Currently, the deadline for taxpayers in counties with less than 150,000 inhabitants is the later of August 10 or 30 days after the publication of the assessment lists. In counties between 150,000 and 1 million inhabitants, the deadline is the later of September 10 or 30 days after the publication of the lists. In other words, the board of review should adjust the complaining taxpayer's assessment to the median level of assessment. The best case of over-assessment a taxpayer can make is through providing evidence of the fair cash value of property and then asking to be assessed at the median level of assessment. The key is to provide the board of review with evidence of the fair cash value of the property.
Several methods can be helpful.
Recent sale prices of similar property in the vicinity can also be good evidence. Selling prices tend to overstate the fair cash value if special financing is involved. Another method of indicating fair cash value is through appraisal. This may be feasible for only substantial assessment challenges, however, as the cost of the appraisal may outweigh the value of any tax relief. The law does authorize boards of review in counties of 100,000 or more population to hire independent appraisers if they desire.