Last updated 2026-07-09
TL;DR
A mill rate (or millage rate) is the dollars of property tax charged per $1,000 of assessed value. Multiply your assessed value by the mill rate, then divide by 1,000. That number should match your tax bill. If it doesn't, your assessment or the rate applied to your property class may be wrong, and you have grounds to act.
What is a mill rate, exactly?
One mill equals $1 of tax for every $1,000 of assessed property value. A mill rate of 20 means you owe $20 for every $1,000 the assessor says your property is worth. The word comes from the Latin "millesimum," meaning thousandth.
Most counties publish their mill rates as a decimal: 20 mills is written as 0.020. Some jurisdictions call it a "millage rate" or a "tax rate per thousand." Same thing, different label.
Here's the part people miss. The mill rate is set by local governments, not by the assessor. Your city council, county board, or school district board votes on a budget every year, and the mill rate falls out of that math: take the total amount they need to raise from property taxes, divide by the total taxable assessed value in the jurisdiction, and you get the mill rate [1].
That distinction matters. A high tax bill can come from a high assessment, a high mill rate, or both. The fix is different depending on which one is the problem.
How do you calculate your property tax from the mill rate?
The formula is short:
Tax owed = (Assessed value ÷ 1,000) × Mill rate
Written the way most finance people do it:
Tax owed = Assessed value × (Mill rate ÷ 1,000)
Both produce the same number. Say your county assessor puts your home's assessed value at $280,000 and the total mill rate is 22.5 mills.
$280,000 ÷ 1,000 = $280 $280 × 22.5 = $6,300 in annual property tax
That's what your bill should show, before any exemptions are subtracted. If your bill is higher, something is off.
One thing trips people up: many states don't tax the full assessed value. They apply an "assessment ratio" or use a "taxable value" that's a percentage of full market value. Texas assesses at 100% of market value but caps how fast taxable value can rise [2]. California under Proposition 13 uses the purchase price plus a maximum 2% annual inflation adjustment rather than current market value [3]. In those states, confirm which value the mill rate is being applied to before you run the math.
Where do you find your county's mill rate?
Your annual property tax bill or assessment notice usually lists the mill rate, often broken out by taxing district. You might see separate lines for the county, the school district, the city, a fire district, and a library district, each with its own millage, all adding up to the total.
If the bill doesn't show it clearly, go to your county assessor's or treasurer's website. Nearly every county posts the current mill rate in a budget or levy document. Search for "[your county name] mill rate [year]" or "millage rate levy."
A few places to find this publicly:
- Cook County, Illinois publishes its tax rates by township on the Cook County Clerk's website [4].
- Hennepin County, Minnesota posts its levy and rate tables at the county auditor's page. See our Hennepin County property tax overview for the direct link.
- Gwinnett County, Georgia lists millage rates by city and school district on the tax commissioner's site [5].
- Bexar County, Texas breaks out the taxing unit rates on the Bexar Appraisal District site. More detail in our Bexar County tax assessor guide.
Still stuck? Call the county treasurer's office. They're usually easier to reach than the assessor and can read you the current rate in about a minute.
What is a typical mill rate across the United States?
Mill rates vary enormously, which is why comparing your rate to a neighbor in another state is close to useless. According to the Tax Foundation's analysis of Census Bureau data, effective property tax rates (which fold in both the assessment ratio and the mill rate) run from about 0.28% of home value in Hawaii to over 2.1% in New Jersey and Illinois [6]. Those effective rates are basically the mill rate expressed as a percentage of market value rather than assessed value.
Raw mill rates swing just as hard. You'll see numbers under 5 mills in some low-tax California districts (where Prop 13 caps the base rate at 1% of assessed value, or 10 mills) [3] and over 100 mills in parts of New Jersey and some Michigan cities where assessed values sit well below market.
High mill rates don't always mean high bills. A county might set a 90-mill rate but assess at 10% of market value, so the effective rate is 9 mills, or 0.9%. You need both the mill rate and the assessment ratio to know what you're actually paying.
How do you use the mill rate to catch a mistake on your tax bill?
This is the part that saves you money. You can audit your own bill in about 15 minutes.
Step 1: Get your assessed value. It's on your assessment notice or your county's property search portal. Write it down.
Step 2: Get the mill rate. Pull it from your bill or the county website. If there are multiple taxing districts, add them all up for a total.
Step 3: Check for an assessment ratio. If your state taxes a fraction of full value (say, 25% of market value), multiply the assessed value by that ratio first. Your state's department of revenue website lists this. In Illinois, the assessment ratio in most counties is supposed to be 33.33% of fair cash value [7].
