Banking and Borrowing 101:
By way of example, assume you have a February use year meaning points this year were issued Feb 1 and expire Jan 31 of 2003:
1. You have until the end of the sixth month of your use year to bank all your current points into the next use year--thus on or before July 31 in our example, you can bank all your current points into 2003 and they will then be usable for a trip that occurs between Feb 1, 2003 and Jan 31, 2004. Those points once banked stay banked. You can't bring them back to this use year for a trip in 2002. Moreover they must be used in that 2003 use year as they cannot be banked again into 2004. (Of course the new points you get in Feb 2003 can then be banked into 2004.)
2. You also have until the end of your ninth month of your use year, October 30 in our example, to bank up to 50% of your total current use year points, and until the end of the tenth month (Nov 30) to bank up to 25%. But understand those are cumulative totals. If you bank 50% or more of your total annual points in your sixth month, you won't be able to bank any more in the 9th or 10th month; likewise, if you have banked 25% or more before the end of your 9th month you won't be able to bank anymore in that 10th month. It is very important to keep track of your banking dates if you plan to bank and understand that if the last banking date falls on a weekend you need to bank by the Friday of that week, or if it falls on a holiday by the last business day before that holiday.
3. Borrowing is done only when you call to reserve a trip (there is no reason to do so otherwise). It goes by the year of your trip. For example, suppose you call now to reserve June 2003 (with the 11 month home resort ressie window). With a Feb use year, you can use for that trip any points issued Feb 1, 2003 (which will be your "current" use year points for that particular trip), any points you have banked from the 2002 use year to the 2003 use year, and any points you borrow from the 2004 use year that begins Feb 1, 2004. You can borrow up to 100% of the points from a use year for a trip that will occur in the previous use year. Thus, for that June 2003 trip you could borrow all of your 2004 points. As with banked points, points once borrowed stay borrowed, so if you cancel your trip you will have borrowed points that cannot be sent back to the use year they came from. As a result if you borrowed those 2004 points for that June 2003 trip and canceled, those borrowed points will have to be used for a trip that is completed by Jan 31, 2004.