Mich. Comp. Laws § 141.614: Excise tax on incomes; taxable net profits of a corporation, definition.

Sec. 14.

The tax shall apply on the taxable net profits of a corporation doing business in the city, being levied on such part of the taxable net profits as is earned by the corporation as a result of work done, services rendered and other business activities conducted in the city, as determined in accordance with this ordinance. "Taxable net profits of a corporation" means federal taxable income as defined in section 63 of the federal internal revenue code but taking into consideration all exclusions and adjustments provided in this ordinance. No deduction shall be allowed for:

Net operating losses and net capital losses sustained prior to the effective date of the tax.

The city income tax imposed by this ordinance.

A corporation may deduct income, war profits and excess profits taxes, imposed by a foreign country or possession of the United States, allocable to income included in taxable net income, any part of which would be allowable as a deduction in determining federal taxable income under the applicable provisions of the federal internal revenue code.