1. (1) The due date for filing an individual income tax return and payment of the tax due is the 15th day of the fourth month following close of the tax year.

2. (2) A return may be filed by personal delivery, mail, and electronically.

   1. (a) If a return is mailed as provided in this rule, on or before the due date, and received by the department, the return is considered filed on the date mailed. A taxpayer is responsible for establishing the date a return is mailed.
   2. (b) The rules for filing a return electronically are located in ARM Title 42, chapter 5, subchapter 2.

3. (3) Every taxpayer must compute their tax liability and pay the balance of any tax due in full on or before the prescribed due date, as stated in 15-30-2602, MCA. If the balance due is less than $1, payment is not required. If full payment of the balance due is not made on or before the prescribed due date, interest and late payment penalty accrue from the prescribed due date of the return until paid, as provided in 15-1-216, MCA.

   1. (a) If tax is paid by check or money order, the check or money order should be made payable to the "Montana Department of Revenue."
   2. (b) The rules for paying a tax electronically are located in ARM Title 42, chapter 5, subchapter 2.
   3. (c) The rules for paying a tax by credit card are located in ARM Title 42, chapter 5, subchapter 2.

Authorizing statute(s): 15-30-2620, MCA

Implementing statute(s): 15-30-2602, 15-30-2604, MCA

History: NEW, Eff. 12/31/72; AMD, 1982 MAR p. 14, Eff. 1/15/82; AMD and TRANS, from ARM 42.16.101, 2004 MAR p. 3153, Eff. 12/17/04; AMD, 2008 MAR p. 178, Eff. 2/1/08; AMD, 2010 MAR p. 1088, Eff. 4/30/10; AMD, 2025 MAR, 42-1088, Eff. 1/25/25.