Last updated 2026-07-09
TL;DR
A mill rate (also called a millage rate) is the amount of property tax you owe per $1,000 of your property's assessed value. Multiply your assessed value by the mill rate, then divide by 1,000, to get your annual tax bill. Rates vary widely by jurisdiction, commonly running from about 5 mills to over 50 mills depending on state, county, and local levies.
What does mill rate mean, exactly?
A mill is one-thousandth of a dollar. So one mill equals $1 of tax for every $1,000 of assessed value. The word comes from the Latin "millesimum," meaning one-thousandth. Your property tax bill is the product of three numbers: your assessed value, the assessment ratio (sometimes called the equalization factor), and the mill rate.
The basic formula looks like this:
Annual tax = (Assessed Value × Mill Rate) ÷ 1,000
Say your home's assessed value is $300,000 and your total mill rate is 20. Your annual tax is ($300,000 × 20) ÷ 1,000 = $6,000. Simple enough on its face. The real-world version is messier, because you're almost never paying a single mill rate. You're paying a stack of rates layered on top of each other: county, municipality, school district, special districts, and sometimes a community college or flood-control authority.
Mill rates go by a few names depending on where you live. You'll see "millage rate" in Georgia, Florida, and much of the South. Some states call it a "tax rate" expressed per $1,000. Pennsylvania calls the levy a "real estate tax millage." The math is identical regardless of the label.
How is a mill rate calculated and who sets it?
Mill rates are set every year through a budget process, not a property value process. Here's the sequence:
1. Each taxing authority (the school board, the county commission, the city council) adopts a spending budget. 2. They subtract all non-property-tax revenue (state aid, fees, grants). 3. Whatever remains is the levy, meaning the total dollars they need to collect from property owners. 4. The assessor's office certifies the total assessed value of all taxable property in the jurisdiction, called the tax base or the grand list. 5. The mill rate is the levy divided by the tax base, scaled to per-$1,000 terms.
Formula: Mill Rate = (Total Tax Levy ÷ Total Assessed Value) × 1,000
If a school district needs to raise $50,000,000 and the total assessed value of property in the district is $2,500,000,000, the school mill rate is ($50,000,000 ÷ $2,500,000,000) × 1,000 = 20 mills.
This is why your mill rate can climb even when your assessed value stays flat. If the taxing authority grows its budget, or the overall tax base shrinks (think commercial vacancies after a plant closes), the rate rises to cover the gap. A fast-growing tax base does the reverse. Local governments can hold the mill rate steady and still collect more total revenue.
In most states, the governing body has to hold a public hearing before adopting a mill rate above a set threshold or above the prior year's rate. Florida's Truth in Millage (TRIM) law is a good example. It requires each taxing authority to mail every property owner a detailed notice showing the proposed millage and the public hearing dates before the rate is finalized. [1]
What's a typical mill rate in the United States?
There's no single national average that means much, because a mill rate only makes sense next to the assessment ratio. A 100-mill rate in a state that assesses property at 10% of market value produces the same effective tax as a 10-mill rate in a state that assesses at 100% of market value.
So compare effective rates instead. Effective rate means tax paid as a percent of market value, which puts every state on the same footing. The figures below come from the Tax Foundation's analysis of U.S. Census Bureau data. [2]
| State | Effective Property Tax Rate (%) | Approx. Mill Rate Equivalent |
|---|---|---|
| New Jersey | 2.23% | ~22.3 mills on market value |
| Illinois | 2.08% | ~20.8 mills |
| Connecticut | 1.79% | ~17.9 mills |
| Texas | 1.60% | ~16.0 mills |
| Nebraska | 1.54% | ~15.4 mills |
| National Median | ~1.10% | ~11.0 mills |
| California | 0.75% | ~7.5 mills |
| Colorado | 0.51% | ~5.1 mills |
| Alabama | 0.41% | ~4.1 mills |
| Hawaii | 0.31% | ~3.1 mills |
States that tax a higher share of market value tend to run lower nominal mill rates, and the reverse holds too. So when your cousin in another state mentions their millage, you can't compare it to yours without knowing both jurisdictions' assessment ratios.
Within a single state, the spread can be enormous. In Georgia, 2023 mill rates ran from roughly 8 mills in some suburban counties to over 40 mills in parts of Atlanta, depending on the combined county, city, and school levies. [3] Gwinnett County publishes its full millage breakdown every year so residents can see each component. See: [gwinnett county tax assessor]
How do assessment ratios change what you actually pay?
