Registration related deadlines including tuition payment for added classes and the undergraduate add-drop period are extended to Monday, Sept. 17, UT spokesperson Gary Susswein said in an email.
The deadlines were originally Friday, but because of the evacuation of buildings campus-wide and the University's decision to cancel classes Friday, the deadline was pushed back. Campus buildings were evacuated because of a bomb threat made against campus Friday morning.
Along with payment for added classes and undergraduate add-drop, Friday was also the deadline for graduate students to add a class and for law students to add or drop a class with the dean's approval. It is also the last day to drop a class and still have the opportunity to receive a refund. The University pushed back these deadlines also.
September 4 was the last day of official add-drop for undergraduate students. After this date, the registrar's calendar says "changes in registration may require the approval of the department chair and usually the student’s dean."