Mill rate explained: how your property tax bill is actually calculated

Last updated 2026-07-09

What is a mill rate and what does it mean for your property taxes?

One mill equals $1 of tax per $1,000 of assessed value. The word comes from the Latin "millesimum," meaning one-thousandth. So a mill rate of 20 means you owe $20 for every $1,000 your property is assessed at. On a home assessed at $300,000, that's $6,000 a year.

Most people read the bottom line on their tax bill and stop there. That's a mistake. The mill rate is the single number that connects your assessed value to the dollars you actually owe. It tells you whether your local government raised your taxes, whether your assessment is out of line with your neighbors, and whether you're paying the right amount at all.

The terms "mill rate" and "millage rate" are used interchangeably. You'll also see "tax rate" on some bills, which is usually just the mill rate expressed as a percentage or decimal (a 20-mill rate is 0.020 or 2.0%). All three phrases point to the same thing.

Here's the distinction that trips people up. The mill rate is set by your local taxing authority, not by your assessor. Your assessor decides how much your property is worth. Your county commissioners, school board, city council, and other taxing bodies then set the mill rate to raise the revenue they need. That separation matters enormously when you're deciding what to fight.

How is the mill rate calculated and who sets it?

Local governments work backward from a budget number. The taxing authority decides how much revenue it needs, subtracts non-property-tax income (grants, fees, state aid), and divides the remainder by the total assessed value of all taxable property in the jurisdiction. That ratio, expressed per $1,000, is the mill rate ^[1].

The formula looks like this:

Mill rate = (Tax levy needed / Total assessed value of all properties) x 1,000

Say a school district needs to raise $40 million and the total assessed value of all property in the district is $2 billion. The mill rate is ($40,000,000 / $2,000,000,000) x 1,000 = 20 mills.

In most states, multiple taxing bodies stack their rates on top of each other. The total mill rate on your bill is usually the sum of a county rate, a municipal rate, a school district rate, and sometimes a fire district rate, a library rate, and others. Connecticut publishes mill rates for every town that reflect all these layers combined ^[2]. Most homeowners are surprised at how many separate levies show up as line items.

Who sets each piece? School boards and county commissions usually have the most control. In many states, state law caps the maximum mill rate a local government can impose without a voter referendum. Michigan limits local millage increases through the Headlee Amendment, which requires voter approval for new or increased millages above the rate of inflation ^[3].

How do you calculate your property tax bill from the mill rate?

The math is simple once you know two numbers: your assessed value and your mill rate.

Property tax = (Assessed value / 1,000) x Mill rate

Or the same thing written differently:

Property tax = Assessed value x (Mill rate / 1,000)

A quick example. Your home has an assessed value of $250,000. Your combined mill rate is 28.5 mills.

($250,000 / 1,000) x 28.5 = $7,125 per year.

Some states add an "assessment ratio" or "equalization ratio," which is a percentage of market value used for tax purposes. If your state assesses at 80% of market value and your home is worth $300,000, the assessed value for tax purposes is $240,000. Apply the mill rate to that number, not the market value. Always check your assessment notice to see which number your county is actually using ^[4].

You can run this in reverse too. Take your actual tax bill, divide by your assessed value, multiply by 1,000, and you get your effective mill rate. If that number differs from what your county publishes, something on your bill is worth a closer look.

One note for the confused. Some people searching for a "feed rate calculator milling" or "milling machine feed rate formula" land on property tax articles by accident. Those are machining terms for a completely different industry. The "milling" here is strictly the taxation concept, not metal cutting. The feed rate formula for milling in manufacturing (feed rate = RPM x chip load x number of flutes) has nothing to do with property taxes.

What is a typical mill rate across the United States?

Mill rates vary more than most people expect, even inside a single state. The table below shows effective mill rates for selected counties based on recent data from the Lincoln Institute of Land Policy and state revenue department reports ^[5][6].

