This glossary names the words on a 2026 property tax notice and flags which ones actually change the bill: assessed value, taxable value, and millage.
A property tax glossary is a map of the words on a 2026 value notice, and the terms that actually move a bill are assessed value, taxable value, and millage. Other labels on the same sheet explain how the county got there. They do not set the dollar amount by themselves.
The IAAO Glossary for Property Appraisal and Assessment is the field's shared dictionary for those words. A property tax appeal, when one is filed, is aimed at the value under the rate, not at the school levy itself.
What is assessed value on a property tax bill?
Assessed value is the dollar figure the county assigns for tax purposes. It is not the market price, the listing price, or what a buyer would pay tomorrow.
The later millage multiplies this number.
Example: If the assessed value is $200,000, that $200,000 is the starting point for the yearly bill. A $400,000 sale does not replace it.
Market value is what the house would trade for. Assessed value is the tax figure on the notice. Some states print full market. Others print a fraction. The millage still starts from the printed figure.
Look up if you are overpaying.
What is a millage rate on a tax bill?
Millage is the local rate, written as mills, that turns a roll figure into a yearly tax.
Simply stated, one mill equals $1 of tax per $1,000 of the value being taxed.
One mill = $1 per $1,000
Example: 10 mills on $200,000 is $2,000 ($200,000 × 0.010 = $2,000). Twenty mills is the same idea as two percent.
Millage is not a percent of the listing price. City, school, and special-district mills can each land on the same home, so the printed rate is usually a stack.
What is the difference between taxable value and assessed value?
Taxable value is what remains after exemptions or caps are taken off the assessed figure. Assessed value is the parent number the county wrote first.
Those exemptions and caps sit between the two figures. The bill follows the taxable one.
Example: If the assessed value is $250,000 and a $50,000 homestead exemption applies, the taxable value is $200,000.
$250,000 assessed minus $50,000 homestead = $200,000 taxable
Ten mills on that $200,000 is $2,000, not $2,500. A property tax appeal aims at the parent assessed number, not at the exemption line.
What is mass appraisal of property?
Mass appraisal is how a county values every parcel on the roll together, as of one date, using the same data set and the same method.
Each parcel is one line in that county-wide pass. IAAO's Standard on Mass Appraisal of Real Property is the profession's write-up of that group process.
A notice can look wrong without the house changing because the run writes a new number for every parcel at once. A kitchen that was not remodeled still receives the neighborhood's new figure.
What is an equalization rate on a tax roll?
An equalization rate is a town-wide or county-wide ratio, not a knob on one house.
New York's Department of Taxation and Finance publishes the formula as municipal assessed value divided by municipal market value.
Total assessed value ÷ total market value = equalization rate
The state uses that percentage to split a school or county levy across towns that assess at different levels. A rate of 100 means full value in the state's math.
That official explainer is clear: the rate measures a whole town, not one house.
What is a property record card?
A property record card is the office file the assessor keeps on a parcel, and the notice is drawn from that file. IAAO's other name for that file is appraisal card.
Land value and improvement value often sit as two lines on that same file. Land is the lot as if vacant. Improvement is the building and other attachments.
The card is not the tax bill and not the deed. This page names what the card is. It does not walk a homeowner through opening or changing it.
What is a board of equalization?
A board of equalization is a separate panel that hears a challenge to the printed value. Some places stamp the same panel Board of Revision (BOR) or Board of Assessment Review (BAR).
The assessor wrote the number. This body is the later forum that can move it. IAAO files those local names under assessment review board.
Fair Appeal handles the case in front of that panel when a filing goes forward, and FairAppeal only collects a percentage of first-year tax savings if the tax actually drops.
What property tax terms should I look up first?
The first property tax terms to look up are assessed value, taxable value, and millage, because those three produce the bill.
Mass appraisal, the record card, the board of equalization, and informal versus formal appeal explain how the number got there and what happens next. Next lookups: assessment ratio, effective tax rate, levy, special assessment, tax roll, exemption versus appeal, assessment cap, escrow, protest versus appeal, fair market value, mill, CAMA, bill versus notice, parcel number, tax lien, personal property, assessor, overassessment, Zillow versus the roll, valuation date, yearly appeal, circuit breaker, supplemental assessment (CA), treasurer, taxing district, use-value, neighbor tax, sales ratio, abatement, appeal timing, lawyer, tentative roll, deferral, board of revision, grievance day (NY), cost approach, sales comparison, income approach, base-year value (CA), ownership change, new construction, appeal cost, certiorari (NY), clerical error, and escaped assessment.
What other property tax terms should I look up?
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