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You can do everything right when bringing on a new employee, offer competitive pay, create a strong onboarding experience, set clear expectations, and still make a costly mistake before their first paycheck is ever issued.
In many cases, the issue comes down to one simple document: Form W-4.
If you currently have employees or are preparing to hire your first, this is something you need to fully understand. Not because it is overly complex, but because it directly impacts your compliance as an employer and your employees’ tax situation.
What Form W-4 Actually Does
When you hire an employee, you are required to have them complete Form W-4, also known as the Employee’s Withholding Certificate.
This form determines how much federal income tax you must withhold from their paycheck. It includes details such as:
- Filing status
- Multiple job adjustments
- Tax credits
- Additional income
- Deductions
- Any extra withholding amount requested
It is important to recognize that you do not make these decisions; the employee does. Your responsibility is to apply withholding based strictly on the information they provide.
If an employee fails to submit a completed W-4, the IRS requires you to default to withholding as if they are single or married filing separately, with no adjustments. While this may result in higher withholding than necessary, it protects you from the risk of under-withholding.
The key takeaway is simple: no completed W-4 means you must follow the IRS default method.
When an Employee Claims “Exempt”
You may encounter a situation where an employee claims they are exempt from federal income tax withholding.
This is allowed, but only under very specific conditions:
- They had no federal income tax liability in the previous year
- They expect to have no federal income tax liability in the current year
If both conditions are met and the employee properly claims exempt status, you do not withhold federal income tax from their wages.
However, there is an important limitation: exempt status is only valid for one calendar year.
If the employee wishes to remain exempt, they must submit a new Form W-4 claiming exempt status by February 15 of the following year.
If they fail to do so, you are required to begin withholding taxes using the default method. If they submit a new exempt form after February 15, you may apply it going forward, but you are not permitted to refund any taxes already withheld during the period when the exemption was not in effect.
Understanding IRS Lock-In Letters
Another important scenario to be aware of is the IRS lock-in letter.
If the IRS determines that an employee is not having enough tax withheld, they may issue a notice directing you to withhold a specific amount for that employee.
Once a lock-in letter is issued, you are required to follow it exactly.
Even if the employee submits a new Form W-4 that would reduce their withholding, you must disregard it unless the IRS formally releases the restriction.
You are, however, required to accept any new W-4 that increases withholding above the mandated amount.
If the employee disagrees with the IRS determination, they must resolve it directly with the IRS. You cannot make adjustments based solely on the employee’s request.
Additionally, if the employee leaves and is rehired within 12 months, the lock-in requirements still apply.
Why This Matters for Your Business
Form W-4 may seem like routine paperwork, but handling it incorrectly can create significant issues.
Improper withholding can lead to unexpected tax liabilities for your employee and potential compliance problems for your business. The IRS cross-checks withholding through Forms W-2, and patterns of under-withholding will eventually be identified.
Your responsibilities as an employer are straightforward:
- Collect a properly completed Form W-4 at the time of hire
- Apply withholding exactly as indicated
- Monitor exempt status renewals by February 15
- Follow any IRS lock-in instructions without exception
When you understand and follow these steps, payroll becomes far more manageable and far less stressful.
Final Thoughts
You started your business to create value, serve clients, and build something meaningful. Payroll compliance may not be the most exciting part of that journey, but it is essential to maintaining a stable and sustainable operation.
Handling Form W-4 correctly protects your business, supports your employees, and gives you confidence that your processes are running as they should.
And that level of confidence is invaluable.
