31 U.S.C. § 3713: Priority of Government claims

(a)(1) A claim of the United States Government shall be paid first when—(A) a person indebted to the Government is insolvent and—(i) the debtor without enough property to pay all debts makes a voluntary assignment of property; (ii) property of the debtor, if absent, is attached; or (iii) an act of bankruptcy is committed; or (B) the estate of a deceased debtor, in the custody of the executor or administrator, is not enough to pay all debts of the debtor. (2) This subsection does not apply to a case under title 11. (b) A representative of a person or an estate (except a trustee acting under title 11) paying any part of a debt of the person or estate before paying a claim of the Government is liable to the extent of the payment for unpaid claims of the Government.