5 CFR § 351.805 - New notice required.
(b) An agency must give an employee an amended written notice if the reduction in force is changed to a later date. A reduction in force action taken after the date specified in the notice given to the employee is not invalid for that reason, except when it is challenged by a higher-standing employee in the competitive level who is reached out of order for a reduction in force action as a result of the change in dates.
(c) An agency must give an employee an amended written notice and allow the employee to decide whether to accept a better offer of assignment under subpart G of this part that becomes available before or on the effective date of the reduction in force. The agency must give the employee the amended notice regardless of whether the employee has accepted or rejected a previous offer of assignment, provided that the employee has not voluntarily separated from his or her official position.