Preparing an evidence file for a property-assessment question
Learn how to organize documentation to effectively address questions or concerns regarding a property's assessment in the Illinois tax system.
The short answer
Preparing an assessment evidence file requires gathering documentation that supports a specific valuation, such as comparable market sales or evidence of significant property damage. Because property taxes are tied to EAV, having clear, documented facts ready before discussions with local officials is vital. Organize your file to contrast current assessment data with your independent findings regarding market value.
Gathering Property Data
Start by obtaining the official property record card from the county. This document outlines the physical characteristics of your home, such as square footage and room count.
Decision Worksheet: Compare the record card data to your actual home features. Note any discrepancies in square footage or bedroom count that could incorrectly inflate your valuation.
Identifying Comparable Evidence
Research recent sales of similar properties in your immediate neighborhood. Use these as benchmarks to see if your assessment aligns with current fair market conditions.
Hypothetical Planning: Create a spreadsheet tracking three similar homes nearby. Record their sale prices, lot sizes, and assessed values to determine if your property's assessment is disproportionately high.
Documenting Physical Condition
If your property has structural issues or lacks recent renovations, document these conditions. Photographs and professional repair estimates serve as evidence that the property value may be lower than assumed.
Decision Worksheet: List any major deferred maintenance items, such as a failing roof or foundation issues, and note the estimated cost of repairs for your evidence file.
Organizing Your File
Structure your file logically: property card, list of comparable sales, evidence of physical condition, and notes from any preliminary conversations with the assessor.
Decision Worksheet: Keep a 'Contacts Log' identifying the dates, names, and titles of any county officials you speak with regarding your file.
Checklist
- Obtain your official property record card from the county.
- Collect at least three comparable sales from your neighborhood.
- Take clear, dated photographs of any significant property defects.
- Compile repair estimates for any noted structural issues.
- Maintain a log of all interactions with government office staff.
Common questions
Does a private appraisal count as evidence?
A professional appraisal can be a strong piece of evidence, but ensure it adheres to standards acceptable by the local assessor's office for valuation inquiries.
What if my county's data is wrong?
If you find errors on your property record card, present the corrected information to your local assessor to request a review of the data.
Sources
- CFPB — Loan Estimate explainerChecked October 12, 2026
- CFPB — Closing Disclosure explainerChecked October 12, 2026
- Illinois Department of Revenue — Property tax overviewChecked October 12, 2026
- IRS Publication 523 — Selling Your HomeChecked October 12, 2026
This guide is general educational content from SQFT IO, prepared with AI assistance. It is not legal, tax or loan advice. Talk with a licensed attorney, tax professional or lender about your situation. SQFT IO Illinois license 478.027617.