In the military, time in service is the running total of your creditable service measured from your Pay Entry Base Date (PEBD), and it drives three things: what you earn in base pay, when you can be promoted, and whether you qualify for a pension. Get the start date right and the rest of the system runs on autopilot. Get it wrong, and every raise and eligibility threshold slides with it.
Where the Clock Starts
Your PEBD is the date the military uses to compute creditable service for longevity pay and to place you on the correct column of the pay table.1Defense Finance and Accounting Service. Military Buy Back Field Definitions Total time in service is just today’s date minus your PEBD.
Two documents show it. Your DD Form 4 enlistment contract records the date of enlistment,2United States Military Entrance Processing Command. USMEPCOM Instructions in Accordance With DoDI 1304.02 and your Leave and Earnings Statement displays the PEBD in field 4.1Defense Finance and Accounting Service. Military Buy Back Field Definitions Check both early. An incorrect PEBD silently pushes back every pay raise and eligibility date that follows.
What Counts as Creditable Service
All periods of active duty count, including full-time National Guard duty performed under federal orders. Basic training and follow-on schools count from day one because they are performed in an active-duty pay status.3Office of the Law Revision Counsel. 37 USC 205 – Computation: Service Creditable
Breaks and the Delayed Entry Program
Gaps between enlistments don’t count. If you separate and later return, the civilian months in between drop out of your total. Time in the Delayed Entry Program is a common source of confusion. Federal law specifically excludes certain DEP periods from creditable service for reserve component members,3Office of the Law Revision Counsel. 37 USC 205 – Computation: Service Creditable and in practice the months you spent waiting for a training date after signing your contract almost never move your PEBD earlier.
Lost Time
Some absences extend your obligation instead of counting toward it. Enlisted members who desert, go AWOL for more than one day, or are confined in connection with a trial must make up that time after returning to full duty. The same applies if you can’t perform duties for more than a day because of drug or alcohol misuse or an injury from your own misconduct. If charges are later dismissed or a conviction is overturned, the Secretary of the relevant branch must waive the recoupment.4Office of the Law Revision Counsel. 10 USC 972 – Members: Effect of Time Lost
How Years of Service Raise Your Pay
Base pay is set by two variables: pay grade and years of service. Federal law ties basic pay entitlement directly to years of service computed under 37 U.S.C. ยง 205.5Office of the Law Revision Counsel. 37 USC 204 – Entitlement The pay table uses fixed longevity columns where raises kick in: under 2, 2, 3, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, and beyond, up to 40 years.6Defense Finance and Accounting Service. Military Pay Tables and Information Cross a threshold and the raise is automatic.
Longevity increases don’t run forever. The pay table extends to 40 years, but only for senior ranks: O-6 and above, W-4 and W-5, and E-8 and E-9. Everyone else flatlines at 26 years no matter how long they keep serving.6Defense Finance and Accounting Service. Military Pay Tables and Information
Promotion Eligibility
Time in service is a gate. You cannot cross into the next rank until you have enough of it, and the exact amount depends on which track you’re on.
Enlisted
Advancement to the lower enlisted grades is largely automatic once you meet time-in-service and time-in-grade minimums. Thresholds vary by branch, but six months of service for E-2 and 12 months for E-3 are common. Promotions to E-5 and above become competitive, weighing performance evaluations, board scores, and professional development on top of a service-time floor no one gets past without meeting.
Officers
Officer promotions run on statutory time-in-grade requirements. A second lieutenant or ensign cannot promote until completing 18 months in grade. A first lieutenant or lieutenant (junior grade) needs two years. Captains, majors, and lieutenant commanders each need three years in grade before a board can look at them. At the colonel and brigadier general level, the minimum drops to one year.7Office of the Law Revision Counsel. 10 USC 619 – Eligibility for Consideration for Promotion: Time-in-Grade and Other Requirements
High performers can be selected below the zone, ahead of their peer group. Federal law caps those early promotions at 10% of a competitive category’s total, with the Secretary of Defense authorized to raise the ceiling to 15% when the service needs it.8Office of the Law Revision Counsel. 10 USC 616 – Recommendations for Promotion by Selection Boards An officer considered below the zone but not selected does not incur a failure of selection, so there is no downside to being looked at early.
