Transferring from the active duty military to the Guard at the end of your service commitment is a simple process. However, while it is possible to end your active duty service commitment early and transfer to the Guard, it can be difficult, especially during wartime. Most Commanders are loathe to release their personnel to the Guard when so many active duty units are overtaxed. There are programs that allow for transfers to the National Guard.
Contact a recruiter for the Army or Air National Guard unit you wish to join. The recruiter will help you handle the paperwork and find an opening in the unit for you.
Contact the Unit Career Counselor or Personnel Department at your current active duty unit if you are trying to end your active duty service commitment early. They will be able to advise you as to your options for leaving active duty and joining the Guard.
Request an early release from your active duty service component if you are still serving on active duty. Once this is approved by your Commander, you can join the Guard.
Out-process your current unit. You must turn in all gear issued to you and fill out any necessary paperwork. You'll also receive your DD Form 214 - Discharge Paper. This document is as important as your birth certificate, so keep it in a safe place.
Join the Army or Air Guard unit of your choice. Your recruiter will process you into the unit, and an officer from the unit will swear you in.