In real estate law, a property assessment is an estimate of the value on a particular piece of property. It is usually conducted for the purpose of calculating property taxes or for determining resale values. A property assessor will determine the value of the home, or its “appraised value”. They will then multiply the value by the going tax rates in order to determine how much the property owner owes in taxes.   
The assessment is typically performed by an employee of the County Assessor. This is different from an appraisal, which is usually performed by a private professional in connection with the sale of a home rather than for tax purposes.
Property can be assessed using a variety of different calculations, which vary according to state laws and even by neighborhood zoning polices. Common methods for assessing property include:
  • Calculating the property value based on the income derived from the property
  • Using the resale market value of the property (this is the most common method)
  • Generating figures based on cost replacement, i.e., calculating the total monetary amount it would cost in materials and labor to rebuild the home

Why Would I Challenge an Assessment of My Property?

Although assessments are conducted by the government, it is possible for a property assessor to make errors when calculating the value of a home. If you feel that your property was wrongly assessed, you might want to consider challenging the assessment through an appeal or a lawsuit.  
The most common error is when the property is over-valued. This happens when the assessor’s calculations yield a figure that is more expensive than the home really is. An over-valuation can be a problem because it will result in overpayment on taxes. If the property is listed with a higher value than it actually is, then you will have to pay more taxes on the property. 
These overpayments on taxes can build up over the years. Especially for more expensive homes, wrongly assessed properties have led to lawsuits involving millions of dollars in overpaid taxes. The home owner would be entitled to retribution for the amount of taxes that they overpaid.
On the other hand, an under-valuation of the property can also be problematic. Under-valuation can lead to losses for the property owner on future sales of the home, or other problems with tax statements.

How do I Challenge a Property Assessment?

When your property is assessed, the assessing board will send you a “Notice of Assessment”. This document contains important information regarding your property appraisement. It should also include instructions on how to appeal the assessment before the local board. 
When you make an appeal you will need to present evidence that the appeal is erroneous. In order to prove this you should take the following steps:
  • Gather all records related to the valuation of your property, including prior assessments, recent tax statements, and a copy of the report that you feel contains errors
  • Obtain information on the assessment values of neighboring properties. These are usually available in public records. Compare them with the results of the assessment on your home. 
  • You will want to look for clues as to why the assessment was in error. For example, the assessor may have mistakenly listed an additional bedroom in your house, which resulted in higher figures. Or, the assessor could have used the wrong tax formula. Make note of any suspicious discrepancies in the statements
An appeal will likely be successful if it can be proven that the assessor made a serious error that affected the listing of your home’s value. Also, certain exemptions, such as veteran’s or POW exemptions could play a role in the mistakes.
Every state has different procedures for filing an appeal. Some states have a multi-layered approach to appeals and challenges which involve several steps. Be sure to follow deadlines and submit your appeal in a timely fashion.   

Can I File a Lawsuit over Assessment Disputes?

If your appeal is unsuccessful, your next available recourse may be to file a complaint with a higher governing board. If this still does not resolve the issue, you should consider hiring an attorney to assist you with litigation in a civil court of law. 
Lawsuits over property assessment disputes are common occurrences. You should keep the records and documents that you have compiled from the original appeal, as these will provide evidence for the case. Also, your lawsuit will have a better chance of success if the assessment involved some form of malice or personal motive on the part of the assessor. A property or tax attorney can help make sure that your legal claims are proper according to state and local laws.