You can change the auto tax to whatever loyalty level you choose. ECS, one of the programmers enlightened us on this in another thread.

For example if you want an auto tax to maintain loyalty of 200%, right click the mtw shortcut on your desktop, then properties and add the following switch:

-loyalty:200

If your MTW is installed to the default directory, your command line should look like this:

C:\Program Files\Total War\Medieval - Total War\Medieval_TW.exe -loyalty:200

You can change it to 150, 130 or whatever. Of course the game currently manages taxes on a loyalty basis and not on an income basis.

A feature that combines criteria you set would be VERY useful.