Indiana Code Title 6. Taxation § 6-3-4-2

Sec. 2. (a) If an individual is deceased, the return of such individual shall be made by the individual's executor, administrator, or other person charged with the property of such decedent.

(b) If an individual is unable to make a return, the return of such individual shall be made by a duly authorized agent, the individual's committee, guardian, fiduciary, or other person charged with the care of the person or property of such individual.

(c) Returns of an estate or a trust shall be made by the fiduciary thereof.

(d) Where a joint return is made by husband and wife pursuant to the Internal Revenue Code, a joint return shall be made pursuant to this article.  Where a joint return is filed by a husband and wife hereunder, one spouse shall have no liability for the tax imposed by this article upon the income of the other spouse.

(e) Where separate returns are made by husband and wife pursuant to the Internal Revenue Code, separate returns shall be made pursuant to this article.