i don't think you will after 1/31/13 because you wont be able to use them unless they were already banked. --- Eating broccoli is good for your health but wings, donuts, cookies, and brownies are good for a spartans health while playing with himself (On halo).
Wait. So banked means in the system on the website, right? Then applied means actually applied to the gamertag.
So we have until 3/31/13 to use all the double xp?
Edit: I found this.
The maximum amount of XP Matches for any Gamer ID/Gamer tag during the Promotion Period is 200 Matches. XP Matches must be transferred to a Gamer ID/Gamer tag no later than 3/31/13 or they will be forfeited. If no Gamer ID/Gamer tag has been entered during the Promotional Period, all XP Matches will be forfeited.
So I think I answered my question. --- Always O.G.