Yes.
If you have 100 points in your contract (let's assume a June Use Year) and banked 100 points from your 2011 Use Year - you then used 107 points for a trip in December, 2012- you now have 93 points available for use before May 31, 2013. MS will normally use banked points first for any reservations (it is up to the member to make sure that is done) so you used the 100 points banked from 2011 and you now have 93 points from the current (2012) Use Year. You have until January 31, 2013 (the end of the 8th month of the Use Year) to bank those 93 points or you will lose them if not used for another reservation by May 31, 2013.
On June 1, 2013 you will have another 100 points available for use before May 31, 2014 or bank by January 31, 2013.