b) change the tax type - I could store the amount of gold put into the treasury between tax days, and tax only that, i.e. turn it into an income tax. This would also reduce the lord = massive balance problem a little, but it would reduce income through guildhouses dramatically.
This option sounds much better to me. You would, for example, deposit 100 gold in a temple located in a 10% taxed region, and it would reply something like this to you: "You have deposited 95 gold in the temple. 5 gold goes to the local lord's tax office" (if the 50% taxes' reduction for temples is still on, of course).
