Interest starts accruing on your unsubsidized federal or private student loans as soon as the loans have been disbursed. So, while you don't need to make payments while in school, interest will keep accumulating until you start making payments. Once that period starts, the lender will add the accrued interest to your balance.[1] One exception to this rule is if you have federal subsidized loans. In this case, interest still accrues, but the federal government pays it for you.[1]