Your loan technically goes into «default» after not making a payment on the loan for 270 days. (thecollegeinvestor.com)
A common issue here is when one party takes ownership of the asset, such as a vehicle, but stops making payments on the loan while your name is still attached. (creditabsolute.com)
You'll need to work with your loan servicer to apply for deferment or forbearance; and be sure to keep making payments on your loan until the deferment or forbearance is in place. (studentaid.ed.gov)