Indiana Code Title 6. Taxation § 6-3-2-1.9

(1) in the case of an individual, or, except as provided in subdivision (3) or (4), a corporation, federal taxable income as defined in Section 63 of the Internal Revenue Code;

(2) in the case of an estate or trust, federal taxable income as defined in Section 641(b) of the Internal Revenue Code;

(3) in the case of an insurance company subject to the tax imposed under Section 831 of the Internal Revenue Code, federal taxable income as defined in Section 832(b) of the Internal Revenue Code;  and

(4) in the case of a life insurance company subject to the tax imposed under Section 801(a) of the Internal Revenue Code, federal life insurance company taxable income as defined in Section 801(b) of the Internal Revenue Code.