I like Indrik's idea.
In some ways it would be nice to tweak it so that when a knight pauses all the knights in the region would benefit as well. Perhaps it could be split among the estates and then taxed it's way up to the lord/duke/king. For lords/dukes/kings the option could either be that the funds are given to lieges or to estates under their authority. Meaning all regions in a duchy would benefit from their Duke, and all regions in the realm would benefit a very small amount from the king. What happens now if there is no duke at tax time? Does the crown get anything from the duchy?
It all depends on whether you want the gold going up or down. in either case you have to make an exception at the top or bottom.
