Mont. Code Ann. § 15-31-101 — Organizations Subject To Tax -- Incorporation Of Terms That Mean Corporate Income Tax

15-31-101 . Organizations subject to tax -- incorporation of terms that mean corporate income tax. (1) The term "corporation" includes an association, joint-stock company, common-law trust or business trust that does business in an organized capacity, all other corporations whether created, organized, or existing under and pursuant to the laws, agreements, or declarations of trust of any state, country, or the United States, and any limited liability company, limited liability partnership, partnership, or other entity that is treated as an association for federal income tax purposes and that is not a disregarded entity.
(2) The terms "engaged in business" and "doing business" both mean actively engaging in any transaction for the purpose of financial or pecuniary gain or profit.
(3) Except as provided in 15-31-103 or 33-2-705 (4) or as may be otherwise specifically provided, a corporation engaged in business in the state of Montana shall annually pay to the state treasurer a corporate income tax for the privilege of carrying on business in this state the percentage or percentages of its total net income for the preceding tax year at the rate set forth in this chapter. If a corporation has income from business activity that is taxable both within and outside of this state, the corporate income tax must be measured by the net income derived from or attributable to Montana sources as determined under part 3. Except as provided in 15-31-502 and subject to the due date provision in 15-31-111 (2)(b), the tax is due and payable on the 15th day of the 5th month following the close of the tax year of the corporation. However, the tax becomes a lien as provided in this chapter on the last day of the tax year in which the income was earned and is for the privilege of carrying on business in this state for the tax year in which the income was earned.
(4) A bank organized under the laws of the state of Montana, of any other state, or of the United States and a savings and loan association organized under the laws of this state or of the United States is subject to the Montana corporate income tax provided for under this chapter. For tax years beginning on and after January 1, 1972, this subsection is effective in accordance with Public Law 91-156, section 2 (12 U.S.C. 548).
(5) Unless the context requires otherwise, when the words "corporation income tax", "corporation license tax", "corporate license tax", "license tax", "license fee", or similar words appear in the Montana Code Annotated referring to the tax imposed under this chapter, the terms mean "corporate income tax".