Step 4: Run the formula. (Assessed value × assessment ratio) ÷ 1,000 × mill rate = tax before exemptions.
Step 5: Subtract your exemptions. A homestead exemption might cut your taxable value by a flat dollar amount. Illinois's general homestead exemption, for instance, reduces equalized assessed value by up to $10,000 in most counties [7]. Apply those reductions before comparing to your bill.
Step 6: Compare. If your calculated number is meaningfully lower than your bill, you have a discrepancy worth chasing. Common causes: the wrong property class got applied (commercial rate instead of residential), an exemption never landed, or your assessed value jumped incorrectly.
For big, complicated jurisdictions, our Cook County tax assessor tax bill and NYC property tax guides walk through the math in those famously tangled systems.
What's the difference between a mill rate and an effective tax rate?
The effective tax rate tells you how much of your home's market value you're actually paying in taxes each year. It's the mill rate adjusted for whatever assessment ratio your state uses.
Effective tax rate = Mill rate × Assessment ratio
If your mill rate is 50 mills and your state assesses at 25% of market value: 50 mills × 0.25 = 12.5 mills effective rate, or 1.25% of market value.
The Tax Foundation and most researchers use the effective rate when comparing property tax burdens across states, because raw mill rates mean nothing without knowing the assessment ratio [6]. When a politician says "we lowered the mill rate" but also raised assessed values, your bill can still climb. The effective rate is the honest measure.
California works differently enough to need its own explanation. Under Proposition 13, the base levy rate is capped at 1% of assessed value, and assessed value is pegged to purchase price with a maximum 2% annual increase [3]. Voters can approve local "override" levies on top of that. So your total effective rate might be 1.1% or 1.3% depending on your district, but the structure is unusual compared to most states. Our LA County property tax and Santa Clara property tax pages cover the California specifics.
Can the mill rate be different for different types of property?
Yes, though the mechanism varies by state. Some states set different mill rates outright for residential, agricultural, and commercial property. Others get to the same place by using different assessment ratios for different classes while keeping one mill rate.
Minnesota uses a tiered system where property types carry different "class rates" applied before the levy is calculated [8]. A residential homestead worth $500,000 gets classified differently than an apartment building worth the same, which produces a different tax bill even under the same mill rate.
New York City takes this further. It has four property classes with very different effective tax rates. Class 1 (one-to-three family homes) has historically been taxed at much lower effective rates than Class 2 (apartments) or Class 4 (commercial) [9]. That system has drawn legal challenges and reform fights for years. The NYC property tax article covers the current class rate structure.
Always check which property class your home is assigned. Misclassification as commercial or multi-family is a documented cause of inflated bills, and it's fixable.
What happens to your mill rate when property values rise across the board?
Plenty of homeowners got a crash course in this after 2020, when residential values spiked in many markets. In theory, if assessed values rise and the government needs the same amount of money, the mill rate should fall proportionally. In practice, local governments often hold rates flat or cut them by less than values rose, so bills go up.
Some states have truth-in-taxation laws that force local governments to advertise a "rollback rate," which is the mill rate that would raise the same total revenue as last year. To collect more, they have to hold a public hearing and vote explicitly to exceed it. Texas requires this under the Tax Code: the "no-new-revenue rate" and the "voter-approval rate" trigger public notice or an automatic election if exceeded [2].
Knowing whether your jurisdiction has a truth-in-taxation law, and whether officials stayed within it, tells you whether a rising bill is driven by your assessment going up or by a deliberate choice to collect more revenue.
For a county-level look at how this plays out with assessments, the Montgomery County property tax guide covers a high-value market where assessment growth has repeatedly outrun mill rate reductions.
How do you appeal if the mill rate seems correct but your bill is still too high?
If you've run the math, confirmed the mill rate, confirmed the assessment ratio, subtracted every exemption you qualify for, and your calculated tax matches the bill but the bill still feels wrong, the problem is almost certainly your assessed value, not the rate.
You don't appeal the mill rate. Rates are set by elected bodies through a public process. What you appeal is the assessed value the rate is applied to.
To win, you show the assessor's estimate of your property's market value is too high. That means gathering comparable sales (comps), a recent appraisal, or evidence of condition problems that drag the value down. Most counties set an appeal deadline of 30 to 90 days from when you receive your assessment notice, though it varies by state [10].
Here's what I'd do before paying anyone. A contingency firm takes 30 to 40% of any savings. TaxFightBack's DIY appeal kit walks through how to build a comp-based case, file the forms, and present at a board of review hearing for none of that cut. Even without the kit, the assessor's office is required to explain how they reached your assessed value. That one conversation sometimes clears up an obvious error on the spot.
