Bank Guarantee Accounting is an irrevocable commitment by a bank to pay a specified sum of money in the event that the party requesting the guarantee fails to perform the promise or discharge the liability to a third person in case of the requestor’s default. BONDING is generally used by service companies as a guarantee to their clients that they have the necessary ability and financial tracking to meet their obligations. Bonds are also used to guarantee payment of duty for U.S. Customs entry.