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Refund claims

Section 203 of the United States Code voids an assignment of a claim against the Government unless made after it has been allowed, the amount due has been ascertained, and a warrant for its payment has been issued.

If it were not for judicial development of certain exceptions, this section would prohibit a suit for refund by an acquiring corporation for taxes paid by a transferor corporation, even though the reorganization meets the requirements of section 381(a).