From what I have heard, if you add the MaxPass as part of the renewal (something you can't do online so you have to renew in person or by phone to do this), then the MaxPass becomes active the first day of your new year and works through the new expiration date. So say you go to the ticket booth this weekend and renew, adding MaxPass to the renewal. The MaxPass will not work for you this weekend but will become active whichever date in November is the first day of your new pass year. If you were to just renew your AP online and then add MaxPass separately at the park before your renewal date, I suspect that the MaxPass would only be through the rest of your current year. Since you can only add Maxpass at the ticket booth or on the phone I guess it doesn't hurt to ask, but if I was paying $75 for it, I would want to be very clear on when it's set to begin and expire. Hmm...that sounded very convoluted. Let me know if I'm too unclear about what I'm saying. I would love if I could renew and add MaxPass and have it work immediately, even before my official expiration date, but from the stories I have heard and Disney's fine print, I don't think it works that way. I read one account early on where it did work that way for someone but have not seen any such reports since.