To enlist in the U.S. military you have to clear five sets of requirements: age, citizenship or residency, education, medical and physical fitness, and moral character. Federal law in Title 10 of the U.S. Code sets the floor, Department of Defense instructions fill in the detail, and each branch layers on its own standards that are usually tighter than the statutory minimums. Meeting the minimums makes you eligible to apply. It doesn’t guarantee a contract.
Age
The statutory minimum is seventeen, and anyone under eighteen needs written consent from a parent or legal guardian.1Office of the Law Revision Counsel. 10 USC 505 – Regular Components: Qualifications, Term, Grade The statutory ceiling is forty-two, but each branch sets its own upper limit for first-time enlistees with no prior service:
- Marine Corps: 28
- Army: 35
- Navy: 41
- Coast Guard: 41
- Air Force: 42
- Space Force: 42
Prior-service applicants sometimes qualify under different age rules depending on the branch and their previous experience.2USAGov. Requirements to Join the U.S. Military
Citizenship and Residency
You do not have to be a U.S. citizen. Under 10 U.S.C. § 504, you must be a U.S. national, a lawful permanent resident (green card holder), or a citizen of the Federated States of Micronesia, the Republic of the Marshall Islands, or Palau under those countries’ Compacts of Free Association.3U.S. Government Publishing Office. 10 USC 504 – Persons Not Qualified
There is a narrow exception. The Secretary of a military department can authorize enlistment for someone outside those categories if the person has a critical skill vital to the national interest. That authority is capped at 1,000 enlistments per military department per calendar year, and the applicant cannot begin training until all background investigations and security screenings are complete.3U.S. Government Publishing Office. 10 USC 504 – Persons Not Qualified
Non-citizens must also speak, read, and write English fluently.2USAGov. Requirements to Join the U.S. Military
Education and the ASVAB
Every branch requires at least a high school diploma or GED. A diploma opens far more slots. Each branch reserves a limited number of positions for GED holders, so applicants without a traditional diploma compete for fewer spots. Earning college credits or scoring higher on the entrance exam improves a GED holder’s odds.2USAGov. Requirements to Join the U.S. Military
Every applicant takes the Armed Services Vocational Aptitude Battery, or ASVAB. It produces an Armed Forces Qualification Test (AFQT) score that determines whether you’re eligible at all, and line scores that determine which jobs you qualify for. Minimum AFQT scores differ by branch. The Air Force, for example, requires a 31 for high school graduates and a 50 for GED holders.4U.S. Air Force. ASVAB Scoring well above the minimum opens more occupational specialties and gives a recruiter more to work with.
Medical and Physical Standards
The Department of Defense publishes its medical standards in DoDI 6130.03, which covers hundreds of conditions organized by body system.5Department of Defense. DoDI 6130.03 Volume 1 – Medical Standards for Military Service You take your physical at a Military Entrance Processing Station (MEPS), where doctors evaluate vision, hearing, joint range of motion, blood pressure, organ function, and mental health history. Conditions that commonly disqualify applicants include chronic diseases requiring ongoing treatment, severe allergies, asthma that persists past childhood, and mental health conditions such as major depression or ADHD treated with medication in recent years.
MEPS also runs a urinalysis drug screen. A positive result for marijuana typically suspends your application for at least 90 days. Positives for other substances often trigger a longer waiting period or permanent disqualification. A second positive result for any drug is almost always a permanent bar, and recruiters have no authority to waive it.
Height, weight, and body composition are measured against branch standards. If you exceed the maximum weight for your height and age, you go through a body fat measurement. Exceeding the body fat limit disqualifies you until you meet the standard. There is no waiver for being out of range at the time of processing.
Medical Waivers
A disqualifying condition does not automatically end the process. Each branch runs a medical waiver review that looks at whether the condition is stable, unlikely to worsen under military demands, and compatible with deployment. Approval is discretionary. When a branch needs more recruits, the threshold tends to loosen. When it has plenty of applicants, borderline conditions get denied more often. Your recruiter starts the paperwork, but the decision rests with medical and command authorities above the recruiting office.
