W-4 form: what the employer does with it, and what it cannot do

The W-4 form — Employee’s Withholding Certificate — is how an employee in the United States tells their employer how much federal income tax to withhold from their pay. The employee completes it, the employer applies it, and payroll withholds accordingly from the next practicable pay period.

It is worth being precise about the roles, because this is where employers get into difficulty. The W-4 is a declaration by the employee. The employer’s obligation is to obtain it, apply it and retain it — not to check whether the employee filled it in sensibly, and certainly not to tell them what to put.

What the employer must do with a W-4 form

• Obtain one from every new employee before the first payroll, or withhold as a single filer with no adjustments until one is provided.
• Apply the current certificate from the next practicable pay period after receiving it.
• Keep it on file for the retention period applicable to employment tax records, and be able to produce it.
• Apply a replacement W-4 when the employee submits one — they may change it whenever their circumstances change.
• Use the current year’s edition; the form has been substantially redesigned since the allowances era.

The redesign matters for anyone whose payroll process still refers to allowances. The modern form asks about multiple jobs, dependants, other income and deductions rather than a number of allowances, and payroll software configured against the old model produces wrong withholding rather than an error message.

What the employer must not do

Do not advise employees how to complete it. An employer that suggests entries takes on a role it is not licensed for and cannot defend if the employee is later under-withheld. Point at the IRS estimator and the instructions on the form, and answer process questions — deadlines, where to send it, when it takes effect — rather than tax questions.

Do not accept an altered form, and do not act on a verbal instruction to change withholding. The certificate is the instruction; a message asking for "a bit more tax taken out" without a new W-4 leaves nothing on file to show why the change was made.

A W-4 is not a W-9 and not an I-9. The W-4 sets withholding for an employee. The W-9 collects a taxpayer identification number from a contractor or vendor. The I-9 verifies work authorisation. Three forms, three purposes, collected at roughly the same moment — which is exactly why they get confused.

Collecting it without chasing it

1. Include the current W-4 in the onboarding pack rather than sending it separately.
2. Let the employee complete it electronically and sign it, instead of printing and scanning.
3. Check it is signed and dated — an unsigned certificate is not valid.
4. File it with the employee record, not in the payroll inbox.
5. Refresh the edition in your pack every January, and review anyone still on a pre-redesign certificate.

Because the W-4 is a fillable federal PDF that has to be completed, signed and kept unchanged, it is easier to handle as a form than as an attachment. Ettex PDF lets the employee fill and sign the current edition in place and returns a flattened copy for the file, so what is retained is what was signed. Fitting that into the employee onboarding checklist alongside the I-9 removes most of the chasing.