Everyone can deposit money into the guild bank (you need to have the money on you, you can't transfer directly from your bank account) but only the leader and vice leaders can withdraw it.
Deposit into guild bank
Players cannot transfer from their bank account to a guild bank account. Thus, in order to make a guild deposit, the player must carry the gold with him. Players can deposit into their guild bank with the keyword chain guild deposit > (amount) or by the abbreviated guild deposit (amount).
Withdraw from guild bank
Guild leaders and vice leaders can withdraw money from the guild bank. The money will be transferred into the player's bank account. The keyword chain is similar to that of depositing: guild withdraw > (amount), or guild withdraw (amount).
Transfer from one guild to another
Guild leaders and vice leaders can also transfer money from one guild bank to another. They can do this with the keyword chain guild transfer > (amount) > (recipient guild), or guild transfer (amount) > (recipient guild), or guild transfer (amount) to (recipient guild).
Transfer from Guild to player
Guild Leaders and Vice leaders can also transfer money from the guild bank directly to another player. They can do this with the keyword chain Guild player transfer > (amount) > (recipient player) or Guild player transfer (amount) to (recipient player)
http://tibia.wikia.com/wiki/Guild_Bank