Criminal History and Moral Character
Every applicant’s record gets screened against what the military calls moral character standards. The review looks at the nature, severity, and number of offenses.
A felony conviction is not an automatic lifetime bar, but it is a serious obstacle. Applicants with felony records can request a waiver, and approval depends on how long ago the offense occurred, evidence of rehabilitation, and the branch’s current needs. The most serious offenses, particularly sexual crimes and those requiring lifetime registration, are functionally impossible to waive.
Misdemeanors can also block enlistment depending on type and number. Multiple offenses of any kind, drug charges, and alcohol-related convictions all draw closer review. A pattern of minor offenses can be as disqualifying as a single serious one. Each branch handles waivers independently, so a denial from one service doesn’t prevent you from applying to another.
The Domestic Violence Bar
One category of criminal history sits outside the waiver system entirely. Under 18 U.S.C. § 922, anyone convicted of a misdemeanor crime of domestic violence is prohibited from possessing firearms or ammunition.6Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts Because military service requires carrying weapons, that firearms prohibition creates a permanent enlistment bar no branch can waive. It’s not a DoD regulation a recruiter can work around. It’s a federal criminal statute that applies to every person in the country. Applicants are sometimes caught off guard because the underlying conviction seemed minor at sentencing.
What You’re Signing
Once you clear every screening, you sign DD Form 4, the enlistment contract. It’s a binding agreement with the federal government that spells out your service obligation, branch, initial training dates, and any specific promises the military has made you, such as a job, bonus, or training slot. The form says plainly that anything a recruiter promised you that isn’t written on the form or its annexes is not enforceable.7Washington Headquarters Services. DD Form 4 – Enlistment/Reenlistment Document Verbal assurances about duty stations, deployments, or promotions mean nothing if they aren’t in the paperwork.
Signing also puts you within reach of the Uniform Code of Military Justice for fraudulent enlistment. If you concealed disqualifying information—undisclosed criminal history, hidden medical conditions, falsified education records—you can be prosecuted, with maximum punishment including a dishonorable discharge and confinement. That exposure doesn’t disappear once you’re in; fraud discovered years into service can still be charged.
The Eight-Year Obligation
Federal law requires every person who joins an armed force to serve for a total initial period of not less than six and not more than eight years. Current DoD policy sets that at eight years for all branches.8Office of the Law Revision Counsel. 10 USC 651 – Members: Required Service If you sign a four-year active-duty contract, the remaining four years are served in a reserve component, usually the Individual Ready Reserve. IRR members don’t drill or draw pay, but they can be recalled to active duty in a national emergency.
When your active-duty contract ends, the law requires you to be transferred to a reserve component to finish out the obligation, unless you reenlist or receive an earlier discharge for hardship.8Office of the Law Revision Counsel. 10 USC 651 – Members: Required Service A four-year enlistment is really an eight-year commitment with four of those years in a less active status.
The Delayed Entry Program
Most applicants don’t ship to basic training the day they sign. They enter the Delayed Entry Program (DEP), which allows up to 365 days between signing and reporting. During that time you are technically enlisted as a member of the Ready Reserve, but you don’t draw military pay, benefits, or housing.9Office of the Law Revision Counsel. 10 USC 513 – Enlistments: Delayed Entry Program The DEP period counts toward your eight-year total obligation.
Can you back out? In practice, yes. The contract obligates you to report, but the military has consistently separated people who refuse to ship rather than force them in. The separation is typically uncharacterized, meaning it does not appear as a negative discharge and hasn’t been known to affect employment, loans, or educational eligibility. Simply not showing up on your ship date is usually enough to trigger the separation process. Reporting to basic training and then trying to leave is a very different situation with potentially serious consequences, so the DEP window is the realistic off-ramp if you’ve changed your mind.