. This makes you liable for the shortfall.
• Forgetting the state form. A federal W-4 does not set state withholding where the state uses its own certificate.

When should employees submit a new Form W-4?

Employees should submit a new form when their personal or financial situation changes, and an exempt employee must submit one every year by February 15 to remain exempt. Publication 15 also encourages employers to remind staff each year, especially if they owed tax or got a large refund.

FAQ

Do employers send Form W-4 to the IRS?

Not routinely. You keep it in your records and send copies only when the IRS asks in writing or through published guidance.

What happens if an employee refuses to fill out a Form W-4?

You withhold as if the employee checked Single or Married filing separately in Step 1(c) and made no entries in Steps 2, 3 or 4. That default usually results in higher withholding than a completed form.

Can an employee claim exempt on Form W-4?

Yes, if they had no federal income tax liability last year and expect none this year. The exemption covers federal income tax only, not Social Security or Medicare, and it must be renewed each year by February 15.

How long must employers keep Form W-4?

Keep withholding certificates with your employment tax records for at least 4 years, and keep them available for IRS review. State rules may require longer retention.

What to do next

1. Confirm your onboarding checklist requests the current-year Form W-4 and any required state certificate on day one.
2. Audit your files for missing or invalid forms and correct default withholding where needed.
3. Set a recurring early-February reminder for employees who claimed exempt and a hold on exempt status after February 15.
4. Write a lock-in letter procedure: who receives it, the 10 business day handoff and the effective date in payroll.
5. Check that your electronic W-4 system meets Publication 15-T requirements.
6. Fold these steps into your broader federal payroll compliance checklist.

Sources

• IRS: About Form W-4, Employee's Withholding Certificate
• IRS: Form W-4 (2026)
• IRS: Publication 15 (Circular E), Employer's Tax Guide
• IRS: Publication 15-T, Federal Income Tax Withholding Methods
• IRS: Withholding compliance questions and answers (lock-in letters)
• California EDD: DE 4, Employee's Withholding Allowance Certificate

Last reviewed: November 2026.