Customs and Border Protection (CBP) officers make the final decision to allow or deny your entry to the United States. If you are not carrying the correct, original documents at the Port of Entry or if you did not pay the SEVIS I-901 fee when you received your initial I-20, you may be denied entry or only granted temporary entry for 30-days (Form I-515A).
If you receive a Form I-515A, you must contact International Student Services (ISS) to meet with an international student advisor as soon as possible. You will have 30 days from the date you entered the U.S. to send the required documents to the Student and Exchange Visitor Program (SEVP) to satisfy the Form I-515A. If you fail to respond in a timely manner, your SEVIS record may be terminated.
Read more at Study in the States: What is Form I-515A?