The mill rate applied to your assessed value is not the same as the rate applied to your market value. The gap between those two numbers is your state's assessment ratio.
Some states assess at 100% of market value. California uses the purchase price as the base under Proposition 13, then caps annual increases at 2%. [4] Others assess at a fraction. Georgia counties assess at 40% of fair market value by statute. [3] Indiana runs a trending system that also lands on a percentage of market value.
If Georgia's assessment ratio is 40% and your home's market value is $400,000, your assessed value is $160,000. A county mill rate of 10 produces a tax of ($160,000 × 10) ÷ 1,000 = $1,600, not $4,000. That 10-mill rate on assessed value works out to only 4 mills on market value.
Calculate your effective tax rate whenever you're comparing properties or sanity-checking your bill:
Effective rate = Annual tax ÷ Market value
For los angeles county property tax purposes, California's base rate is 1% of assessed value under Proposition 13, which is 10 mills, plus voter-approved debt levies that typically add another 0.15% to 0.35% depending on the parcel. [4]
The Lincoln Institute of Land Policy runs the 50-State Property Tax Comparison Study each year. It's the cleanest source I know of for comparing effective rates across jurisdictions, because it normalizes for both mill rates and assessment ratios. [5]
What does a mill rate look like on an actual tax bill?
Most tax bills list each taxing authority on its own line, with its separate mill rate and the resulting dollar charge. A typical suburban homeowner might see something like this:
| Taxing Authority | Mill Rate | Tax on $200,000 Assessed Value |
|---|---|---|
| County General Fund | 5.50 | $1,100 |
| County Schools | 14.25 | $2,850 |
| Municipality | 8.00 | $1,600 |
| Community College District | 0.75 | $150 |
| Fire District | 1.00 | $200 |
| Total | 29.50 | $5,900 |
The school district levy is usually the biggest slice, often 50% to 70% of the total bill. That's why school board budget votes hit homeowners so hard.
Some counties, like Cook County in Illinois, run a more complicated calculation that layers an equalization factor (the state multiplier) on top of the local assessment. See: [cook county tax assessor tax bill] The Illinois Department of Revenue certifies an equalization factor each year to bring assessed values closer to 33.33% of market value across counties. [6] That multiplier changes your effective mill rate even when the nominal rate holds steady.
In Bexar County, Texas, you won't see "mills" at all. Texas expresses rates as dollars per $100 of assessed value, which is mathematically the same as mills divided by 10. A rate of $0.35 per $100 equals 3.5 mills. See: [bexar county tax assessor]
Can a mill rate go up without a vote, and are there legal limits?
It depends heavily on state law, and the rules are genuinely complicated.
Many states have some form of statutory cap or rollback mechanism. In Michigan, the Headlee Amendment (Article IX, Section 31 of the Michigan Constitution) requires that if property values rise faster than inflation, the mill rate automatically rolls back to prevent a windfall tax increase without voter approval. [7] That's a hard constitutional floor.
Florida's TRIM process works differently. If a taxing authority wants to collect more total revenue than the prior year (adjusted for new construction), it has to hold a special hearing and call the move a tax increase rather than just a millage adjustment. The statute requires that "each taxing authority shall...advise the property appraiser of its proposed millage rate" and mail notice before adoption, at least 65 days before the fiscal year begins. [1]
California's Proposition 13 caps the base levy at 1% of assessed value and limits assessed value increases to 2% per year absent a sale or new construction. [4] Voter-approved bonds can push the effective rate above 1%, but those need a two-thirds supermajority.
Texas caps the year-over-year growth in total tax revenue for most local governments at 3.5% (cities and counties) or 2.5% (school districts) before requiring voter approval. [8]
What all these mechanisms share is that they shift the fight from "what is the mill rate" to "what is the total levy." Governments can hold the rate flat, let the tax base grow, and collect more money. Or they can nudge the rate up while budget caps technically allow it. Neither scenario needs your vote.
If you think your taxing authority blew past a statutory cap, that's a legal challenge, separate from a property value appeal. You'd contact your state department of revenue or a property tax attorney.
How does the mill rate affect whether you should appeal your assessment?
The mill rate is the multiplier on your assessment. A higher mill rate means every dollar of overassessment costs you more in tax, so an appeal in a high-mill-rate jurisdiction pays off bigger.
