What Is an Active Duty Service Date?

The United States military, like all career fields, has its own language. If you are unfamiliar with military life and are on a military base listening to military-speak, you might feel as if you're in a foreign country. But, upon joining the military, it doesn't take long to learn the jargon, because you will be completely immersed in it. One of the first terms you might start with is your active duty service date.

According to the Department of Defense Dictionary of Military and Associated Terms, active duty refers to "full-time duty in the active military service of the United States," including full-time National Guard duty. When you join any branch of the military and are actively serving, you are considered on active duty.

The military has many different service dates, and a person can have different service dates for different purposes. Generally speaking, your active duty service date is the date of your original entry into the military. That date may be modified, however, if you've had any breaks in service. For example, if you were enlisted, left the military to go to college, then rejoined as an officer, your active duty service date will change. It might also be modified if you receive a commission upon graduation from college but don't enter active duty until some months later.

DIEUS is the date of initial entry into the uniformed services. The uniformed services include the Air Force, Army, Navy, Marine Corps, Coast Guard, National Oceanic and Atmospheric Administration, and the Public Health Service. This is service from the date of initial acceptance of enlistment, commission, or appointment. This date is fixed, regardless of breaks in service or time lost. For example, the date you accept a commission, perhaps on graduation from college, would be your DIEUS, regardless of when you actually began on active duty.

This is the total active federal military service date and, according to Air Force Instruction 36-2604, includes "all periods of active Federal military service in commissioned, warrant, flight officer, or enlisted status." However, this date is adjusted for breaks in service. If you enlisted for four years, left the military and went to college for four years and then were commissioned, your TAFMSD would be adjusted to be four years later than the original date you went on active duty.

Service dates stay with you upon your exit from the military if you become a civilian employee of the government. All federal employees have a service computation date that determines how much government service is credited toward eligibility for a benefit or entitlement, for example annual leave or retirement. According to Tammy Flanagan of the National Institute of Transition Planning, the SCD "establishes a 'virtual' starting date for continuous creditable service." Time in federal service, including military time and not including any breaks in service, is computed and added to your start date, so that your SCD may be several years before the actual date you began as a civilian federal employee.