The FMLA’s treatment of overtime depends on whether the overtime is mandatory or voluntary. Section 825.205(c) of the FMLA regulations provides that if an employee would normally be required to work overtime but is unable to do so because of a FMLA-qualifying reason, the hours which the employee would have been required to work may be counted against the employee’s FMLA entitlement. Voluntary overtime hours that an employee does not work due to an FMLA-qualifying reason may not be counted against the employee’s FMLA leave entitlement.

An employee may also be entitled to a reasonable accommodation under the ADA (assuming the employee has an ADA disability). Whether an accommodation excusing an employee from working overtime is reasonable requires an individualized assessment based on the specific facts, including whether working overtime is an essential job function.