If a patron changes patron types in the middle of a checkout period, the original loan period at the time of checkout applies to the item, even for subsequent renewals, until its return.
For example, Joe checks out a book while an undergraduate student and his loan period is 30 days. If Joe becomes a graduate student after initially checking out the book, the loan period remains 30 days for his renewals, not 90 days, which is the loan period for graduate students. If Joe as a graduate student wishes to have the item's loan period set for 90 days, along with any renewals, then he will have to visit the Circulation Desk with the book in question and have it rechecked out to his account.
Additionally any other policies relating to the initial checkout loan period applies until the item is returned; this includes fine rates.