Why are property tax estimates so variable?

[Lewis Kerwin]

I'm in contact to buy a property in Redford Michigan. I noticed today that the seller's listing shows previous year tax of $907 but an estimate of $3200(!). Have been trying to use calculators online and am pretty confused. For instance this calculator on Michigan Dept of Revenue Property Tax estimator (https://treas-secure.state.mi....) seems to say the my home (market price 114K) would cost $4,676 in property taxes (assuming an "SEV" of 50% of market price). It states a millage rate of 82.03 Can this be right?!?