Use year month is key to banking deadlines and borrowing activities. There have been some amazing use year threads on this board.
Broadly speaking you want your use year to be the same month as your vacation time and if possible within the 100% banking deadline of any subsequent normal vacation times
For us our vacation windows are Dec and March in a normal year (the last one has not been normal) and as such we purchased December use year
In our case, we can use our December04 (for example) points against our December and March vacations and if we are not able to use them all then bank them forward to the December05 use year period (covers Dec 1, 2005 to November 30, 2006)
thanks
jaysue