The 20-Year Retirement Threshold
Twenty years is the number that dominates career planning. Reaching it on active duty qualifies you for a pension. Falling short generally means no pension unless you qualify through a medical exception.
Active-Duty Retirement
Active-duty members with 20 or more years of service may apply for retirement. Officers face an additional requirement: at least 10 of those years must have been served as a commissioned officer, a rule that applies across the branches under parallel statutes.9Office of the Law Revision Counsel. 10 USC 7311 – Twenty Years or More: Regular or Reserve Commissioned Officers10Office of the Law Revision Counsel. 10 USC 8323 – Officers: 20 Years
Under the legacy High-3 system (members who entered before January 1, 2018, and did not opt into BRS), the pension equals 2.5% of the highest 36 months of basic pay times years of service. Retire at exactly 20 years and you get 50% of that average. Under the Blended Retirement System, the multiplier is 2.0%, so a 20-year BRS retiree gets 40%.11Office of the Law Revision Counsel. 10 USC 1409 – Retired Pay Multiplier BRS members trade that lower pension for TSP matching and a mid-career bonus, both described below.
Reserve and National Guard Retirement
Reserve component members still need 20 qualifying years, but retired pay does not start until age 60.12Office of the Law Revision Counsel. 10 USC 12731 – Age and Service Requirements A reservist who hits 20 qualifying years at 42 waits another 18 years for the first check.
One exception lowers that age. For each aggregate 90-day period of active duty served after January 28, 2008, the age-60 threshold drops by three months, though it can’t go below age 50.12Office of the Law Revision Counsel. 10 USC 12731 – Age and Service Requirements A reservist with multiple post-2008 deployments can start drawing pay years earlier than the standard age.
Medical Retirement Before 20 Years
A service member who is medically unable to continue serving can qualify for disability retirement without reaching 20 years. The disability must be rated at 30% or higher under the VA’s schedule of rating disabilities, it must be permanent and stable, and it must meet the statutory criteria on origin, such as being incurred in the line of duty.13Office of the Law Revision Counsel. 10 USC 1201 – Regulars and Members on Active Duty for More Than 30 Days If the rating is below 30% and you have fewer than 20 years, you receive a one-time disability severance payment instead of a lifetime pension. That line separates long-term security from a lump sum that runs out.
Time-in-Service Milestones Under the Blended Retirement System
Anyone who entered service on or after January 1, 2018, is automatically enrolled in BRS, and several benefits are tied to specific service-time marks.
TSP Contributions and Vesting
The Department of Defense automatically contributes 1% of your basic pay to your Thrift Savings Plan account starting 60 days after you enter active duty. After your second full year of service, DoD matches your voluntary contributions up to an additional 4%, for a combined government contribution of up to 5%. You are fully vested in those contributions after completing two years of service. Automatic and matching contributions continue through year 26.14MyAirForceBenefits. Blended Retirement System
If you’re past year two and not contributing at least 5% of your basic pay, you’re leaving the full match on the table.
Continuation Pay
BRS members become eligible for a one-time continuation pay bonus during a specific window. For calendar year 2026, you must have completed at least 7 but no more than 12 years of service measured from your PEBD.15MyArmyBenefits. Continuation Pay Taking the bonus commits you to a four-year additional service obligation that starts on the date you sign the election form and runs alongside any obligation you already have.16Army.mil. MILPER Message 25-329: Continuation Pay for Calendar Years 2025-2027 If your current enlistment ends before that four-year mark, you’ll need to reenlist or extend.
Fixing an Incorrect PEBD
An error in your PEBD delays raises, pushes back promotion eligibility, and can distort retirement calculations. Federal law gives you three years from the date you discover the error to file for a correction.17Office of the Law Revision Counsel. 10 USC 1552 – Correction of Military Records: Claims Incident Thereto The relevant records board can waive the deadline if it finds doing so serves the interest of justice, but a waiver is not something to plan around.
The form is DD Form 149, filed with the Board for Correction of Military Records (or Naval Records, depending on your branch).18Washington Headquarters Services. DD Form 149, Application for Correction of Military Record You must exhaust other administrative correction procedures first, and the burden of proof is on you. Gather your enlistment contract, prior LES records, and deployment orders before filing. Catching a discrepancy early is much easier than discovering it a year out from retirement.