Many property owners focus on the amount due when a tax bill arrives. However, a concern about property taxes often begins earlier in the process, with the value assigned to the property by the assessing authority.

That assessed value may be based on property records, market data, building characteristics, income information, and other valuation factors. If the records are inaccurate or the assessment does not reflect the property’s fair value, condition, or treatment compared with similar properties, the owner may have grounds to request a review.

Property assessment appeals allow residential, commercial, and industrial property owners to present evidence and ask the appropriate taxing authority to correct an unfair or inaccurate assessment. Because the rules and filing periods can vary by county, owners should begin reviewing their assessment as soon as a notice becomes available.

Start With the Assessment, Not Just the Tax Bill

An assessment appeal is different from a complaint about local tax rates or how taxing districts use property tax revenue. The purpose of an appeal is to review the value or assessment level assigned to a specific parcel.

A higher tax bill does not necessarily mean that the assessor made an error. Tax bills may change because of local levies, tax rates, equalization factors, exemptions, and other components of the property tax system. An owner considering an appeal should identify whether the assessed value itself is unsupported or whether the property is being assessed unfairly compared with other properties.

Reviewing the assessment notice, property record, valuation history, and parcel information can help clarify where the concern begins.

Signs That an Assessment Deserves a Closer Look

Not every assessment increase provides grounds for an appeal. Certain issues, however, may justify a more detailed review.

The Property Description Is Incorrect

Assessors rely on property records that may include the size of the land, square footage of improvements, construction type, age, use, condition, and other physical characteristics.

An incorrect measurement, property classification, improvement description, or building detail may affect the assigned value. Owners should compare the official record with the property’s actual characteristics and document any meaningful differences.

The Assessed Value Appears Higher Than the Market Supports

An assessment may deserve review if the implied market value appears inconsistent with a recent arm’s-length sale, a professional appraisal, or reliable market evidence.

A sale price alone does not always establish the correct assessment. The transaction must be examined to determine whether it reflects normal market conditions and whether real estate, personal property, financing terms, or other considerations influenced the price.

Similar Properties Appear to Be Assessed Differently

Illinois law requires assessments to be fair and uniform. A property owner may have grounds for an appeal if comparable properties are assessed at lower levels without a reasonable explanation for the difference.

Meaningful comparisons should account for location, property type, size, use, age, construction, condition, and other valuation factors. A neighboring property is not automatically comparable simply because it is nearby.

The Assessment Does Not Reflect Current Property Conditions

Physical damage, substantial vacancy, demolition, functional limitations, environmental concerns, or changes in use may affect value. If the assessment data does not reflect those conditions, the owner may need to provide documentation explaining their impact.

The condition should be supported with dated photographs, reports, repair estimates, occupancy information, or other reliable records. General statements about a property’s problems may not be enough to establish a lower value.

Build the Appeal Around a Clear Basis

Effective property assessment appeals begin with a specific reason for requesting relief. The Illinois Department of Revenue identifies several possible concerns, including inaccurate property information, assessments that exceed those of similar properties, and assessments above the prevailing level within the jurisdiction.

The appropriate basis may include:

• Overvaluation based on market evidence
• Lack of uniformity compared with similar properties
• Incorrect property characteristics or measurements
• Improper classification or use information
• Failure to account for documented property conditions
• Errors affecting the assessed value
  
  

An appeal can include more than one argument, but each position should be supported by relevant evidence. Submitting a large collection of unrelated documents may make it harder for the reviewing authority to understand the issue.

Gather Evidence Before the Filing Period Closes

The type of evidence needed depends on the property and the reason for the appeal. Owners should gather records early enough to review them for accuracy and consistency.

Property Records and Assessment History

The current property record card, assessment notice, parcel information, and prior assessment history provide a starting point. These documents can help identify changes in value, classification, building data, or assessment methodology.

Owners should also verify the property index number and make sure the appeal is being filed for the correct parcel or group of parcels.

Market and Comparable-Property Information

Recent sales, professional appraisals, property listings, transfer records, and comparable assessments may help support a valuation or uniformity argument.

Comparable properties should be selected based on relevant characteristics rather than assessment amount alone. The appeal should explain why each property is comparable and address differences that may affect value.

