According to the Department of Education's Federal Student Aid office, your 120 qualifying monthly payments do not need to be consecutive. For this reason, if you would like to go back to school and stop making PSLF qualifying monthly payments on your loans, you can certainly do so. In fact, when you return to school, your loans will automatically be placed in an 'in-school' deferment as long as you're enrolled at least half time.
Your loan servicer should notify you when entering this status. If you do not receive notification or your loans are not automatically deferred, you should contact your school's financial aid office. You may need to manually request the deferment for your account.
However, if you’re going to keep working full-time for a PSLF eligible employer throughout school, you can choose to make payments on your loans which will count toward PSLF. In order to do so, you'll need to request that your loans be taken out of their deferment period. You can make this request with your loan servicer directly, and it should be processed within a couple weeks. If the deferment is still showing on your account, you may need to follow up on request.
You'll resume making payments as usual and you can submit an Employment Certification Form (ECF) to ensure that your payments are being reflected accurately for forgiveness. Savi can assist with this process for borrowers enrolled in our Essential Plan. Please let us know if you have any questions or would like assistance by contacting support from within your Savi account.