Although you are admitted to the U.S. for "duration of status," you must still be attempting to complete your studies by the expiration date on you I-20 (item 5 on page 1 of the I-20). This date is an expected date of completion. Under certain circumstances you may have the date extended. The delay must be caused by compelling academic or medical reasons, such as changes of major or research topics, unexpected research problems, or documented illnesses. Please note that delays caused by academic probation or suspension are not acceptable reasons for a program extension. The application for extension may be made at any time before your I-20 expires. Failure to apply for a program extension before the expiration date will mean you have violated U.S. government requirements and you will have to apply for reinstatement.