The Michigan Court of Appeals held that the mandatory apportionment provision of the Michigan Single Business Tax Act did not impliedly repeal Michigan’s enactment of the Multistate Tax Compact’s alternative apportionment election provision. In addition, the court held that the Single Business Tax (SBT) was an income tax under the Compact’s definition, and the state’s retroactive repeal of the Compact by PA 282 (2014) did not extend to the SBT for tax years prior to 2008. Thus, taxpayers are allowed to make the Compact’s apportionment election for periods prior to the enactment of the Michigan Business Tax. AK Steel Holding Corp. v. Dep’t of Treasury, Nos. 327175, 2016 WL 744071 (Mich. Ct. App. Feb. 25, 2016).