Assessment Ratio
The percentage of a property's fair market value that is used as its taxable assessed value for property tax purposes. Ratios vary by jurisdiction and property type.
The assessment ratio is the fraction of a property's actual market value that a local government uses as the assessed value for calculating property taxes. If a jurisdiction uses an assessment ratio of 80%, a home worth $500,000 on the open market would have an assessed value of $400,000, and taxes would be calculated on that lower figure.
Assessment ratios exist because many jurisdictions do not assess property at 100% of market value — either by law or practice. Ratios can differ by property class within the same jurisdiction; for example, residential property might be assessed at 70% of value while commercial property is assessed at 100%. This complicates direct comparisons of property tax burdens across jurisdictions.
Understanding your assessment ratio helps you evaluate whether your property is fairly assessed. If the ratio in your area is 80% and your assessed value divided by a recent comparable sale price is much higher than 80%, you may have grounds to appeal. Many states publish their legally required assessment ratios, and independent studies measure actual ratios to evaluate assessment uniformity and fairness.
How it works
The assessment ratio is the percentage of a property's actual market value that a local jurisdiction uses as the taxable assessed value. If a jurisdiction sets its assessment ratio at 75%, a home selling for $600,000 on the open market would carry an assessed value of $450,000 for tax purposes, and the local tax rate is applied only to that lower figure, not the full sale price.
You encounter the ratio directly on your annual property assessment notice, where it's used alongside the local tax rate to arrive at your bill. Ratios often differ by property type within the same jurisdiction — residential property might be assessed at a lower ratio than commercial property, for example — which makes comparing tax burdens across different jurisdictions or property classes trickier than it first appears, since a low rate on a high ratio can cost the same as a high rate on a low ratio.
The ratio is also a useful check on fairness: divide your assessed value by a recent comparable sale price in your area, and compare the result to your jurisdiction's published ratio. A result well above the published ratio is grounds to appeal your assessment, while a result close to it suggests your property is being assessed in line with everyone else's.
Example: checking a property against its assessment ratio
A home is assessed at $450,000 in a jurisdiction with a published 75% assessment ratio. The owner later finds a comparable nearby home sold for $580,000.
Dividing the assessed value by the comparable sale price gives $450,000 ÷ $580,000, or about 77.6% — close enough to the published 75% ratio that the assessment looks fair. Had that ratio come out to 95% instead, the owner would have solid grounds to appeal as over-assessed.
Frequently asked questions
What does a property assessment ratio actually do?
How can I tell if my property is fairly assessed?
Is the assessment ratio the same for every type of property?
Related Terms
Property Tax
An annual tax levied by local governments on the assessed value of real property (land and buildings). Rates and assessment methods vary widely by jurisdiction.
Homestead Exemption
A reduction in the assessed value (or taxable value) of a primary residence for property tax purposes. Most states offer homestead exemptions to owner-occupants, reducing their annual property tax bill.
SALT Deduction
An itemized deduction for state and local taxes paid, including income tax (or sales tax) and property tax. Under OBBBA (2025+), capped at $40,000 per return ($20,000 MFS) with phaseout above $500,000 MAGI to a $10,000 floor. Pre-OBBBA (2018–2024) the cap was $10,000 flat.