Property tax rates (also known as ad valorem taxes) in most states, including Oklahoma, are set in mills. A mill is $1 in tax for every $1,000 in taxable value. For convenience in Oklahoma, a tax rate (the sum of all mills levied) is expressed as dollars per thousand dollars of assessed value. A tax rate of 80 mills, for example, would be $80 in property tax for every $1,000 in taxable value.

Each government sets its mill rate based on budgetary needs, subject to constitutional limits on mill rates and voter approval in most cases. Counties and school districts levy the highest mills and can assess separate mills for a range of different funds. Other entities levying mills are cities, vo-tech centers, community junior colleges, fire protection districts, emergency medical service districts, sewer improvement districts, and rural road improvement districts. Most recently, the Legislature in 2021 passed legislation allowing municipalities, with a 60 percent vote of the people, to create a public safety protection district funded through a property tax assessment of as much as 5 mills. County Treasurers review and approve the mill rates and prepare property tax bills that add up all the mill rates for each government to determine an overall mill rate for each property.

Millage rates in Oklahoma are commonly in the range of 90 to 110. These rates would result in a yearly tax bill of $900 to $1,100 on a $100,000 owner-occupied home.