Jurisdiction	Approx. Effective Mill Rate	Notes
Honolulu County, HI	3.5 mills	Lowest major metro
Los Angeles County, CA	~11 mills	Prop 13 limits base
Maricopa County, AZ	~10-13 mills	Varies by city
Bexar County (San Antonio), TX	~22-26 mills	No state income tax offsets this
Cook County, IL	~60-80 mills (effective)	Among highest in U.S.
Camden City, NJ	~30 mills nominal, higher effective	Complex equalization

These are approximations. Cook County shows why nominal and effective rates diverge: the assessment ratio often sits far below 100%, so a high nominal mill rate partly corrects for low assessed values ^[7].

The Lincoln Institute found in its 2023 Significant Features of the Property Tax report that the median effective property tax rate nationally was about 1.1% of market value, which translates to roughly 11 mills at full assessed value ^[5]. That median hides an enormous spread. At the low end, Hawaii's effective rate runs around 0.28%. At the high end, parts of New Jersey and Illinois exceed 2.5%, or 25 mills at full value.

If your effective mill rate (from your own bill calculation) is dramatically higher than your neighbors' in similar communities, that's a signal. But the mill rate itself is rarely the problem. Usually your assessed value is inflated relative to your home's market value. The mill rate is the same for everyone in your tax district. The assessed value is where the inequality hides.

Why does your mill rate change from year to year?

Three things move the mill rate: budget changes, changes in the total assessed value of the tax base, and voter-approved levies.

If your city increases its budget and the total assessed value of all property stays flat, the mill rate goes up. If property values across the jurisdiction rise sharply (as they did in 2021 and 2022 in most U.S. markets), the total assessed value of the base grows, which mathematically pushes the mill rate down even if spending stays constant. That's why in hot real estate markets, assessors often raise individual assessments while the mill rate drops a bit, and your bill still climbs.

Voter-approved bond measures and millage elections add new mills on top of the base rate. School districts frequently go to voters for construction bonds that show up as separate millage line items for 20 or 30 years ^[3].

Truth-in-taxation laws in several states require local governments to advertise a "rollback rate," the mill rate that would produce the same total revenue as last year even after reassessment. Any rate above the rollback is treated as a tax increase requiring public notice and sometimes a vote. Texas has had this mechanism since 2019 under Senate Bill 2, which caps the no-vote revenue increase at 3.5% for most taxing units ^[8]. Georgia has a similar truth-in-taxation requirement ^[9].

If you see your mill rate drop while your assessment jumps, do the math on your actual bill. A lower mill rate does not guarantee a lower bill.

How does the mill rate interact with exemptions?

Exemptions cut the taxable portion of your assessed value before the mill rate touches it. A homestead exemption of $50,000 on a $300,000 assessed value leaves $250,000 subject to the mill rate. At 20 mills, that's $1,000 a year in savings.

Some exemptions are a flat dollar amount. Others are a percentage of assessed value. Senior freeze programs in states like Illinois lock your assessed value at a fixed base year, which means rising mill rates eat into less of your equity ^[10]. Veterans' exemptions, disability exemptions, and agricultural use exemptions all reduce the base to which the mill rate applies.

The interaction can get subtle. Some jurisdictions apply different mill rates to different classes of property. Many states tax commercial property at a higher assessment ratio than residential property, which means commercial owners face a higher effective mill rate even when the nominal rate is the same. Minnesota has a tiered class rate system where different property types have different class rates applied before the mill rate calculation ^[11].

If you're eyeing a neighboring commercial property to compare assessments, remember the class difference. A commercial building assessed at the same dollar amount as your home may be facing a genuinely higher effective tax rate, not an error.

Can a high mill rate be grounds for a property tax appeal?

No. The mill rate is set by elected officials and can't be appealed through the assessor's office or the board of equalization. You can't sit at a hearing and argue the mill rate is too high. Your recourse on the mill rate is political: attend public hearings, vote on millage referenda, or elect different officials.

What you can appeal is your assessed value. That's where most legitimate tax savings come from for residential homeowners.

Here's the logic. If your assessed value is $350,000 but your home's market value is really $290,000, and your mill rate is 25, you're paying ($350,000 / 1,000) x 25 = $8,750 instead of ($290,000 / 1,000) x 25 = $7,250. That's $1,500 a year you're overpaying, and you'd get it back by winning an appeal to reduce your assessed value to market value. The mill rate stays the same. The base changes.

