You will have to submit VA Form 22-1990, but make your election date to start your Post 9/11 GI Bill after you run out of Chapter 30 benefits. If you submit it with benefits left, you won’t get the additional 12 months of benefits – you will get just what you have left under the MGIB –not good.
Once you submit the paperwork, you will get a new Certificate of Eligibility sent to you. One thing you will notice is the number of months and days you have left will be less than the 12 months you expected and here is why. The VA will continue paying you benefits through the semester, but they are not “free”. The VA will deduct whatever months and days you were in school after your MGIB benefits ended from your additional year of Post 9/11 GI Bill benefits.
At the time, you may think you are getting the rest of the semester after your 20 days ran out for nothing, but there is a cost involved. However, the important part is it is a seamless transition from one GI Bill to the other and your pay continues on as long as you remain in school and have benefits left, regardless if it is under Chapter 30 or 33.