(a) Corporations which by reason of their purposes or activities are exempt from federal income tax: Provided, That this exemption shall not apply to the unrelated business income, as defined in the Internal Revenue Code, of any such corporation if such income is subject to federal income tax.
(b) Insurance companies which pay this state a tax upon premiums and insurance companies that pay the surcharge imposed by subdivision (1) or (3), subsection (f), section three, article two-c, chapter twenty-three of this code.
(c) Production credit associations organized under the provisions of the federal Farm Credit Act of 1933: Provided, That the exemption shall not apply to corporations or associations organized under the provisions of article four, chapter nineteen of this code.
(d) Corporations electing to be taxed under subchapter S of the Internal Revenue Code of one thousand nine hundred eighty-six, as amended: Provided, That said corporations shall file the information return required by section thirteen-b of this article.
(e) Trusts established pursuant to section one hundred eighty-six, chapter seven, title twenty-nine of the code of the laws of the United States (enacted as section three hundred two (c) of the Labor Management Relations Act, one thousand nine hundred forty-seven), as amended, prior to the first day of January, one thousand nine hundred sixty-seven.