The service computation date is the date on which you start counting the years of service you need to retire.
The date for most employees is the date on which they first enter the service. However, some have been on active duty with the armed forces and may be entitled to service credit for that time. If you are one of them and were employed before October 1, 1982, you’ll automatically get credit for it in determining your eligibility to retire. As a result, your date will be moved back to an earlier date to reflect that period of service. On the other hand, if you were employed on or after October 1, 1982, you won’t get any credit for it unless you make a deposit. If you do, your date will be adjusted accordingly.
If you ever left government and then returned, the time between those two periods of employment won’t count. As a result, your date would be moved forward so that the new date would only include the time that you were actually employed. The same is true if you took leave without pay that exceeded six months in a calendar year. Your date would be moved forward the exact number of days, weeks or months needed to create a seamless service credit history.
No matter what you situation is, all you have to do to determine when you will have enough years of service to retire is to start with your service computation date and move forward on the calendar until you have the right combination of service and age.