Administrative Rules of Montana
Department 42 - REVENUE
Chapter 42.15 - INCOME TAX
Subchapter 42.15.3 - Tax Returns
Rule 42.15.303 - RETURNS FOR THOSE UNABLE TO MAKE OWN RETURN

(1) Any taxpayer who for any reason is unable to make a return may have the return made by a designated agent. In the case of a minor, the return may be made by the minor or by a guardian or other person charged with the minor's care or property. In the case of a taxpayer who is mentally or physically incapable of making a return, the return for such person shall be made by the guardian or other person charged with the care of the taxpayer's person or property.

(2) A return must be filed for a decedent covering the period from the beginning of the taxable year to the date of death. If the deceased taxpayer was married, a joint return may be filed to include the income of the decedent for the period the decedent was alive and the income of the surviving spouse for the entire taxable year. The executor or administrator of the decedent is responsible for making the decedent's return.