For state-specific procedures, our Los Angeles County property tax and St. Louis County personal property tax guides cover local filing requirements in detail.
How do you find historical mill rates to see how yours has changed?
Historical mill rates come from the same county sources that post current rates, just archived. The county clerk, auditor, or treasurer often keeps rate tables going back 10 or more years. The catch is that many counties don't make this easy. You might have to request older documents by phone or under a public records request.
The Lincoln Institute of Land Policy runs a "Significant Features of the Property Tax" database that covers effective tax rates by state over time, which is the best academic source for long-term trend data [11]. It won't hand you your specific county's mill rate history, but it puts your jurisdiction in context.
To spot a sharp one-year increase, the math is quick: divide this year's mill rate by last year's, subtract 1, and that's the percentage change. A 10% jump in the mill rate stacked on a 15% jump in assessed value compounds to a 26.5% bill increase. That's the kind of one-two hit that blindsides homeowners who weren't watching either number.
What exemptions reduce the value before the mill rate is applied?
Exemptions cut your taxable assessed value before the mill rate is multiplied. A $50,000 homestead exemption at a 20-mill rate saves you exactly $1,000 a year ($50,000 ÷ 1,000 × 20). That's why you need both your exemptions and your mill rate. One without the other is half the picture.
Common exemptions that reduce taxable value:
- Homestead exemptions: Most states offer these to owner-occupants. Florida's runs up to $50,000 on assessed value [12]. Georgia's basic homestead exemption is $2,000 off assessed value for school taxes, with additional exemptions by county [13].
- Senior / age-based exemptions: Often larger than the basic homestead, sometimes with income limits.
- Veteran and disability exemptions: Many states exempt 100% of assessed value for 100% disabled veterans.
- Agricultural use exemptions: Property taxed on use value rather than market value.
To confirm you're getting every exemption you qualify for, check your assessment notice or county portal. If one is missing, most counties let you file a late application or apply for a correction. Deadlines for new exemption applications often fall between January 1 and April 1 of the tax year, but correction claims can sometimes be filed later.
For more on specific programs, our Gwinnett County tax assessor and Bibb County tax assessor guides cover Georgia's county-level exemption processes in detail.
Is paying your property tax bill online any different from paying by check?
No difference in legal effect. Both count as payment. Online payment is usually faster and gives you an immediate confirmation number, which helps if you ever need to prove you paid on time. Most counties take ACH bank transfer or credit card, though credit card payments usually carry a convenience fee of 2 to 3% of the bill.
Our online tax payment for property guide covers how to work payment portals, how to set up installment plans where they exist, and what to do if a payment gets lost or misapplied.
One thing I'll say straight: paying your bill on time does not waive your right to appeal your assessment. Those are two separate processes in nearly every state. Pay the bill, then fight the number.
Frequently asked questions
What does a mill rate of 10 mean in dollars?
A mill rate of 10 means you pay $10 for every $1,000 of assessed value. A home assessed at $300,000 with a 10-mill rate owes $3,000 in annual property tax before exemptions. To get your number: divide assessed value by 1,000, then multiply by the mill rate.
Is a higher mill rate always worse for homeowners?
Not necessarily. A high mill rate paired with a low assessment ratio can produce a lower effective tax rate than a low mill rate applied to full market value. What matters is the effective rate: the percentage of your home's actual market value you pay each year. Some high-mill-rate states have low effective rates because their assessed values are a small fraction of market value.
Who sets the mill rate in my county?
Local elected officials set it, not the assessor. Your county board, city council, school board, and any special districts (fire, library, transit) each set their own levy, which determines their slice of the mill rate. The assessor determines values; the governing bodies determine how much money they need. The mill rate is the output of dividing one by the other.
How often does the mill rate change?
Most jurisdictions set a new mill rate every year as part of the annual budget process. Some have rates that only change when a ballot measure passes. In states with strict levy limits, the mill rate adjusts automatically when total assessed values change, to prevent windfalls for local governments. Check your county's budget calendar; the new rate is usually set in late fall for the following tax year.
What is the difference between a mill rate and an assessment ratio?
The mill rate is the tax per $1,000 of taxable value. The assessment ratio is the percentage of market value at which property is assessed for tax purposes. Many states assess at something less than 100% of market value, so you must apply the assessment ratio before multiplying by the mill rate. The effective tax rate combines both into one number for clean comparison.
Can two neighbors with identical homes have different mill rates?
Yes, if they're in different taxing districts. Mill rates are set separately by every overlapping jurisdiction: county, city, school district, fire district, and more. A home just inside a city limit might pay a city levy that the home a block away, outside the limit, doesn't owe. This is common near municipal boundaries and is completely legal.
