(a) Individual retirement account

(2) The trustee is a bank (as defined in subsection (n)) or such other person who demonstrates to the satisfaction of the Secretary that the manner in which such other person will administer the trust will be consistent with the requirements of this section.

(n) Bank

For purposes of subsection (a)(2), the term “bank” means—

(1) any bank (as defined in section 581),

(2) an insured credit union (within the meaning of paragraph (6) or (7) of section 101 of the Federal Credit Union Act), and

(3) a corporation which, under the laws of the State of its incorporation, is subject to supervision and examination by the Commissioner of Banking or other officer of such State in charge of the administration of the banking laws of such State.

26 U.S. Code § 581 – Definition of bank

For purposes of sections 582 and 584, the term “bank” means a bank or trust company incorporated and doing business under the laws of the United States (including laws related to the District of Columbia) or of any State, a substantial part of the business of which consists of receiving deposits and making loans and discounts, or of exercising fiduciary powers similar to those permitted to national banks under authority of the Comptroller of the Currency, and which is subject by law to supervision and examination by State, Territorial, or Federal authority having supervision of banking institutions. Such term also means a domestic building and loan association.