Mich. Comp. Laws § 208.153

3. Affirmation of Existing Tax Liabilities Sec. 3. Except as specifically provided, this initiated law shall not affect the administration, allocation, or apportionment of the tax; payments to counties; nor any appropriation. The obligation of taxpayers and the state for taxes levied or collected on business activity on or before December 31, 2007 is affirmed.