Interest continues to accrue (be charged) on a student loan even when the student loan borrower isn't making payments on the loan. So, if the student loan borrower is in a deferment or forbearance interest can still rack up.

Does accrued interest stop?

Your interest will continue to accrue (grow) while your loans are deferred, and at the end of the deferment, any Unpaid Interest will capitalize (be added to your loan's Current Principal). ... If you can pay your accrued interest before it capitalizes, that can help keep your Total Loan Cost down.

Does interest accrue over time?

If you're on a payment plan or have deferred payments, interest continues to accrue. This amount is added to your principal, increasing your student loan balance. If you're able, it can make sense to pay at least the interest each month.