Carol did an excellent job explaining the banking/borrowing rules.
I just wnted to add one point. The 50% and 25% banking deadlines need a little more explaining, you can only bank 50% TOTAL, using the same 200 point example, you can bank 100 points by Oct 31. BUT, if you had already banked, say 50 points prior, you can only bank an additional 50 points (100 total). Like wise with the 25% date, if you have allready banked 50 points or more, you can not bank additional. This got me my first year back in '93. I assumed I could bank an additional 50% at the 9 month date, and had already banked some points prior to that. So I was FORCED to make another trip. You do get a once in a life time banking exemption, to bank what ever amount of point you have. BUT ONLY ONCE, use it wisely.