How We Determine Your Residential Assessed Property Value

I am writing this article because I have a lot of contact with citizens who want to know how in the world we arrived at their assessed value.

To start with, let me give you some general information, some timelines, and then the actual process we use in Spokane County to determine your residential assessed value.  First of all, the county assessor determines your assessed value and mails your assessment notice to the owner address the assessor has on file. The county treasurer determines your property taxes and mails your tax statement to the taxpayer address the treasurer has on file. The assessor and treasurer maintain distinct/separate address files even though both addresses you have on file may be identical.

When you receive your assessment notice which we mail approximately June 1 of each year, you will see some dollar values: a land value, an improvement value (any structure/building on the property), and a total assessed value. Your property tax bill is based on the total assessed value. Also, the total assessed value is the only value you can appeal to the Board of Equalization.  Washington State Law does not allow owners to appeal either the land value or improvement value separately, only the total assessed value.  Basically, appraisers in the assessor’s office have some latitude in allocating these two separate values to arrive at the total assessed value.  Periodically, our appraisers adjust the value of land relative to the total value of properties.  When developed properties sell, both the land and the buildings are sold as one; there is no distinction of value allocated between the land and the home. We often account for the increasing value of properties by allocating the increase to the buildings only.  However, some years our appraisers adjust land values to better reflect a more realistic allocation of value.  Remember, your total assessed value is what you’re taxed on.

In Spokane County, properties are revalued annually and inspected once every six years. An inspection is normally an exterior viewing of the property and involves updating any number of features, such as, additions, quality of construction, and overall condition of the property.

When all appraisal work is completed, home values are updated by computer assisted mass appraisal (CAMA) software that uses the industry standard in cost tables provided by a company named Marshall & Swift.  This software calculates your assessed value using a mass appraisal cost model. Local market factors based on criteria such as location, size, and architectural style are applied to the depreciated replacement cost to arrive at market value. Market factors are derived from real estate sales. Market value is considered to be within a value range and not an exact number. In short, assessed home values are recalculated statistically. Assessed values are not calculated based upon specific comparable sales. They are validated by the previous year’s real estate “sales” of all comparable properties.  Therefore, when a homeowner asks for the specific comparable sales used to establish their assessed value, they simply don’t exist; because that’s not the methodology used to calculate it.

These values are then used as part of a formula (assessed value x levy rate = tax bill) to calculate the following year’s property taxes.