26 CFR § 1.6062-1 - Signing of returns, statements, and other documents made by corporations.
(a) Returns -
(1) In general. Returns required to be made by corporations under the provisions of subtitle A or F of the Code, or the regulations thereunder, with respect to any tax imposed by subtitle A of the Code, shall be signed for the corporation by the president, vice-president, treasurer, assistant treasurer, chief accounting officer, or any other officer duly authorized to sign such returns. It is not necessary that the corporate seal be affixed to the return. Spaces provided on return forms for affixing the corporate seal are for the convenience of corporations required by charter, or by law of the jurisdiction in which they are incorporated, to affix their corporate seals in the execution of instruments.
(2) By fiduciaries. A return with respect to income required to be made for a corporation by a fiduciary, pursuant to the provisions of section 6012(b)(3), shall be signed by such fiduciary. See paragraph (b)(4) of § 1.6012-3.
(b) Statements and other documents. Statements and other documents required to be made by or for corporations under the provisions of subtitle A or F of the Code, or the regulations thereunder, with respect to any tax imposed by subtitle A, shall be signed in accordance with the regulations contained in this chapter, or the forms and instructions, issued with respect to such statements or other documents.
(c) Evidence of authority to sign. An individual's signature on a return, statement, or other document made by or for a corporation shall be prima facie evidence that such individual is authorized to sign such return, statement, or other document.