Points can only be banked forward once. Also, once points are banked or borrowed they cannot be returned to their original year.
As you probably know, you get your points based on your Use Year. If your year is April, you will get points on April 1, 2003 that are good through March 2004. If you bank these points, they then become available to use for trips taken between April 1, 2004 and the end of March 2005. It is possible to bank points, have current points and borrow points allowing you to use 3 years' worth of points in one year.
The banking decision has to be made early in the year in order to bank all the points. As the year winds down you are only allowed to bank up to 50% and then up to 25% of your points. During the final 60 days of the year, you can no longer bank points.
