29 C.F.R. § 825.202

(a) Definition. FMLA leave may be taken intermittently or on a reduced leave schedule under certain circumstances. Intermittent leave is FMLA leave taken in separate blocks of time due to a single qualifying reason. A reduced leave schedule is a leave schedule that reduces an employee's usual number of working hours per workweek, or hours per workday. A reduced leave schedule is a change in the employee's schedule for a period of time, normally from full-time to part-time.

(b) Medical necessity. For intermittent leave or leave on a reduced leave schedule taken because of one's own serious health condition, to care for a spouse, parent, son, or daughter with a serious health condition, or to care for a covered servicemember with a serious injury or illness, there must be a medical need for leave and it must be that such medical need can be best accommodated through an intermittent or reduced leave schedule. The treatment regimen and other information described in the certification of a serious health condition and in the certification of a serious injury or illness, if required by the employer, addresses the medical necessity of intermittent leave or leave on a reduced leave schedule. See §§ 825.306, 825.310. Leave may be taken intermittently or on a reduced leave schedule when medically necessary for planned and/or unanticipated medical treatment of a serious health condition or of a covered servicemember's serious injury or illness, or for recovery from treatment or recovery from a serious health condition or a covered servicemember's serious injury or illness. It may also be taken to provide care or psychological comfort to a covered family member with a serious health condition or a covered servicemember with a serious injury or illness.

(1) Intermittent leave may be taken for a serious health condition of a spouse, parent, son, or daughter, for the employee's own serious health condition, or a serious injury or illness of a covered servicemember which requires treatment by a health care provider periodically, rather than for one continuous period of time, and may include leave of periods from an hour or more to several weeks. Examples of intermittent leave would include leave taken on an occasional basis for medical appointments, or leave taken several days at a time spread over a period of six months, such as for chemotherapy. A pregnant employee may take leave intermittently for prenatal examinations or for her own condition, such as for periods of severe morning sickness. An example of an employee taking leave on a reduced leave schedule is an employee who is recovering from a serious health condition and is not strong enough to work a full-time schedule.

(2) Intermittent or reduced schedule leave may be taken for absences where the employee or family member is incapacitated or unable to perform the essential functions of the position because of a chronic serious health condition or a serious injury or illness of a covered servicemember, even if he or she does not receive treatment by a health care provider. See §§ 825.113 and 825.127.

(c) Birth or placement. When leave is taken after the birth of a healthy child or placement of a healthy child for adoption or foster care, an employee may take leave intermittently or on a reduced leave schedule only if the employer agrees. Such a schedule reduction might occur, for example, where an employee, with the employer's agreement, works part-time after the birth of a child, or takes leave in several segments. The employer's agreement is not required, however, for leave during which the expectant mother has a serious health condition in connection with the birth of her child or if the newborn child has a serious health condition. See § 825.204 for rules governing transfer to an alternative position that better accommodates intermittent leave. See also § 825.120 (pregnancy) and § 825.121 (adoption and foster care).

(d) Qualifying exigency. Leave due to a qualifying exigency may be taken on an intermittent or reduced leave schedule basis.