Here's the dollar picture. Suppose the assessor values your home $50,000 above what comparable sales say it's worth.
| Total Mill Rate | Annual Tax Overcharge | 3-Year Loss |
|---|---|---|
| 10 mills | $500 | $1,500 |
| 20 mills | $1,000 | $3,000 |
| 30 mills | $1,500 | $4,500 |
| 40 mills | $2,000 | $6,000 |
That table is exactly why paying a 30% to 40% contingency fee to an appeal firm (a common model) doesn't always add up. At 30 mills, a $50,000 overassessment costs you $1,500 a year. Winning the appeal saves you $1,500 a year. A firm keeping 35% takes $525 of that first-year savings. If you build and file the appeal yourself with a solid comparable-sales packet, you keep all of it.
TaxFightBack's DIY appeal kit walks you through that process: pulling the right comparable sales, formatting the evidence, and filing on time without handing anyone a cut of the savings.
Your first move before appealing is confirming the mill rate (or rates) for your parcel. Look for "millage rate," "tax rate schedule," or "levy schedule" on your county assessor's or auditor's website. Most counties post the current year's breakdown by taxing district.
How do mill rates differ for commercial vs. residential property?
The mill rate itself usually doesn't change by property type within a jurisdiction. The same millage schedule applies to a warehouse and the house next door. What changes is the assessment ratio and, in some states, the classification.
Minnesota uses a tiered classification system where different property classes carry different "class rates" that multiply assessed value before the mill rate hits. [9] A commercial property in Minnesota might carry a class rate of 1.5%, meaning 1.5% of its market value becomes the tax base before millage applies, while a residential homestead might sit at 1.0% for the first $500,000. Same mill rate, different effective tax per dollar of market value.
In Chicago and Cook County, commercial and industrial property is assessed at a higher share of market value (25%) than residential property (10%), which produces higher effective taxes for commercial owners at the same mill rate. [6]
If you own commercial property in a high-classification state, the mill rate conversation gets complicated fast. For St. Louis area commercial owners, st louis county personal property tax also comes into play, because business personal property is taxed separately.
For residential homeowners, the tool that sits alongside the mill rate is making sure every exemption you qualify for is applied. A homestead exemption that shaves $50,000 off assessed value in a 20-mill jurisdiction saves $1,000 a year before you ever touch the appeal process.
Where can you find your actual mill rate right now?
Your tax bill should list the mill rate, or enough information to calculate it. Lost the bill? Here's where to look.
For Georgia counties, your notice of assessment and your tax bill both list the millage by authority. The Georgia Department of Revenue keeps a millage rate archive going back multiple years. [3] Counties like Madison County, Coweta County, and Cherokee County post their adopted millage rates on their tax assessor sites. See: [madison county tax assessor, coweta county tax assessor, cherokee county tax assessor]
For Arizona, Maricopa County publishes a full tax rate table each year broken down by tax area code. Every parcel has a tax area code on the assessment notice. You match that code to the table. See: [maricopa property tax]
For Illinois' Lake County, the county clerk publishes the equalized assessed value and each taxing district's rate extension after the state multiplier is applied. See: [lake county property tax]
For San Diego, California, the Auditor-Controller publishes the Secured Tax Rate Area Factors each year, which is the county's master list of combined rates by area. See: [san diego property tax]
Can't find the rate directly? Do this: take your actual tax bill amount, divide by your assessed value, and multiply by 1,000. That gives you last year's effective combined mill rate.
Effective mill rate = (Annual Tax ÷ Assessed Value) × 1,000
For Bibb County, Georgia residents, the tax assessor site publishes the digest and current millage after the board adopts it each summer. See: [bibb county tax assessor]
Does a lower mill rate always mean lower taxes?
No, and this trips up a lot of homeowners who move between states.
The mill rate tells you nothing on its own. It means something only next to the assessment ratio and your property's market value. A county with a 50-mill rate that assesses property at 30% of market value has an effective rate of 1.5% of market value. A county with a 10-mill rate that assesses at 100% has an effective rate of 1.0%. The 50-mill county actually taxes equivalent property values less.
Exemptions are the other wrinkle. A state might carry a sky-high nominal mill rate but a generous homestead exemption that carves the first $100,000 or $200,000 off assessed value. Florida provides a $50,000 homestead exemption from assessed value for qualifying primary residences. [10] At a 20-mill rate, that exemption alone saves a homeowner $1,000 a year.
