Employers are required to obtain a signed IRS Form W-4 when hiring a new employee. Although Form W-4 is revised each year by the IRS to reflect current tax rates, exemption amounts, etc., the form remains valid until an employee provides a new form. In other words, there is no requirement to obtain a new form each year.

The IRS “encourages” employers to remind employees to review the form and adjust their exemptions if the employee has a significant tax overpayment or underpayment on his or her prior year tax return.