26 C.F.R. § 301.6064-1 Signature presumed authentic.
Title 26 - Internal Revenue
An individual's name signed to a return, statement, or other document shall be prima facie evidence for all purposes that the return, statement, or other document was actually signed by him.
Title 26: Internal Revenue
PART 301—PROCEDURE AND ADMINISTRATION
Information and Returns
records, statements, and special returns
§ 301.6064-1 Signature presumed authentic.