Assessment ratio
The percentage of market value that becomes your assessed value.
States tax a fraction of value rather than all of it. The assessment ratio is that fraction — 100% in some states, 33.33%, 10%, or lower in others, and sometimes different for homes than for commercial property.
It matters for appeals because every comparison has to happen at the same level. A sale price is market value; an assessment is a ratio of it. Comparing them directly overstates or understates the gap by exactly the ratio.
It is also the source of a real appeal ground on its own: if similar homes are assessed at a lower effective ratio than yours, that is a uniformity claim, independent of what any of you would sell for.
Related
- Assessed value — The figure your county uses to calculate your tax — not what your house is worth.
- Uniformity — The requirement that similar properties be assessed alike — the strongest appeal ground.
- Market value — What a willing buyer would pay a willing seller, neither under pressure.
Property tax is state law and the details differ. For what applies where you live, see coverage by state and your appeal deadline.