Re-enlisting into the Marine Corps is an entirely different process than joining as a new recruit. For those already in the service, re-enlistment can signal the beginning of a career in the Marine Corps rather than just a stint of service. For those who have already left the service, it can be a way to get back in after taking a short break. Either way, Marines who are re-enlisting into the service must meet specific requirements to be eligible.
Perhaps the most important aspect of re-enlistment for Marines is their record of prior service. Upon the expiration of their enlistment contract, Marines are assigned a re-enlistment code. This code is, in essence, a grade of their performance while in the service. To re-enlist, Marines must have a re-enlistment code of either RE-1A or RE-1B. Codes other than this generally disqualify a Marine for re-enlistment for various reasons, ranging from humanitarian or personal hardship to a failure to meet disciplinary standards. Marines with re-enlistment codes other than RE-1A or RE-1B can still attempt to re-enlist with a waiver or by meeting certain criteria; however, it can pose a significant hurdle in the process.
Marines with prior service looking to re-enlist are subject to different age requirements than new recruits. To re-enlist, Marines must have a "constructive" age of under 32. Calculating a Marine's constructive age involves subtracting their years of service from their actual age. For example, a 42-year-old enlisted Marine with 15 years of service in the Marine Corps would have a constructive age of 27 and, therefore, still be eligible to re-enlist.
Although they have already enlisted and met most of the basic standards, Marines interested in re-enlistment must still meet the basic criteria for new recruits joining the service. This includes all age and educational requirements, which should be no issue considering prior service Marines need to meet these requirements to enlist in the first place. However, Marines should still be medically sound for duty and should be free of major law violations and alcohol or drug-related offenses.
In some cases, Marines looking to re-enlist directly after the expiration of their contract and continue in the USMC may not be able to despite meeting all of the requirements. This is because the Marine Corps only has a certain number of spots, or "boatspaces," for re-enlistees in each career field. If there are too few boatspaces for all Marines trying to re-enlist in a certain career field, those who are not selected for re-enlistment must separate from the service. If there are too many boatspaces, on the other hand, the USMC will often times offer re-enlistment bonuses to qualified Marines. In either case, once Marines successfully re-enlist without a break-in-service, they are classified as a career Marine and are not required to compete for subsequent re-enlistments.