The number to track is your effective tax rate: total annual tax divided by your home's market value. That's the only clean comparison across jurisdictions. The Lincoln Institute study mentioned earlier is the standard academic reference for it. [5]
What happens to your mill rate when your assessed value goes up?
Mathematically, the mill rate and your assessed value are separate levers. Your assessed value rising does not automatically change the mill rate. The rate comes out of the budget process, not out of individual assessments.
Here's what often happens in practice. Widespread assessment increases across a county (say, from a reassessment year) can push total county assessed value up sharply. If the taxing authority doesn't cut the mill rate proportionally, property owners collectively pay more total tax than the year before. Some states require the authority to roll the rate back to a "revenue-neutral" level in that case. Others don't.
Michigan's Headlee rollback is one of the clearest examples of a legally required rate reduction when the tax base grows. [7] Minnesota's Truth in Taxation requires a notice and hearing but doesn't mandate a rollback. [9]
When you get a reassessment notice with a big jump in value, ask two questions, not one. Did they assess me fairly? And what's this year's mill rate compared to last year's? If both went up, that's a double hit. If the rate dropped because the county rolled it back, you might owe less despite the higher assessed value.
The practical check: multiply last year's assessed value by last year's mill rate, then multiply this year's assessed value by this year's mill rate. Compare the two products. That's your actual year-over-year tax change from the assessment, before any exemption changes.
Frequently asked questions
What is 1 mill in dollars?
One mill equals $1 of property tax per $1,000 of assessed value. So if your property is assessed at $250,000 and your total mill rate is 1, you owe $250. At a more typical combined rate of 20 mills, you'd owe $5,000. The word "mill" comes from the Latin for one-thousandth.
Is millage rate the same as mill rate?
Yes, they mean exactly the same thing. "Millage rate" is more common in Southern states like Georgia and Florida. "Mill rate" is more common in the Northeast and Midwest. Both describe the property tax rate expressed in units of $1 per $1,000 of assessed value. The calculation and the legal effect are identical.
How do I calculate my property tax from the mill rate?
Multiply your assessed value by the mill rate, then divide by 1,000. Example: assessed value of $180,000 times a 25-mill rate, divided by 1,000, equals $4,500 annual tax. If your state uses an assessment ratio (say 40%), apply that first: market value times the ratio gives you assessed value, then run the mill rate formula.
Who has the highest mill rates in the United States?
High nominal mill rates are common in states with low assessment ratios. Detroit, Michigan has run combined mill rates above 60 mills for some residential parcels, though Michigan assesses at 50% of market value. New Jersey's rates often top 20 to 25 mills on 100% assessed value, which makes it one of the highest effective-rate states in the country, per Tax Foundation data.
Can I fight my mill rate if I think it's too high?
Not through a standard property tax appeal. Your appeal targets the assessed value of your specific property, not the mill rate set by the taxing authority. To challenge a rate, you'd have to argue the government exceeded a statutory cap, violated a constitutional limit like Michigan's Headlee Amendment, or skipped required public notice. That's a legal or political process, not an assessment appeal.
Does the mill rate change every year?
It can, and it often does. Taxing authorities set mill rates annually through their budget process. The rate goes up if the budget grows faster than the tax base, and it can fall if the tax base expands sharply or the budget shrinks. Some states cap annual increases; others don't. Always check the current year's adopted rate rather than assuming last year's still applies.
What is a rollback mill rate?
A rollback rate is the mill rate that would produce the same total tax revenue as the prior year, adjusted only for new construction. If the taxing authority adopts a rate above the rollback rate, it's effectively raising taxes. Florida's TRIM law and Texas's revenue cap rules both use a rollback concept to trigger extra public notice or voter approval.
How does a homestead exemption interact with the mill rate?
A homestead exemption reduces your taxable assessed value before the mill rate is applied. If your home is assessed at $300,000, you have a $50,000 homestead exemption, and your mill rate is 20, your tax is ($250,000 × 20) ÷ 1,000 = $5,000, not $6,000. The mill rate itself doesn't change. The base it's applied to shrinks, so the savings grow with higher mill rates.
Why is my effective tax rate different from my neighbor's even though we have the same mill rate?