The appeal process needs evidence: comparable sales, an independent appraisal, or documentation of errors in your property record (wrong square footage, extra bedrooms listed, condition issues the assessment ignores). If you want to handle this yourself and keep 100% of any refund instead of paying a contingency firm's 30-40% cut, the TaxFightBack appeal kit walks through exactly how to gather and present that evidence.

You can read how the appeal process works county by county for major metro areas like Los Angeles County, Cook County, Maricopa County, and Bexar County.

How do you find your county's current mill rate?

Your tax bill is the first place to look. Most bills list each taxing authority and its rate as a line item. The sum is your total mill rate.

If your bill doesn't itemize it, your county assessor's or treasurer's website almost always publishes current and historical mill rates. Connecticut publishes all 169 towns' mill rates in a single table updated each fiscal year ^[2]. Georgia's Department of Revenue publishes a digest of millage rates by county ^[9]. Texas publishes each taxing unit's rate through the Texas Comptroller's office ^[8].

A few practical steps:

1. Search "[your county name] mill rate" or "[your county name] millage rate" plus the current year. 2. Look for the county auditor, treasurer, or assessor site rather than third-party aggregators, which sometimes lag by a year. 3. Confirm whether the rate is expressed in mills or as a percentage (e.g., "0.025" means 25 mills). 4. Note whether the published rate is the aggregate (all taxing bodies combined) or just the county's share.

For Georgia residents, the Gwinnett County tax assessor, Bibb County tax assessor, Cherokee County tax assessor, and Coweta County tax assessor offices all publish current millage rates on their sites, since Georgia's truth-in-taxation law requires public posting before adoption ^[9].

What is the difference between nominal mill rate and effective mill rate?

The nominal mill rate is the number your local government publishes. The effective mill rate is what you actually pay as a share of your home's real market value. They differ whenever assessed value doesn't equal market value.

Suppose your county's nominal mill rate is 50 mills but the county only assesses property at 50% of market value. Your effective mill rate is 50 x 0.50 = 25 mills relative to market value. A neighboring county with a nominal rate of 28 mills but a 100% assessment ratio actually taxes more.

That's why comparing nominal mill rates across counties or states is close to useless without knowing the assessment ratio. The Lincoln Institute's Significant Features database corrects for this by reporting effective rates, which is why their numbers look so different from what you'd calculate straight off published mill rates ^[5].

When you compare your situation to your neighbors for an appeal, the question is whether your assessed value is proportionally fair against other properties in the same jurisdiction, all of which face the same nominal mill rate. The effective rate on your specific parcel versus your neighbor's is the comparison that counts, and it comes down to assessed value per dollar of market value, not the mill rate.

How does the mill rate affect commercial property owners differently?

Commercial property owners often carry a higher effective tax burden through the class rate system rather than a different nominal mill rate. In Minnesota, commercial and industrial property has a class rate of 1.5% applied to assessed value before the mill rate calculation, while residential homestead property has a class rate of 1.0% on the first $500,000 of value ^[11]. That structural difference means commercial owners pay 50% more per dollar of assessed value even under an identical mill rate.

In states without class rates, local governments sometimes reach the same result by setting higher assessment ratios for commercial property. This has been challenged in courts in several states on equal protection grounds, with mixed results.

Commercial owners also tend to have a stronger hand in appeals because income-approach valuation (based on capitalized net operating income) often produces a lower value than cost or sales comparison approaches in a depressed commercial market. If your building's occupancy has fallen or rents have dropped, that income data is powerful appeal evidence that most county assessors won't have unless you hand it to them.

For major metro markets with significant commercial property, see our detailed breakdowns for San Diego, St. Louis County, Lake County, and Madison County.

What should you do if your mill rate seems wrong on your bill?

First, verify what the correct rate should be. Pull the official published mill rate from your county or city website for the tax year in question. Compare each line item on your bill to the published rates for each taxing body.

