As an F-1 student, you are granted permission to stay in the United States for “Duration of Status” (D/S), which means that you are allow to remain in the country until the expiration date on your form I-20 or the completion of your program of study, whichever comes first, plus an additional 60-day grace period.
You must apply for an extension in order to remain in lawful status if you are not going to be able to finish your studies by the date noted in Item 5 of your form I-20. The application for extension of program must be submitted to the Office of International Services no later than 30 days prior to the end date on your current I-20.
Note: Only compelling academic or medical reasons, such as changes of major or research topics, unexpected research problems and documented illness, can justify an extension of stay. Delays caused by academic probation or suspension are not acceptable reasons for a program extension.