An employee or Member who is eligible for retirement must file a retirement application with his or her agency. A former employee or Member who is eligible for retirement must file a retirement application with OPM. The application should not be filed more than 60 days before becoming eligible for benefits. If the application is for disability retirement, the applicant and the employing agency should refer to subpart L of this part. If the application is for phased retirement status, the employee and the employing agency should refer to subpart Q of this part.
5 C.F.R. §831.501