India, Sept. 13 -- A major change to US student visa rules takes effect on September 15, ending the long-standing "duration of status" system for most F-1 and J-1 students and replacing it with a fixed period of admission.

With the deadline approaching, Harvard, Brown, Columbia, Yale, Stanford and other universities have issued guidance urging international students to understand how the new system could affect travel, program extensions and post-study plans.

The US Department of Homeland Security's final rule says the change will replace duration-of-status admission with a fixed period, generally capped at four years or the length of the program, whichever is shorter. Students who need additional time will have to seek an extension of ...