For a resale, the usual default position if no one says anything about it is for the buyer to pay the proportion of dues for the calendar year running from date of closing to end of year, even though seller may have already paid thru the year. However, you can find sellers who will want you to pay more if they still have a full load of annual points in the current use year, and you can also find sellers who want to do that even if they have already used all such points. Personally, even with a full load of points, i would not pay more than the proportional calendar share. Dues are based on a calendar year not use year, and if the seller has a full load of points, he can factor that into the asking price per point not the dues.
OP you should contact the broker and find out exactly what the broker thinks is going to happen with the dues. Closing in January creates an issue that requires you to seek clarification. In January, all dues for 2016 will be due and shown as due at time of closing. Someone will have to pay all of the 2016 dues as part of the closing because Disney will not allow you to set up monthly payments via withdrawals from your checking acocunt until after closing. Thus if seller is also insisting on your covering 2015 points, your facing having to pay two years worth of dues at closing. Frankly, if I were not closing until Jan and the seller insisted on getting 2015 dues, I would likely say no and if the seller insists, walk away. You have some bargaining power on that issue right now because the seller is facing the problem that he will have to pay 2016 dues if he does not do the sale with you and cannot immediatley find another buyer.
Bill
