31 C.F.R. § 29.352
For any given pay period, employee contributions are considered to have been made before the freeze date if the pay date was on or before June 30, 1997. As a result, for calendar year 1997, Treasury will fund refunds of employee contributions made by teachers through pay period 12 and fund refunds of employee contributions made by police officers and firefighters through pay period 13. If pay period records are unavailable for calendar year 1997, and the participant separated on or before June 30, 1997, Treasury will fund 100 percent of the refund of retirement contributions. If pay period records are unavailable for calendar year 1997, and the participant was hired before January 1, 1997, and separated after December 31, 1997, Treasury will fund 50 percent of the refund of retirement contributions made to teachers in calendar year 1997, and 48 percent of the retirement contributions made to police officers or firefighters in calendar year 1997. Otherwise, if the participant separated after June 30, 1997, the percent of contributions made in calendar year 1997 funded by Treasury is assumed to be the ratio where the numerator is the number of days before July 1 the participant was employed in calendar year 1997 and the denominator is the number of days the participant was employed in calendar year 1997.
31 C.F.R. § 29.352