5 CFR § 352.705 - Return to Federal employment.
(a) Conditions. Reemployment rights may be exercised only under the following conditions. The individual must apply in writing to the former employing agency for reemployment not later than 30 calendar days after:
(2) Reversion of the function to Federal operation, whether reversion is through tribal or Federal action; or
(b) Termination. A former employee's entitlement to reemployment terminates for:
(3) Failure to accept, within 10 calendar days of receipt thereof, an offer of reemployment made under § 352.706 which is determined by the employing agency or by the Merit Systems Protection Board on appeal to be a proper offer of reemployment.