How to ask student for more information in order to grant makeup final A student of mine has asked to take his final early because he is "going out of town." He has only just mentioned this to me and we are already halfway through the quarter.

I have spoken with some faculty in my department and one has suggested that if not taking the exam early would impose an undue financial burden (i.e. he bought tickets months ago and didn't know he would have a final this day) then he should be allowed to take the exam early, but if he planned a road trip with his friends last week, for example, then he should have to take the exam at the scheduled time.

I like this policy, so my question at the moment is: how can I ask this student for more information about his vacation? It certainly seems as if it will be the latter since he has not mentioned it to me until now, but I would like to be sure before I decide.

Additional comments: I would obviously rather him not take the exam on an earlier date because I am worried he might share test information with other students. This is a calculus final so it takes effort on my part to write a different exam,  and I feel a bit miffed at having to write an entire new test so someone can go on vacation.

Edit: The syllabus statement on makeup exams: "In this course, we will have one midterm and a final exam on the dates mentioned above. These dates are firm and cannot be changed except under extraordinary circumstances. Make-up exams will be permitted at my discretion.'
Unless this is a very urgent trip, then there's no way I'd allow the change.  There are always students who want to play "airfare wars."  They buy airline tickets for a date half-way through finals, knowing full well they might have an exam scheduled late.  They think that coming to me and showing me their ticket, "But I already spent $480 on tickets!"  will leverage compliance from me.  The best they'll get from me for their manipulation is that I'll give them an incomplete and give them their final MUCH later (so they have to retain their fresh knowledge a couple months.)  

If his sister is getting married or the Army Reserves has called him up or is mother is hit by a bus, then OK, I'm happy to accommodate.  But I didn't take "But I have plans" from my own children as an excuse.

I'll mention here that my syllabus contains a sentence that says plainly that I won't budge just because you already bought your ticket.

To your specific question, I'd say to, or e-mail the student and say something like, "Unless this is a crisis, then I can't move the date of your exam."  Then it's up to him to convince you that it's a crisis.