Bug or feature, I don't know.

[Saxon]

Are you sure about the gold income? I just took a sweet province and my income jumped, while the opponent's dived. However, that is just based on graphs, I did not check actual income.

If you are right, most of the time I would drop the tax to zero, hurt the enemy income and quell unrest. Even if I though I would lose the seige, I would still zero the taxes, unless I thought it was worth getting the unrest up high.