31 U.S.C. § 3727 : US Code - Section 3727: Assignments of claims

      (a) In this section, "assignment" means - 
        (1) a transfer or assignment of any part of a claim against the
      United States Government or of an interest in the claim; or
        (2) the authorization to receive payment for any part of the

      (b) An assignment may be made only after a claim is allowed, the
    amount of the claim is decided, and a warrant for payment of the
    claim has been issued. The assignment shall specify the warrant,
    must be made freely, and must be attested to by 2 witnesses. The
    person making the assignment shall acknowledge it before an
    official who may acknowledge a deed, and the official shall certify
    the assignment. The certificate shall state that the official
    completely explained the assignment when it was acknowledged. An
    assignment under this subsection is valid for any purpose.
      (c) Subsection (b) of this section does not apply to an
    assignment to a financing institution of money due or to become due
    under a contract providing for payments totaling at least $1,000
    when - 
        (1) the contract does not forbid an assignment;
        (2) unless the contract expressly provides otherwise, the
      assignment - 
          (A) is for the entire amount not already paid;
          (B) is made to only one party, except that it may be made to
        a party as agent or trustee for more than one party
        participating in the financing; and
          (C) may not be reassigned; and

        (3) the assignee files a written notice of the assignment and a
      copy of the assignment with the contracting official or the head
      of the agency, the surety on a bond on the contract, and any
      disbursing official for the contract.

      (d) During a war or national emergency proclaimed by the
    President or declared by law and ended by proclamation or law, a
    contract with the Department of Defense, the General Services
    Administration, the Department of Energy (when carrying out duties
    and powers formerly carried out by the Atomic Energy Commission),
    or other agency the President designates may provide, or may be
    changed without consideration to provide, that a future payment
    under the contract to an assignee is not subject to reduction or
    setoff. A payment subsequently due under the contract (even after
    the war or emergency is ended) shall be paid to the assignee
    without a reduction or setoff for liability of the assignor - 
        (1) to the Government independent of the contract; or
        (2) because of renegotiation, fine, penalty (except an amount
      that may be collected or withheld under, or because the assignor
      does not comply with, the contract), taxes, social security
      contributions, or withholding or failing to withhold taxes or
      social security contributions, arising from, or independent of,
      the contract.

      (e)(1) An assignee under this section does not have to make
    restitution of, refund, or repay the amount received because of the
    liability of the assignor to the Government that arises from or is
    independent of the contract.
      (2) The Government may not collect or reclaim money paid to a
    person receiving an amount under an assignment or allotment of pay
    or allowances authorized by law when liability may exist because of
    the death of the person making the assignment or allotment.