For religions, wouldn't it be an option to increase the "dontaions" from the peasents a little bit to counter the taxes? If you have an low amount of gold in a temple you could gain some gold, as donations would be higher then the tax. But if you store huge amounts of gold in a temple the tax would kick in and you would loose more gold then you gain.
This way the burden of keeping all temples supplied will become smaller, as well as removing the option to "hoard" a lot of gold in temples.
Of course this would not solve the problem for guilds
