When the guild reaches rank 3, the option for tax & tithe opens up. Guild taxes are pretty self-explanatory: The guild leader can determine a percentage of your earnings that will go to the guild vault. The tax rate will show in the rewards tab next to the tax option.
What exactly is the tithe then? The tithe option is a voluntary contribution from each player towards the guild vault. While the tax is imposed equally for all guild members, the percentage of the tithe rate can be selected by everyone differently. If you want to donate to your guild bank, just click the tithe option inside the guild reward window and a small pop-up will open, here you enter the percenetage of you earnings you want to give.
Both options, tax & tithe, will add up. So if your guild has a basic tax of 5% and you choose a 7% tithe rate, you'll donate 12% of your income to the guild. I think i read somewhere it's rounded down where it applies. I'm not 100% sure, but i also recall the deducted money is only taken away from looting corpses and not doing quests, vendor sales or income from the auction house.
