15-31-403. Rate of tax imposed -- income from sources within state defined -- alternative tax. (1) Except as provided in 15-31-401, there is hereby imposed upon every corporation for each taxable year an income tax at the rate specified in 15-31-121 and 15-31-122 upon its net income derived from sources within this state for taxable years beginning after December 31, 1970, other than income for any period for which the corporation is subject to taxation under part 1 of this chapter, according to or measured by its net income.
(2) Income from sources within this state includes income from tangible or intangible property located in or having a situs in this state and income from any activities carried on in this state, regardless of whether carried on in intrastate, interstate, or foreign commerce, but does not include interest paid on loans held by out-of-state financial institutions recognized as such in the state of their domicile, secured by mortgages, trust indentures, or other security interests on real or personal property located within the state, if the loan is originated by a lender doing business in Montana and assigned out-of-state and there is no activity conducted by the out-of-state lender in Montana except periodic inspection of the security.
(3) Pursuant to Article III, section 2, of the Multistate Tax Compact, any corporation required to file a return under this part and whose only activity in Montana consists of making sales and which does not own or rent real estate or tangible personal property within Montana and whose annual gross volume of sales made in Montana does not exceed $100,000 may elect to pay a tax of 1/2 of 1% of gross sales made in Montana during the taxable year. Such tax shall be in lieu of the tax otherwise imposed under this section. The gross volume of sales made in Montana during the taxable year shall be determined according to Article IV, sections 16 and 17, of the Multistate Tax Compact.