What Are the Most Common Mistakes in Property Tax Appeals?

 Posted on June 19, 2025 in Real Estate

Opening a property tax bill can be frustrating for many homeowners and property owners, especially when it feels higher than it should be. Appealing your property tax assessment can be a smart way to lower your costs, but the process is not always straightforward. Simple mistakes can make it much harder to get the relief you need. Working with a Cook County real estate attorney who understands the ins and outs of Illinois property tax law can make the process less stressful and give you a better chance of success.

Why Do People Misunderstand Their Property Assessment?

One of the first mistakes in a property tax appeal is misunderstanding how the property was assessed. Many people confuse market value with assessed value or do not realize that local equalization factors can affect their tax bill.

In Illinois, properties are assessed at 33 ⅓ percent of their fair market value. The Illinois Department of Revenue applies equalization factors to ensure consistency across different areas.

When Is the Deadline to File a Property Tax Appeal?

Missing the appeal deadline is one of the most common and costly errors. Each county in Illinois has a specific deadline after the publication of assessment changes, which is often within 30 days. Property owners who delay or overlook this window may lose their right to appeal for the year, so it is essential to stay informed about local deadlines and township notices.

What Happens When You Do Not Provide Evidence?

Another frequent error is filing an appeal without supporting documentation. Claiming your assessment is too high is insufficient – you must show why your property is overvalued or inaccurately classified. Proper forms of evidence include:

• Recent sales of comparable nearby properties

• Independent appraisals or valuation reports

• Photos showing physical damage or deterioration

• Floor plans, surveys, or blueprints that show incorrect property data

Can You Rely on Online Valuation Tools?

It may be tempting to use online real estate sites for valuation estimates, but these tools are not accepted as valid proof in a formal appeal. These algorithms often utilize incomplete or outdated data and lack the reliability that is needed for tax purposes.

Instead, obtain professional appraisals or use verified sales data from your area to support your case.

What If You Appeal for the Wrong Reason?

Appealing for the wrong reason can doom your case from the start. For instance, arguing that your property taxes are unaffordable or that the tax rate is too high does not address the core issue: the assessed value of your property.

Valid reasons for appealing include:

• Overvaluation compared to similar properties

• Incorrect property details, such as square footage or lot size

• Failure to apply applicable exemptions or incorrect classification

Focusing on legitimate grounds will give your appeal a better chance of success.

Contact a DuPage County, IL Property Tax Attorney

If you believe your property taxes are too high, do not risk making mistakes that could ruin your appeal. A Cook County, IL property tax appeal lawyer at Whitacre & Stefanczuk LTD can help you build a solid case and confidently navigate the appeal process. Call 773-622-6100 to schedule a free consultation and learn more about your rights and options.