Bill errors aren't common, but they happen, especially in jurisdictions with many overlapping taxing districts. A miskeyed rate, a district boundary mistake, or a failure to drop a voter-approved levy that expired are all real possibilities.

If you find a discrepancy, call the county treasurer or tax collector's office first. Bring the bill and the published rate. Most genuine mill rate errors on bills get corrected administratively without a formal appeal.

If your concern isn't an error but simply that your total tax seems high, shift your focus to your assessed value. That's almost always the more productive fight. A 10% reduction in assessed value saves you 10% of your bill no matter what the mill rate is, and assessed value errors are far more common than mill rate errors.

TaxFightBack's appeal kit includes a bill audit worksheet that walks you through verifying both your assessed value and the mill rates applied, so you know before you file whether you're challenging the right number.

If you verify everything and still think you're treated unfairly next to your neighbors, look at comparable assessments. Your county's online property search usually lets you see other homes' assessed values. If similar houses nearby are assessed 15-20% lower than yours, that's your appeal case.

Frequently asked questions

What does 1 mill equal in property taxes?

One mill equals $1 of property tax per $1,000 of assessed value. On a home assessed at $200,000, one mill produces $200 in annual tax. On a home assessed at $400,000, one mill produces $400. That's why the mill rate matters more the higher your assessed value climbs.

How do I calculate my property tax using the mill rate?

Divide your assessed value by 1,000, then multiply by your total mill rate. Example: assessed value $275,000, mill rate 22 mills. ($275,000 / 1,000) x 22 = $6,050. If your state uses an assessment ratio below 100%, apply the ratio to market value first to get your taxable assessed value, then use that number.

What is a good mill rate for property taxes?

There's no universal 'good' rate. Context is everything. Hawaii counties run around 3-5 mills; parts of Illinois and New Jersey top 50 mills. What matters is your effective rate (tax as a percent of true market value). Nationally, the median effective rate was about 1.1% in 2023, per the Lincoln Institute of Land Policy. Rates above 2% generally indicate higher-tax jurisdictions.

Can I appeal my mill rate if I think it's too high?

No. The mill rate is set by elected governing bodies (city council, school board, county commission) through a public budget process. It is not subject to appeal through the assessor's office or board of equalization. Your recourse is political: attend public hearings on the budget, vote on millage referenda, or contact your elected officials. What you can appeal is your assessed value.

Why did my property taxes go up when the mill rate went down?

Because your assessed value rose faster than the mill rate dropped. If your assessed value increased 15% but the mill rate fell 5%, your bill still goes up about 10%. This is common in jurisdictions with truth-in-taxation laws that require a rollback rate: the mill rate is reduced just enough to keep total revenue flat, but individual owners whose values rose more than average still pay more.

How many mills is a 1% property tax rate?

A 1% property tax rate equals 10 mills. The conversion is straightforward: percentage x 10 = mills. So a 1.5% rate is 15 mills, a 2.0% rate is 20 mills. Some counties and states express tax rates as percentages rather than mills; they mean the same thing, just different notation.

Do different properties in the same county have different mill rates?

Not usually, but there are exceptions. Properties that fall in different municipal, school, or special district boundaries will have different total mill rates because different taxing bodies overlap different areas. Within the exact same set of taxing districts, all properties face the same mill rate. What varies by property is the assessed value, which is where your individual tax burden is really determined.

How does a homestead exemption reduce my tax if the mill rate stays the same?

A homestead exemption reduces your taxable assessed value, not the mill rate. If your assessed value is $300,000 and you have a $50,000 homestead exemption, the mill rate applies to $250,000 instead. At 20 mills, that saves you ($50,000 / 1,000) x 20 = $1,000 per year. The mill rate is unchanged; the base it's applied to is smaller.

What states have the highest mill rates?

Comparing nominal mill rates across states is misleading because assessment ratios differ. On an effective (market-value) basis, New Jersey, Illinois, Texas, and Connecticut consistently rank among the highest in the country, with effective rates above 1.8-2.5% according to Lincoln Institute data. Hawaii, Alabama, Colorado, and Utah consistently rank lowest, often below 0.5% effective.

