(a) If the affected farmer or manufacturer is indebted to any agency of the United States and such indebtedness is listed on the county debt record, indemnity payments due the affected farmer or manufacturer under the regulations in this part shall be applied, as provided in the Secretary's setoff regulations, part 13 of this title, to such indebtedness.(b) Compliance with the provisions of this section shall not deprive the affected farmer or manufacturer of any right he would otherwise have to contest the justness of the indebtedness involved in the setoff action, either by administrative appeal or by legal action.