Disclosure.

For each taxable year in which a taxpayer has participated in a reportable transaction, the taxpayer shall file with the department a copy of any form required by the internal revenue service for disclosing the reportable transaction for federal income tax purposes no later than 60 days after the date for which the taxpayer is required to file the form for federal income tax purposes, except that, if the taxpayer has filed a form with the internal revenue service on or before October 27, 2007, the taxpayer shall file a copy of the form with the department no later than May 31, 2008. The department may require that forms filed with the department under this subsection be filed separately from this state’s income or franchise tax return. This subsection applies to any reportable transaction entered into on or after January 1, 2001, or any reportable transaction entered into prior to January 1, 2001, that reduced the taxpayer’s tax liability for taxable years beginning on or after January 1, 2001, for any taxable year for which the transaction remains undisclosed and for which the statute of limitations on assessment, including any extension provided under sub. (6), has not expired as of the date that is 60 days after October 27, 2007.