Code of Federal Regulations Title 5. Administrative Personnel § 5.870.507 Open enrollment periods

(c)(1) OPM sets the effective date for all insurance elected during an open enrollment period. The newly elected insurance is effective on the 1st day of the 1st pay period that begins on or after the OPM–established date and that follows a pay period during which the employee was in pay and duty status for at least 32 hours, unless OPM announces otherwise.

(2) A part-time employee must be in pay and duty status for one-half the regularly-scheduled tour of duty shown on his or her current Standard Form 50 for newly-elected coverage to become effective, unless OPM announces otherwise.

(3) An employee who has no regularly-scheduled tour of duty or who is employed on an intermittent basis must be in pay and duty status for one-half the hours customarily worked before newly-elected coverage can become effective, unless OPM announces otherwise. For the purpose of this paragraph, an employing office may determine the number of hours customarily worked by averaging the number of hours worked in the most recent calendar year quarter prior to the start of the open enrollment period.