5 CFR § 838.441
Computing lengths of service
November 4, 2020
(a) The smallest unit of time that OPM will calculate in computing a formula in a court order is a month, even where the court order directs OPM to make a more precise calculation.
(b) If the court order states a formula using a specified simple or decimal fraction other than twelfth parts of a year, OPM will use the specified number to perform simple mathematical computations.