Photographs and Condition Reports

Clear, dated photographs can document deterioration, structural problems, obsolete features, access limitations, unfinished improvements, or other conditions that may not appear in the official record.

Engineering reports, inspection findings, environmental records, repair estimates, and contractor documentation may provide additional support if the condition materially affects the property’s utility or value.

Income Records for Revenue-Producing Property

For commercial, industrial, or multi-unit properties, rent rolls, leases, vacancy records, and operating statements may be relevant. The records should correspond with the correct assessment period and comply with the filing authority’s requirements.

Owners should carefully review financial information before submission. Incomplete or conflicting figures can raise questions and weaken the presentation.

Pay Close Attention to Appeal Deadlines

Property assessment appeals are controlled by filing periods. Missing the deadline may prevent an owner from challenging the assessment for that tax year, even if the underlying concern is legitimate.

In Cook County, appeal periods are generally organized by township, and the Assessor publishes an official assessment and appeal calendar. Other counties, including DuPage, Lake, Will, and Kane, maintain their own schedules, forms, and procedural requirements.

Owners should not assume that the deadline begins with the arrival of the final tax bill. The filing period may be connected to the publication or mailing of assessment information. Reviewing notices promptly provides more time to investigate the property and prepare supporting evidence.

Understand the Levels of Review

The path for an assessment appeal depends on the county and the current stage of the matter.

An owner may begin by contacting the local assessor or assessment office to discuss a factual error or valuation concern. If the assessment books are still available for correction, some issues may be addressed without a formal appeal.

A formal written complaint may then be filed with the county board of review. The filing must follow the board’s rules and include the required forms and supporting materials.

According to the Illinois Department of Revenue, a formal appeal to the county board of review is generally required before an owner can pursue further review through the Illinois Property Tax Appeal Board or the circuit court. Owners must continue paying property taxes while an appeal of the board’s decision is pending.

Every level of review has its own deadlines and procedural requirements. A strategy that may be effective during an assessor-level review may need to be revised or expanded for a board hearing, state appeal, or court proceeding.

What Happens After an Appeal Is Filed?

After filing, the assessing authority or reviewing board may evaluate the written evidence, request additional documents, or schedule a hearing. Some decisions are made from the submitted record, while other cases provide an opportunity for testimony or oral argument.

Property owners should retain copies of:

• The completed appeal forms
• Supporting evidence
• Filing confirmations
• Correspondence from the reviewing authority
• Requests for additional information
• Hearing notices
• The final written decision

Keeping a complete file is especially important if the owner later considers another level of appeal. The grounds presented, evidence submitted, and procedural history may affect the available options.

The Value of Legal Guidance During an Assessment Appeal

Property assessment appeals can involve valuation methods, local rules, statutory requirements, and detailed factual records. A real estate tax attorney can help determine whether the assessment presents a supportable appeal and which evidence is most relevant.

Legal counsel may assist by:

• Reviewing assessment and parcel records
• Identifying factual or classification errors
• Evaluating possible valuation and uniformity arguments
• Organizing appraisals, financial records, and comparable data
• Preparing required appeal forms and supporting statements
• Representing the owner before administrative taxing bodies
• Evaluating options after an unfavorable decision

An attorney can also coordinate with appraisers, accountants, property managers, brokers, engineers, and other professionals whose information may be necessary to explain the property accurately.

The goal is not simply to submit paperwork. It is to present a focused position that connects the requested assessment change to reliable evidence and applicable legal standards.

Discuss Your Property Assessment With an Experienced Illinois Law Firm

McTigue & Associates, Taxpayer’s Advocate, is a family-owned Illinois real estate law firm with more than 40 years of experience handling real estate taxation matters. The firm represents residential, commercial, and industrial property owners before state and local taxing bodies and in Illinois state courts.

If you have questions about an assessment in Cook, DuPage, Lake, Will, or Kane County, contact McTigue & Associates to request a review. Acting early gives the legal team more time to examine the property records, identify possible appeal grounds, gather evidence, and confirm the filing requirements for your jurisdiction.

This article is for general informational purposes and does not constitute legal advice. Reading this article or contacting the firm does not establish an attorney-client relationship.