OPM | Disability Retirement Info | If you have been separated from Federal service for more than 31 days
Article Excerpt: "...Your application for disability retirement must be received by OPM within one year after the date of your separation. If you have been separated from Federal service for more than 31 days, your former employing agency may no longer have your personnel records and may not be able to recover them in time to process your disability retirement application and submit it to OPM within the one-year time limit. If this is the case, you should submit your application directly to OPM rather than to your agency. ..."
Resource: www.opm.gov