Income tax; unitary group; use of special apportionment formula; effect

Any member of a unitary group that is required or permitted to use an apportionment formula other than one prescribed by section 77-2734.05 shall be included in a return only with other corporations using the same apportionment formula. The income and the factors of such corporation shall not be used in computing the taxable income of the rest of the unitary group that does not use such special formula. A corporation using a formula required by a regulation issued pursuant to subsection (3) of section 77-2734.15 is using a formula prescribed by section 77-2734.05 .