Your assessed value is probably different. If your neighbor bought their house in a state like California under Proposition 13's purchase-price assessment, and they bought 20 years ago, their assessed value can sit far below yours on a similar home. Same mill rate, very different assessed values, very different bills. Exemptions like senior freezes can also produce different effective rates at identical mill rates.
How often do counties reassess property, and how does that affect the mill rate?
Reassessment cycles vary widely: annually in many states, every 3 to 4 years in others, and only on sale in California. When a county does a mass reassessment and values rise sharply, state law sometimes requires a mill rate rollback to keep total collections revenue-neutral. Without that requirement, a reassessment year can mean both a higher assessment and an unchanged or rising rate.
What's the difference between a mill rate and an assessment ratio?
The assessment ratio is the percentage of market value used as the tax base. The mill rate is the tax rate applied to that base. They work together. A 40% assessment ratio with a 25-mill rate produces an effective rate of 1.0% of market value. A 100% ratio with 10 mills also produces 1.0%. You need both numbers to know your real tax burden.
Where do I find my county's current mill rate?
Start with your most recent tax bill. It usually lists each taxing authority's rate. If you need the current year before billing, check your county assessor, auditor, or clerk website for a "millage rate schedule," "tax rate table," or "levy schedule." Georgia's Department of Revenue archives millage rates statewide. Florida TRIM notices mailed in August each year show proposed and adopted rates.
Do commercial properties have a different mill rate than homes?
Usually the same mill rate applies to all property types in a jurisdiction, but many states apply different assessment ratios or classification multipliers to commercial versus residential property. In Cook County, Illinois, commercial property is assessed at 25% of market value versus 10% for residential, so the same mill rate produces higher effective taxes for commercial owners. Minnesota uses explicit class rates by property type.
If I win a property tax appeal, does the mill rate change for next year?
No. Winning an appeal lowers your assessed value, not the mill rate. The taxing authority applies the same rate to your lower assessed value, so your tax drops. If your appeal cuts your assessed value by $60,000 and your mill rate is 20, your annual savings are $1,200. The rate is set independently and applies uniformly across all parcels in that taxing district.
Sources
- Florida Department of Revenue, Truth in Millage (TRIM) process overview: Florida's TRIM law requires taxing authorities to notify property owners of proposed millage rates and hold public hearings before adoption; the notice process begins at least 65 days before the fiscal year begins.
- Tax Foundation, State and Local Property Tax Collections / Effective Rates analysis: State-by-state effective property tax rates based on U.S. Census Bureau data, showing New Jersey at approximately 2.23%, Illinois at 2.08%, and Hawaii at 0.31% as national extremes.
- Georgia Department of Revenue, Local Government Services, Millage Rates: Georgia counties assess property at 40% of fair market value by statute, and the Department archives annual millage rates for all county and city taxing authorities statewide.
- California State Board of Equalization, Proposition 13 overview: Proposition 13 caps the base property tax rate at 1% of assessed value (the purchase price) and limits annual increases in assessed value to 2% absent a sale or new construction.
- Lincoln Institute of Land Policy, 50-State Property Tax Comparison Study: Annual study normalizing property tax burdens for both mill rates and assessment ratios across all 50 states, enabling apples-to-apples effective rate comparisons.
- Illinois Department of Revenue, Property Tax Statistics and Equalization: Illinois certifies an annual equalization factor for each county to bring assessed values to 33.33% of market value; Cook County assesses commercial property at 25% and residential at 10% of market value.
- Michigan Constitution, Article IX Section 31 (Headlee Amendment), via Michigan Legislature: Michigan's Headlee Amendment requires automatic mill rate rollbacks when property value growth exceeds the rate of inflation to prevent windfall revenue increases without voter approval.
- Texas Comptroller of Public Accounts, Property Tax Basics: Texas caps year-over-year total tax revenue growth at 3.5% for cities and counties and 2.5% for school districts before requiring voter ratification; Texas expresses rates as dollars per $100 of value rather than mills.
- Minnesota Department of Revenue, Property Tax Division, Classification Rates: Minnesota applies statutory class rates by property type before the mill rate is applied, with commercial property at a higher class rate than residential homestead, and requires Truth in Taxation notices for proposed levy increases.
- Florida Department of Revenue, Homestead Exemption: Florida provides a $50,000 homestead exemption from assessed value for qualifying primary residences, reducing the taxable value before millage rates are applied.