Though the oldest that anyone can be drafted into the Army is 26, different rules exist for the maximum age that it takes to go into service. The reason for a maximum age is twofold. First, the military wants people who are as able-bodied as possible to complete the tasks that are required in many of the positions, particularly those that are entry-level. Second, they are hoping to have a long-term commitment from many of the enlistees, and because of this, they want people who are young, and not people who are almost at retirement age, or even halfway there. In 2011, the Army briefly made that age limit 42, but when it became clear that political forces were not going to need to institute a draft or broaden the need for military forces, they removed that cap and pulled it back. Though a federal cap of 42 for any military branch still exists, all of the branches have more strict guidelines than this.

1. If you have never served in any branch of the military, then the maximum age that you can enlist in the Army is 35. This is also the case for people who are interested in joining the army reserves, as the original boot camp training and the physical requirements for both versions of the service are the same. This means that the paperwork must be finished, the medical exam completed, and you are on the bus on your way to basic training before you reach your 35th birthday, not your 36th.

2. If you served in a different branch of the military, and either want to make a change to a different one, or to reenlist after taking some time off, the requirements are different. Because you have already been trained out of rookie status, you are of more value to the military and may no longer need a physically active job before they place you in higher ranks. Also, it is unlikely that you will be taken to boot camp, and you will therefore not be compared directly with other new recruits, but evaluated on your own merits as an asset to the Army. If you are interested in re-entering the Army or Army Reserve, or switching from another branch of the military, the maxiumum age is 59.

3. Finally, there are few exceptions to this rule. Most of the waivers that exist happened because someone was scheduled before a certain age, but was slowed in some way by a glitch in the paperwork. Even then, waivers on age are very difficult to obtain, and usually require that the enlistee has a skill that the Army desperately needs.