Posted 16 April 2012 - 04:18 PM
When you decline an offer, you are giving up your interest in the program and thus allow the school to offer the spot to someone else. However, when you accept an offer, there is no legal obligation to actually attend that school. You won't be forced to pay tuition, or anything like that -- you will lose whatever deposits you have paid though. But, even if it's the middle of July and you change your mind, there is nothing that is legally stopping you!
If you have already accepted an offer from School A, and you want to change to School B before April 15, then it's not really a big deal. Just accept School B and then tell School A you have changed your mind. It's not ideal, because School A people were probably planning on you arriving. However, it's before April 15, so they can still offer a spot to people on their waitlist.
After April 15, School B will probably require you to declare whether or not you have already accepted a previous offer. You would then have to get a "release" from School A and show that to School B before you can accept School B's offer. However, this still does not mean you were legally bound to School A -- this is just something School B requires so that there are no hard feelings between School A & B (i.e. School B is not trying to "poach" School A's students). In addition, School A people will likely be pretty upset at you. But they will almost always give you the letter of release (if you don't want to be there, they won't want you either). Also, there could be a person on School A's waitlist for whom School A is their dream school, but your delay causes them to not get an offer until after April 15, and they might have already accepted an offer somewhere else!
There are no real legal consequences to changing your mind after April 15. There will be some reputation damaged though, but it's not necessarily career-ending (although you might not be able to apply to the same department again in the future) if you handle it properly. In the end, everyone realises you have to make the decision that is best for you. You just have to decide if it's all worth it. As future professionals, we will have to make decisions in which someone loses.
Planetary Sciences PhD student
BSc (Physics & Astronomy) UBC 2010; MSc (Astronomy) at Queen's 2012
Feel free to message me about any of these schools, or about applying to US schools as a Canadian!