19 CFR §113.40

1. (a)General provisions. In lieu of sureties on any bond required or authorized by any law, regulation, or instruction which the Secretary of the Treasury, the Secretary of Homeland Security, or the Commissioner of CBP are authorized to enforce, the Director, Revenue Division or, in the case of single transaction bonds, a port director, may accept United States money, United States bonds (except for savings bonds), United States certificates of indebtedness, Treasury notes, or Treasury bills in an amount equal to the face amount of the bond that would be required. The option to deposit cash or U.S. obligations in lieu of sureties is at the option of the importer, and a CBP Form 301 or other CBP-approved bond designating the appropriate activity for the cash deposits or U.S. obligations in lieu of surety must be filed. When cash or obligations in lieu of surety are accepted, it must be for a term of no more than one year. Additional cash deposits or obligations in lieu of surety may be required.
2. (b)Authority to sell United States obligations on default. At the time of deposit with the Director, Revenue Division, of any U.S. obligation (other than U.S. money), the obligor must deliver a duly executed power of attorney and agreement authorizing the Director, Revenue Division, in the case of any default in the performance of any of the conditions of the bond, to sell the obligation so deposited and to apply the proceeds of the sale, in whole or in part, to the satisfaction of any damages, demands, or deficiency arising by reason of default. The format of the power of attorney and agreement, when the obligor is a corporation, is set forth below and must be appropriately modified when the obligor is either an individual or a partnership:
3. (c)Application of United States money or obligations on default. If United States cash or obligations are deposited in lieu of surety on any bond, the appropriate CBP officer is authorized to apply the cash or money received from the deposited obligation to satisfy any damages, demand, or deficiency arising from a default under the bond.