MI SB1170

Establishes a new "flow-through entity tax" on S corporations and partnerships beginning January 1, 2018, imposed at the same rate as the corporate income tax on positive business income allocated to the state.

Allows flow-through entities to make an irrevocable election to file a return and pay the tax directly rather than passing tax liability to individual members, with the election continuing for at least 3 tax years.

Provides a credit to individual members, estates, and trusts for their allocated share of tax paid by electing flow-through entities, with excess credits refundable.

Requires quarterly estimated tax payments for taxpayers expecting annual liability exceeding $800, with annual returns due within 3 months after the tax year ends.

Distributes tax revenue with 1.012% of gross collections deposited in the state school aid fund and remaining balance to the general fund; appropriates $5 million to the Department of Treasury for implementation.