Where can I find my county's current mill rate?

Start with your county assessor, auditor, or treasurer website and search for 'millage rate' or 'tax rate' plus the current year. Your tax bill itself usually lists each taxing body and its rate. State revenue departments often publish statewide tables: Georgia's Department of Revenue and Connecticut's Office of Policy and Management both publish annual mill rate tables for all their local jurisdictions.

What is the difference between a mill rate and a tax levy?

The levy is the total dollar amount a taxing body needs to collect. The mill rate is the ratio used to allocate that levy across property owners based on assessed value. Levy is the budget number; mill rate is the tool for dividing it. A higher levy means a higher mill rate if the total assessed base stays the same, and a lower mill rate if property values across the jurisdiction rise.

Does the mill rate change when I get a new assessment?

Your personal reassessment doesn't change the mill rate. Mill rates are set jurisdiction-wide based on the total assessed value of all properties and the government's budget needs. However, if a mass reassessment raises values across the whole jurisdiction, the governing body may lower the mill rate to avoid a windfall. Whether your individual bill goes up depends on whether your value rose more or less than the jurisdiction average.

Is the mill rate the same as the assessment rate?

No. The assessment rate (or assessment ratio) is the percentage of market value used to set taxable assessed value, for example 80% or 100%. The mill rate is the tax rate applied to that assessed value. They are two separate numbers that both affect your final bill. Some states combine them into a single effective rate for simplicity, but they are distinct concepts.

Can I use the mill rate to check if my neighbor is paying less than me unfairly?

Indirectly, yes. Since everyone in the same tax district faces the same mill rate, if your neighbor's assessed value per square foot is significantly lower than yours for a comparable home, you're paying more tax per dollar of actual home value. Pull your neighbor's assessment from the county property search, divide by home size, and compare to yours. A consistent gap across several similar homes is strong appeal evidence.

Sources

1. International Association of Assessing Officers (IAAO), Property Assessment Glossary: Definition of mill rate as the tax rate expressed in mills per dollar of assessed value and the formula for calculating it from levy and total assessed value.
2. Connecticut Office of Policy and Management, Mill Rates for FY 2023-2024: Connecticut publishes annual mill rates for all 169 towns reflecting all combined taxing body levies.
3. Michigan Department of Treasury, Headlee Amendment Overview: Michigan's Headlee Amendment requires voter approval for new or increased millages beyond the rate of inflation.
4. Lincoln Institute of Land Policy, Significant Features of the Property Tax, 2023: Assessment ratios vary by state and affect the relationship between nominal and effective mill rates; national median effective property tax rate was approximately 1.1% of market value in 2023.
5. Lincoln Institute of Land Policy, Significant Features of the Property Tax Database: Effective property tax rates by state ranging from approximately 0.28% in Hawaii to over 2.5% in parts of New Jersey and Illinois.
6. Urban Institute, State and Local Finance Initiative, Property Tax Data: Comparative effective mill rate data across major U.S. counties used in the comparison table.
7. Cook County Assessor's Office, Understanding Your Assessment: Cook County's complex assessment ratio system means nominal mill rates diverge substantially from effective rates paid relative to market value.
8. Texas Comptroller of Public Accounts, Property Tax Law Basics, Senate Bill 2 (86th Legislature): Texas SB 2 (2019) caps revenue increases above the rollback rate at 3.5% for most taxing units without voter approval.
9. Georgia Department of Revenue, Truth in Taxation Requirements (O.C.G.A. 48-5-32): Georgia requires local taxing authorities to publish and advertise millage rates before adoption under truth-in-taxation law; state publishes digest of millage rates by county.
10. Illinois Department of Revenue, Senior Citizens Assessment Freeze Homestead Exemption: Illinois senior freeze programs lock assessed value at a fixed base year amount, protecting against rising mill rate impact on long-term homeowners.
11. Minnesota Department of Revenue, Property Tax Class Rates: Minnesota applies a 1.5% class rate to commercial and industrial property versus 1.0% for residential homestead property before applying the mill rate, creating different effective burdens.