A claim may be allowed under this subchapter only if application is filed with the Office before the employee or Member is separated from the service or within 1 year thereafter. This time limitation may be waived by the Office for an employee or Member who, at the date of separation from service or within 1 year thereafter, is mentally incompetent if the application is filed with the Office within 1 year from the date of restoration of the employee or Member to competency or the appointment of a fiduciary, whichever is earlier.