§ 825.305 Certification, general rule.
(a) General. An employer may require that an employee's leave to care for the employee's covered family member with a serious health condition, or due to the employee's own serious health condition that makes the employee unable to perform one or more of the essential functions of the employee's position, be supported by a certification issued by the health care provider of the employee or the employee's family member. An employer may also require that an employee's leave because of a qualifying exigency or to care for a covered servicemember with a serious injury or illness be supported by a certification, as described in §§ 825.309 and 825.310, respectively. An employer must give notice of a requirement for certification each time a certification is required; such notice must be written notice whenever required by § 825.300(c). An employer's oral request to an employee to furnish any subsequent certification is sufficient.
(b) Timing. In most cases, the employer should request that an employee furnish certification at the time the employee gives notice of the need for leave or within five business days thereafter, or, in the case of unforeseen leave, within five business days after the leave commences. The employer may request certification at some later date if the employer later has reason to question the appropriateness of the leave or its duration. The employee must provide the requested certification to the employer within 15 calendar days after the employer's request, unless it is not practicable under the particular circumstances to do so despite the employee's diligent, good faith efforts or the employer provides more than 15 calendar days to return the requested certification.