Mich. Comp. Laws § 206.105: Allocation and apportionment of business income taxable in another state.

Sec. 105.

For purposes of allocation and apportionment of income from business activity under this part, a taxpayer is taxable in another state if (a) in that state he is subject to a net income tax, a franchise tax measured by net income, a franchise tax for the privilege of doing business or a corporate stock tax, or (b) that state has jurisdiction to subject the taxpayer to a net income tax regardless of whether, in fact, the state does or does not.