As a prior service Marine joining the NG as a 12B, will I have to go through basic training or will I start in AIT? If so, how long is AIT?

Oh dude it’s easy. I know to reclass ton12b is just like 3 weeks. And I don’t think you have to go back through basic unless you’ve been out a long time. In my AIT portion we had a cat from the marine corps and he just had to fall in in the morning when we went to class but never had to do anything else with us.

Here is the current prior service guidance.


AR 601-210

Chapter 3
Enlistment in the Regular Army, U.S. Army Reserve, or Army National Guard for Prior
Service Applicants



AR 601-210, CHPT 7, 7-7
7–7. Basic training requirement
a. PS applicants who did not complete Army or Marine Corps BCT, or complete training for Air Force or Navy Special Operations Forces, or Air Force Security Police must attend Army BCT.
b. For RC only, applicants with no prior military service must complete at least 12 weeks of IADT and orders must reflect 12 weeks or until completion of training (10 USC 12103).









https://armypubs.army.mil/epubs/DR_pubs/DR_a/pdf/web/ARN6642_AR601-210_ADMIN_WEB_Final.pdf

It depends.... the longer you've been out the higher the odds you'll have to repeat basic. Your recruiter should be able to tell you for sure.