It’s in your best interest to make sure that you get credit for your CSRS and FERS employment, plus any active duty military service. However, it may surprise you to learn that there are other kinds of employment for which you can get credit and that can be used in the computation of your annuity.
What those are is spelled out at 5 U.S. Code 8332. Among them are substitute carrier work for the post office, service with Peace Corps and Vista, volunteer service under the Economic Opportunity Act of 1964, and employment as a United States Capital Guide. While some of these periods of service are creditable only within specific time periods, others are not.
Once you have a clearer picture of which parts of your work history might be creditable, go to your personnel office and ask to see your Official Personnel Folder (OPF). That way you can make sure it contains every bit of service for which you can get credit. If something is missing, you’ll want to make sure that it’s added. However, if no retirement deductions were taken from your pay for that additional service, you may need to make a deposit to the Civil Service Disability and Retirement Fund. Your personnel office can tell you how to do that.
You can also get credit for employment covered by another federal retirement system, such as TVA or the Foreign Service, as long as you aren’t receiving any retirement benefits for that time under the other system. To get credit for that period of employment, you’ll have to get a refund of your contributions and deposit it, with interest, in the Fund.
A word to the wise. Get your federal service record in order now. Don’t put it off until you’re ready to retire. Waiting until the last minute can not only keep you from getting credit for some service but can also delay your first annuity payment until your work history is sorted out. And these days, with processing times being what they are, that delay might be a long, long one.