As long as you are using your
DVC points for a reservation and are not paying cash for a room, then:
If you use your DVC points to stay at an hotel in the Disney Collection, like the
Disneyland Hotel or the Polynesian Resort, I would expect that you would have to pay a hotel tax. Because those hotels are subject to the state's/county's hotel taxes. Whereas a timeshare is exempt from the hotel taxes.
Also if you are paying for
Disney Dining Plan you will be expected to pay for that in advance.