Caution:

If, in a year before 2020, you received a lock-in letter for an employee, then for 2026 you should continue to follow the instructions in the lock-in letter. You will use the withholding methods described in Pub. 15-T for an employee with a Form W-4 from 2019 or earlier, or you may use the optional computational bridge to treat 2019 and earlier Forms W-4 as if they were 2020 or later Forms W-4 for purposes of figuring federal income tax withholding. See How To Treat 2019 and Earlier Forms W-4 as if They Were 2020 or Later Forms W-4 under Introduction in Pub. 15-T. You should continue following the instructions in the pre-2020 lock-in letter until you receive a letter releasing your employee from the lock-in procedures, you receive a modification notice, or your employee gives you a new Form W-4 that results in more withholding than would result under the notice.

For additional information about employer withholding compliance, see IRS.gov/WHC .

Substitute Forms W-4.

You’re encouraged to have your employees use the official version of Form W-4. You may use a substitute version of Form W-4 to meet your business needs. However, your substitute Form W-4 must contain language that is identical to the official Form W-4 and your form must meet all current IRS rules for substitute forms. At the time you provide your substitute form to the employee, you must provide them with all tables, instructions, and worksheets from the current Form W-4. For more information, see Pub. 15-T.

You can’t accept substitute Forms W-4 developed by employees. An employee who submits an employee-developed substitute Form W-4 after October 10, 2007, will be treated as failing to furnish a Form W-4. However, continue to honor any valid employee-developed Forms W-4 you accepted before October 11, 2007.

Invalid Forms W-4.

Any unauthorized change or addition to Form W-4 makes it invalid. This includes taking out any language by which the employee certifies the form is correct. A Form W-4 is also invalid if, by the date an employee gives it to you, they clearly indicate it is false. An employee who submits a false Form W-4 may be subject to a $500 penalty. You may treat a Form W-4 as invalid if the employee wrote “exempt” below Step 4(c) and checked the box in Step 2(c) or entered numbers for Steps 3 and 4.

When you get an invalid Form W-4, don’t use it to figure federal income tax withholding. Tell the employee it is invalid and ask for another one. If the employee doesn’t give you a valid one, and you have an earlier Form W-4 for this employee that is valid, withhold as you did before. If you don’t have an earlier Form W-4 that is valid, withhold tax as if the employee had checked the box for Single or Married filing separately in Step 1(c) and made no entries in Step 2, Step 3, or Step 4 of the 2026 Form W-4. However, an employee who was paid wages in 2019 who never submitted a valid Form W-4 and submits an invalid Form W-4 in 2026 should continue to be treated as single and claiming zero allowances on a 2019 Form W-4. If you use the optional computational bridge, described earlier under Redesigned Form W-4 , you may treat this employee as if they had checked the box for Single or Married filing separately in Step 1(c), and made no entries in Step 2 and Step 3, an entry of $8,600 in Step 4(a), and an entry of zero in Step 4(b) of the 2026 Form W-4.

Amounts exempt from levy on wages, salary, and other income.

If you receive a Notice of Levy on Wages, Salary, and Other Income (a notice in the Form 668 series), you must withhold amounts as described in the instructions for these forms. Pub. 1494 has tables to figure the amount exempt from levy. If a levy issued in a prior year is still in effect and the taxpayer submits a new Statement of Exemptions and Filing Status, use the current year Pub. 1494 to figure the exempt amount.