If an employee has more than one job, they may claim exemptions only with their principal employer.   Employees must report the above-listed information on a Form M-4 - Employee's Withholding Exemption Certificate and claim the proper number of exemptions. Employees can change the number of their exemptions on Form M-4 by filing a new certificate at any time if the number of exemptions increases. If the number of exemptions decreases, they need to file a new certificate within 10 days.