In this paragraph, “pre-2009 net business loss carry-forward” means a corporation’s total net Wisconsin business loss carry-forward computed under s. 71.26 (4) or 71.45 (4) as of the beginning of its first taxable year that begins after December 31, 2008, but not used by the corporation in any taxable year beginning before January 1, 2012.

Starting with the first taxable year beginning after December 31, 2011, and for each of the 19 subsequent taxable years, and subject to the limitations provided under s. 71.26 (3) (n), for each taxable year that a corporation that is a member of a combined group has pre-2009 net business loss carry-forward, the corporation may, after using the pre-2009 net business loss carry-forward to offset its own income for the taxable year, and after using shareable losses to offset its own income for the taxable year, as provided under par. (b) 1., use up to 5 percent of the pre-2009 net business loss carry-forward, until used or expired, to offset the Wisconsin income of all other members of the combined group on a proportionate basis, to the extent such income is attributable to the unitary business. If the full 5 percent of such pre-2009 net business loss carry-forward cannot be fully used to offset the Wisconsin income of all other members of the combined group, the remainder may be added to the portion that may offset the Wisconsin income of all other members of the combined group in a subsequent year, until it is completely used or expired, except that unused pre-2009 net business loss carry-forwards may not be used in any taxable year that begins after December 31, 2031.

Unless otherwise provided by the department by rule, if the corporation may no longer be included in the combined group, as determined under this section, the corporation’s pre-2009 net business loss carry-forward shall be available only to that corporation.

The department shall promulgate rules to administer this paragraph.