Mont. Code Ann. § 15-31-322 — Water's-Edge Election

15-31-322 . Water's-edge election. Notwithstanding any other provisions of law, a taxpayer subject to the taxes imposed under this chapter may apportion its income under this section. A return under a water's-edge election must include the income and apportionment factors of the following affiliated corporations only:
(1) a corporation incorporated in the United States in a unitary relationship with the taxpayer and eligible to be included in a federal consolidated return as described in 26 U.S.C. 1501 through 1505 that has more than 20% of its payroll and property assignable to locations inside the United States. For purposes of determining eligibility for inclusion in a federal consolidated return under this subsection (1), the 80% stock ownership requirements of 26 U.S.C. 1504 must be reduced to ownership of over 50% of the voting stock directly or indirectly owned or controlled by an includable corporation.
(2) domestic international sales corporations, as described in 26 U.S.C. 991 through 994, and foreign sales corporations, as described in 26 U.S.C. 921 through 927;
(3) export trade corporations, as described in 26 U.S.C. 970 and 971;
(4) foreign corporations deriving gain or loss from disposition of a United States real property interest to the extent recognized under 26 U.S.C. 897; or
(5) a corporation incorporated outside the United States if over 50% of its voting stock is owned directly or indirectly by the taxpayer and if more than 20% of the average of its payroll and property is assignable to a location inside the United States.