(1) Where a railroad has income from sources both within and without this state, the amount of apportionable income from sources within this state shall be determined pursuant to Title 15, chapter 31, part 3, MCA, except as modified by regulation.

(2) For definitions, rules, and examples for determining apportionable and nonapportionable income, see ARM 42.26.206.

(3) Except as modified in this regulation, the apportionment factors shall be determined as follows:

(a) the property factor in accordance with ARM 42.26.231 through 42.26.237, inclusive;

(b) the payroll factor in accordance with ARM 42.26.241 through 42.26.244, inclusive; and

(c) the receipts factor in accordance with ARM 42.26.251 through 42.26.259, inclusive.