Election to include every member of commonly controlled group.

The designated agent as provided in sub. (7) may elect, without first obtaining written approval from the department, to include in its combined group every corporation in its commonly controlled group, regardless of whether such corporations are engaged in the same unitary business as the designated agent. Corporations included in the combined group by operation of this election are required to use combined reporting only to the extent described in sub. (2). The commonly controlled group shall calculate its Wisconsin income and apportionment factors as provided under subs. (3), (4), and (5), and all income of all members of the commonly controlled group, whether or not such income would otherwise be subject to apportionment or allocable to a particular state in the absence of an election under this subsection, shall be treated as apportionable income for purposes of the combined report.

The election under this subsection shall be executed by the designated agent on an original, timely filed combined report. Any corporation that becomes includable in the commonly controlled group subsequent to the year of election shall have waived any objection to its inclusion in the combined report.

The department may not disregard the tax effect of an election under this subsection, or disallow the election, with respect to any controlled group member or members for any year of the election period.