26 U.S.C.
United States Code, 2024 Edition
Title 26 - INTERNAL REVENUE CODE
Subtitle F - Procedure and Administration
CHAPTER 61 - INFORMATION AND RETURNS
Subchapter A - Returns and Records
PART IV - SIGNING AND VERIFYING OF RETURNS AND OTHER DOCUMENTS
Sec. 6064 - Signature presumed authentic
From the U.S. Government Publishing Office, www.gpo.gov

§6064. Signature presumed authentic

The fact that an individual's name is 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.

(Aug. 16, 1954, ch. 736, 68A Stat. 749.)