Not true Viking, when I became Gaul's protectorate as Spain, not only did I not have to pay anything apart from my treasury that turn (which already run down almost to zero by then, since I empty my treasury every turn), they even paid me heap big heap tribute (2000 a turn for 6 turns, if i recall) and that gave me a HUGE early-game boost since I was already making net 2000+ a turn at that time holding Corduba, Tingi and Numantia. So in turn 12 I was actually making about 4-5k a turn, and up to 6-7 by selling map info. And this with only 7 provinces. I swear to you I felt like Egypt :-P