How Property Tax is Determined

Determining Property Taxes

Wyoming Statutes require all property to be valued at fair market value except for agricultural land which is valued by its productive capability. The fair market or productive value is given on the Assessment Schedule, also called a Notice of Assessment.


To determine the final tax amount, there are a few terms which must be understood:

  • Market Value: The amount that a property could reasonably be expected to sell for, when the knowledgeable buyer and seller act prudently and are not affected by undue stimulus.
  • Assessment Rate: The statutory percentage of fair market value on which taxes are based. The Assessment Rate is 9.5% for agricultural, commercial, and residential property, 11.5% for industrial, and 100% for mineral production.
  • Mill: Literally one thousandth. Mill means $1 of taxes for every $1, 000 of Assessed Value. It is the Tax Rate or Mill Levy. The average Mill Levy in Sublette County is 64 mills or about $6.08 per $1,000 of market value on residential property.


The formula for determining actual tax dollars is as follows:

  • Fair Market Value times Assessment Rate equals Assessed Value
  • Assessed Value times Mill Levy (Tax Rate) equals Tax Dollars

The following is an example of how the tax amount for residential property is determined:

Tax CalculationAmount
Fair Market Value of property$200,000

Assessment Rate (9.5%)times 0.095

Assessed Value of property$19,000

Mill Levy / Tax Rate (64 mills)times 0.064

Amount of Taxes$1,216

Effective Tax Rate

The Effective Tax Rate equals the amount of taxes divided by the property value. This is the rate used to compare the tax burden from one area to the next.

In our example, it is $1,216 divided by $200,000 equals 0.0068 or 0.608%.

At the bottom of the Assessment Schedule or Notice of Assessment sent in April of every year, an estimated tax is given as well as the previous year's tax amount. The estimate is based on the previous year's Mill Levy for your tax district. The Treasurer's Office sends your actual tax bill in September after the County Commissioners, school boards, towns, and special districts have held their budget hearings and the final Mill Levies have been confirmed by the County Commissioners.

If you have any questions regarding your property's valuation, please contact the Assessor's Office at (307) 367-4374.