On the notice
Look up if you are overpaying.
Why is taxable value lower than assessed value?
Because something was subtracted or frozen before millage was applied. The IAAO glossary defines taxable value as the appraised figure minus applicable partial exemptions or limits on valuation increases, and says property taxes are levied on that result. A homestead cut is the usual subtraction. A statutory cap is the usual freeze. Neither one rewrites the assessed headline; both change what the mills may touch.
Which number does a property tax appeal target?
The assessed value, which is the parent number. If that parent drops, the taxable slice often drops with it, unless a cap or exemption was already doing all the work. The property tax glossary and the homestead exemption page keep those levers in separate drawers. If FairAppeal does not file, or the appeal does not succeed, you owe nothing. The Fair Appeal review itself carries no upfront cost.