Michigan's property tax is based on:

Market value is not the direct basis for Michigan property taxes under Proposal A — while the state equalized value (SEV) is calculated at 50% of market value, the taxable value (which is capped and often lower than SEV) is the actual basis for the tax calculation, making 'market value' an oversimplification that ignores Proposal A's cap mechanism.

Purchase price alone is not the basis for Michigan property taxes; while a sale triggers an uncapping of taxable value and resets it to the SEV (50% of market value) in the year following the sale, the purchase price itself is not directly used as the tax base, and subsequent years' taxable value is again subject to the inflation-or-5% cap.

Square footage has no role in Michigan's property tax calculation; the state uses a value-based system rooted in taxable value as defined by Proposal A, not a physical measurement system, making this answer factually baseless in the context of Michigan property taxation.