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Blog · Evidence · 2026-08-03 · 2 min read

Adjusting comparables when nothing matches exactly

Small differences can be adjusted for. Large ones mean you picked the wrong comparable.

Perfect matches are rare. Small gaps can be handled honestly; large ones cannot be handled at all.

Adjust on a rate, not a guess

The cleanest adjustment is per square foot. If a comparable is 1,900 sq ft and yours is 2,000, compare assessed value per square foot rather than raw totals. That handles size without you inventing a dollar figure.

Adjustments a board will accept

Adjustments that will not survive

Unsupported percentages for "condition" or "updates". If you cannot show where a number came from, it reads as arithmetic invented to reach your conclusion, and it damages the comparables that needed no adjustment at all.

The honest rule

If a comparable needs more than one significant adjustment, it is not a comparable. Find another. Three properties needing no adjustment are worth more than ten you had to argue into shape.

This is general information about how Illinois assessments and appeals work. It is not legal advice, not an appraisal, and not a prediction about your case. Deadlines and rules differ by county — check yours with your Board of Review.

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How to find comparable properties for a tax appeal Start from the county's own records, not from what you know about the neighbourhood.What makes a comparable good enough to use Similarity on recorded attributes, proximity, and nothing clever. Four tight ones beat twenty loose.Using your county's parcel search like an assessor would Every Illinois county publishes a searchable roll. Most owners never open theirs.Assessed value per square foot: the number that makes comparisons possible Raw assessments cannot be compared. Rates can.

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