How do I know if my property class is correct, and why does it matter for my mill rate?
Your property class is listed on your assessment notice. Common classes are residential, commercial, agricultural, and industrial. In states or counties that apply different effective rates to different classes, being misclassified as commercial can mean paying a significantly higher rate. Call your assessor's office to confirm your class; if it's wrong, file a correction request or include it in your appeal.
Does a lower mill rate mean my taxes will go down next year?
Not automatically. If your assessed value rose more than the mill rate dropped, your bill goes up. Run the full calculation both years and compare. Many counties lower the mill rate modestly after a reassessment cycle precisely because values jumped, but not enough to offset the value increase. Always check the bill, more than the rate.
Where can I find the mill rate for a specific city or school district?
Start with your county assessor or treasurer's website. Most post rate tables by taxing jurisdiction. Your tax bill itself should list each district's rate separately. If you still can't find it, the county clerk's office maintains official levy documents and can provide the rate for any taxing body within the county. State department of revenue sites also sometimes aggregate this data.
If I win a property tax appeal and my assessed value drops, how does that affect my mill rate?
The mill rate stays the same. Only your taxable assessed value changes. Your savings equal the reduction in assessed value multiplied by the mill rate, divided by 1,000. For example, a $20,000 reduction at a 25-mill rate saves you $500 per year. The mill rate is applied to the whole jurisdiction; one successful appeal doesn't shift the rate for anyone else.
Are mill rates publicly available, or do I have to file a records request?
Mill rates are public information in every state. Most counties post them on the assessor, treasurer, or clerk's website without any request required. If you can't find them online, a simple phone call to the county treasurer usually gets you the number immediately. Formal records requests are rarely necessary for current or recent historical rates.
What is a rollback rate, and how is it related to the mill rate?
A rollback rate (called the "no-new-revenue rate" in Texas and similar terms elsewhere) is the mill rate that would raise the same total property tax revenue as the prior year, given current assessed values. If values rose 10%, the rollback rate is roughly 10% lower than last year's rate. Jurisdictions that set the rate above the rollback rate are effectively raising taxes, even if the mill rate itself looks similar to last year.
Sources
- Lincoln Institute of Land Policy, Significant Features of the Property Tax: Mill rates are derived by dividing a jurisdiction's required levy by total taxable assessed value in the tax base.
- Texas Comptroller of Public Accounts, Property Tax Basics: Texas Tax Code requires local taxing units to calculate and publish a no-new-revenue rate and voter-approval rate each year.
- California State Board of Equalization, Proposition 13 Overview: Under Proposition 13, the base property tax rate is 1% of assessed value (equivalent to 10 mills), and assessed value is pegged to purchase price with a maximum 2% annual increase.
- Cook County Clerk, Tax Extension and Rates: Cook County publishes tax rates by township and taxing district on the county clerk's website.
- Gwinnett County Tax Commissioner: Gwinnett County lists millage rates by city and school district on the tax commissioner's site.
- Tax Foundation, Property Taxes by State: Effective property tax rates on owner-occupied housing range from approximately 0.28% in Hawaii to over 2.1% in New Jersey and Illinois, based on Census Bureau data analysis.
- Illinois Department of Revenue, Property Tax Overview: Illinois statute sets the assessment ratio at 33.33% of fair cash value for most property, and the general homestead exemption reduces equalized assessed value by up to $10,000 in counties under 3 million population.
- Minnesota Department of Revenue, Property Tax Administration: Minnesota uses a tiered class rate system where different property types carry different classification rates applied before the levy, resulting in different effective tax burdens for residential homestead versus commercial or apartment properties.
- NYC Department of Finance, Property Tax Classes: New York City assigns property to four tax classes, with Class 1 one-to-three family homes historically taxed at much lower effective rates than Class 2 apartments and Class 4 commercial property.
- National Taxpayers Union Foundation, Property Tax Appeal Guide: Property tax assessment appeal deadlines typically range from 30 to 90 days from receipt of the assessment notice, varying by state and jurisdiction.
- Lincoln Institute of Land Policy, Significant Features of the Property Tax Database: The Lincoln Institute maintains multi-year effective tax rate data by state that researchers use to track long-term property tax burden trends.
- Florida Department of Revenue, Property Tax Information for Taxpayers: Florida's homestead exemption reduces assessed value by up to $50,000 for owner-occupant residential property.
- Georgia Department of Revenue, Property Tax Exemptions: Georgia's basic homestead exemption reduces assessed value by $2,000 for school tax purposes, with additional county-level exemptions available.