How do I lower income from provinces (taxes, trade, farming etc)

Hello, I'm planning to add a building that would represent that the province is in the royal demesne (a simple feudal system so to speak). My idea is that provinces without this building (to represent that the province is ruled by vassals) would generate very little income (almost none) and this building would then give a huge income bonus to the province. This way I'm planning to change the game so that the total number of provinces doesn't really matter financially, but rather the number of provinces under royal control (ie provinces with this building).

My question is how to make the income generated from the province very low. Especially tax income should be almost zero. Which files should I edit and so on?

Thank you.

extract the files in the packs
mod the "export_descr_buildings"(EDB) file so ports and markets dont give a trade income bonus, maybe negative number may work to get income even further down.
Than mod the "descr_settlement_mechanics" file so for instance governors give huge bonusses (bonus of nothing is still pretty little!!) and buildings in general very poor bonusses.
Make your building available via the EDB-file and give it some hefty trade income bonusses, once a governer takes place there it will even add a bonus that big bonus(small bonus on lots of cash is still a nice bit of extra).

Dont know how far down you can get income without like removing trade items in regions, but I guess you'd be able to go pretty far with the above.


G

Ok, thanks.
The bonuses in the EDB file are numbered in low numbers (1, 2, 3, 4, 5 etc), how much difference can I really make by lowering this numbers? I really want the settlements to earn as little money as possible and when my royal demesne building is built, they will generate normal income. And how can I make taxes lower?
I don't want to involve governors, since I want the building alone to "lock up" the income from a province. Is there a general income bonus that affects all kinds of income?

You have to edit descr_settlement_mechanics.xml

Right, I'll do that...