42.26.309 APPORTIONMENT FACTORS
(1) For purposes of 15-31-322, MCA, the assignment of payroll and property is determined under the individual states' laws and regulations that set forth the apportionment formulas used to assign net income subject to taxes on or measured by net income. If a state does not impose a tax on or measured by net income, assignment is determined under this chapter.
(2) The apportionment provisions of Title 15, chapter 31, part 3, MCA, and related regulations regarding the inclusion, valuation, and attribution of apportionment factors by location shall apply to the computation of Montana tax liability under a water's-edge election. Only property, payroll, and receipts of corporations actually included in the water's-edge combined group shall be considered.