This is some combination of complaint and feature request.
As it currently stands, banker can *really* surprise the realm with new taxes, collecting a few thousand dollars before running off somewhere or otherwise transferring the gold to the family.
We just had a banker hike up all taxes (wealth/property) to 25% and set the wealth/property taxable amounts to 1 and 2 gold respectively.
1. It should not be possible to tax gold in excess of 25-50 coins. Minimum of 1 gold makes little sense. A noble that only has 25 gold coins would likely kill any tax collector.
2. Changes to the tax code should be announced to the realm - particularly the major ones. That's the kind of thing that would start lots of rumors among the nobles.
3. It shouldn't even be possible to make such a quick change! In the region taxes, as a Lord, I can only raise taxes by 3 percent every turn. The banker should be similarly limited to 1-3% every day and maybe even in how much the taxable limits can be changed too (ours was several thousand before he changed it to 1.).