(a) If it shall appear to the satisfaction of the Center director holding the bond referred to in § 10.80, that the entire quantity of salt covered by the bond has been duly accounted for, either by having been used in curing fish or by the payment of duty, the Center director may cancel the charges against the bond. The Center director may require additional evidence in corroboration of the proof of use produced.

(b) On application of the person making the withdrawal, the period of the bond may be extended 1 year so as to allow the salt to be used during the time of extension in curing fish with the same privileges as if used during the original period.