Basics
How Illinois assessments are built, where they go wrong, and what an owner can actually do about it. 105 articles, written to be useful to somebody who then does it themselves.
What an assessed value actually is
It is not a fact the county issued. It is an opinion produced by a model, and opinions can be wrong.
Basics · 4 min
Assessed value, market value, fair cash value: three different numbers
They are related by a ratio set in statute, and confusing them is the most common reason an appeal goes nowhere.
Basics · 3 min
The 33⅓% rule, and the counties it does not apply to
Illinois assesses at one third of fair cash value — except in Cook County, and except for farmland.
Basics · 3 min
The equalization factor, and why your assessment changed without anyone visiting
The state multiplier adjusts a whole county at once. It is not a reassessment, and it is not appealable.
Basics · 3 min
How your tax bill is actually calculated, step by step
Assessment × equalizer − exemptions × tax rate. Only one of those four is yours to argue with.
Basics · 3 min
Your assessment stayed flat and your bill still went up. Here is why
The levy moved, or the base shrank, or an exemption fell off. None of those are visible on your assessment notice.
Basics · 3 min
The levy: why your appeal does not cost the schools anything
Taxing bodies ask for a dollar amount, not a rate. Understanding that changes what an appeal actually does.
Basics · 2 min
Quadrennial reassessment: the year your number actually gets rebuilt
Most of Illinois reassesses every four years. Cook works on a three-year triad. Knowing your year changes your timing.
Basics · 2 min
Who actually set your value: township assessor, Supervisor of Assessments, or Board of Review
Three offices, three different jobs. Sending your argument to the wrong one wastes the only window you get.
Basics · 2 min
How to read your assessment notice
Four numbers and one date matter. The date is the one that ends your options.
Basics · 3 min
Your property class code, and why it decides who you get compared to
The class determines the pool of comparable properties. A wrong class quietly ruins every comparison.
Basics · 2 min
Uniformity: the argument that does not need an appraisal
The Illinois Constitution requires property to be taxed uniformly. That is a ground in its own right.
Basics · 3 min
Land and building are assessed separately, and only one may be wrong
Splitting the assessment splits the argument, and the land half is usually easier to win.
Basics · 2 min
Your PIN, and how to read it
The property index number encodes where your parcel sits. It is also the only identifier that is never ambiguous.
Basics · 2 min
Why two identical houses end up assessed differently
Not corruption. Model drift, stale records, and errors nobody has a reason to find.
Basics · 3 min