Calendar year memberships with early signup?

I’m new to S2Member. I’m creating a site for a organization that has calendar year memberships and allows anyone who joins after October 1 each year to extend their membership through the next calendar year. (I.e., if I joined today – 11/8/13 – my membership would end on 12/31/14.) Or, another way to look at it, if I joined anytime between 10/1/13 through 9/30/14 my membership would end 12/31/14. Has anyone done something like this with S2Member?