Millage for vehicles change, January of each year. For example, if your tag renews within the calendar year of 2017, then your tax rate is based upon 2016 millage. If the tag renews in January 2018, then the taxes are based upon the 2017 millage rate. Vehicle taxes are paid in advance.
Taxes for real estate, airplanes, boats and motors and Business Personal Property (PT-100) are based upon ownership as of December 31st of the prior year and you are taxed on the new millage rate approved in September of the respective year. These taxes are paid in arrears.