The assessment generated by municipalities is what the assessor or appraiser felt the property was worth the year the assessment was done. It is used to distribute tax burden amongst residents within that property taxing district. The FMV listed on tax bills is generated by the department of revenue based on transfer tax returns from actual sales during the year. The state uses it to determine shared revenue. If a municipality does not reassess for a number of years, they would get to few or to many state dollars depending on whether prices are going up or down. Also, even though the department of revenue breaks sales into 7 or 8 categories, the actual multiplier used to generate FMV is often a blended number. Both the assessment and FMV do a reasonable job telling you whether one property is worth more or less than another, the margin of error is usually greater than a broker's opinion or appraiser. Condition of property causes the greatest error. You will often find properties in outstanding condition exceeding FMV and property in poor condition well below. Since many municipalities use mass appraisals, you find the occasional error in data entry. Garbage in, garbage out. There is nothing wrong with agents using statements of facts, when promoting their listings.