12. What is combined apportionment at the entity level?

If a taxpayer elects to file using combined apportionment it means companies operating as a unitary business are treated as if they are one company for apportionment purposes.  The sales factor is determined as a ratio of the combined Michigan sales and combined total sales, after the elimination of intercompany sales, of all entities that are unitary.  The sales factor ratio is applied to the combined income (loss), included in adjusted gross income, of all the unitary companies.