The Tax Assessorís office plays an important role in determining how much a property owner pays the government for Ad Valorem (Latin: by value) taxes. The tax assessorís office generally has a coverage area called a tax district. This may be a local municipality, a county or a regional area as determined by the governing body for the area or the Stateís Department of Taxation. In many areas, the assessor is local and the assessorís office covers just one municipality (though the assessor may be part-time and work separately for other municipalities).
Periodically, a tax district will do what is called a re-valuation. Tax assessors will often retain a mass appraisal firm that goes out and inspects every property in the taxing districtís coverage area. So the Tax Assessor may not be the actual person that establishes the taxable value for your property. It will often be outsourced. The mass appraisers will typically visit each property, collect data about it and establish an assessment for it. Generally the assessment will be broken into a land assessment and an improvements (structures such as houses, buildings, etc.) assessment. In some jurisdictions, machinery and equipment are also taxed.
The first year the assessments are released, they should be at 100% of value but as time goes on, that percentage can fall or rise depending on whether properties go up or down respectively. Each subsequent year, a percentage will typically be established called an equalization ratio. The ratio is established by comparing assessed values of properties that sold to their actual sale price. Assessors usually have the right to deem some sales as unusable because the buyer and seller were not arms length (uninvolved) parties or the sale is the result of a legal proceeding (bankruptcy, divorce, estate, etc.). The remaining arms length transactions are used to establish the ratio. In most tax districts, the assessments are not adjusted annually and the ratio is a number that is only used for determining fair market value. This might be in contemplation of filing a tax appeal or not. It might also be in consideration of selling the property.
Other taxing districts use a more straight-forward method of applying the ratio each year to the assessed value and adjusting the assessment to 100% each year. This is called re-assessment (as opposed to a re-valuation where each property is visited). With a re-assessment, a computer will typically apply the ratio and generate the new assessments.