Mill rate → annual tax

Understanding mill rates

A mill is one one-thousandth of a dollar — Latin mille, "thousand." If your local mill rate is 18.5, you pay $18.50 in property tax for every $1,000 of your home's assessed value. The arithmetic is simple; the complications come from what feeds into each side of the equation.

Annual tax = Assessed value × (Mill rate ÷ 1,000)

The mill rate you see on a typical tax bill is rarely a single number. It's the stacked total of every taxing authority with jurisdiction over your parcel. A single bill in a Connecticut town might add up like this:

• Town general government: 7.4 mills
• Public schools: 14.1 mills
• County: 4.8 mills
• Fire district: 1.2 mills
• Library district: 0.4 mills
• Open-space bond: 0.7 mills
• Combined: 28.6 mills

That stack is the number you plug into the calculator. Every line is set by a different elected body on a different schedule — which is why mill rates can drift year over year even when your local "headline" rate is held flat.

Assessed value is not market value. Most counties assess at a fraction of market value (often called the assessment ratio). A home that would sell for $500,000 may have an assessed value of $425,000 — or $350,000, or $400,000 — depending on local rules. Look at your most recent assessment notice or the property record card on your county assessor's website to find the assessed value your taxing authorities are actually using.

Mill rate vs. effective rate

Mill rate is the lever local governments pull. Effective rate is what you actually pay, expressed as a percentage of your home's market value. The two diverge whenever the assessment ratio isn't 100%, when exemptions are applied, or when caps (Florida's Save Our Homes, California's Prop 13) suppress the assessed value below market.

A 28.6 mill rate sounds frighteningly high until you realize that an assessment ratio of 70% drops the effective rate from 2.86% to about 2.00%. A 9.2 mill rate at 100% assessment is roughly the same effective burden as a 13 mill rate at 70% assessment. When comparing across counties or states, work in effective rate or you will compare apples to oranges.

Where to find your mill rate

• Your most recent property tax bill — usually broken out by line item; sometimes labeled "tax rate," "millage," or "rate per $1,000"
• Your county assessor or treasurer's website — most publish current mill rates by taxing district
• Your municipality's annual budget document — the rate is set there before being certified to the county
• Your closing statement (HUD-1 / Closing Disclosure) — if you bought recently, the prorated tax line shows the rate in effect

Worked examples

Example 1 — Connecticut suburb. A home with an assessed value of $350,000 in a town with a 28.6 mill rate:

• $350,000 × (28.6 ÷ 1,000) = $10,010 annual property tax
• ≈ $834 per month through mortgage escrow
• If the home's market value is $500,000, the effective rate is 2.00%

Example 2 — Florida coastal county. The same homeowner moves to a Florida county where the combined millage is 9.2 and the home is appraised at $500,000 just-value (Florida assesses at 100% of just value):

• $500,000 × (9.2 ÷ 1,000) = $4,600 annual property tax
• After a $50,000 homestead exemption: $450,000 × (9.2 ÷ 1,000) = $4,140
• Effective rate: 0.83%

Example 3 — Texas suburb. Texas tax bills typically express the rate as dollars per $100 rather than mills. A combined rate of 2.45 per $100 equals 24.5 mills. On a $400,000 home assessed at 100% market value:

• $400,000 × (24.5 ÷ 1,000) = $9,800 annual property tax
• The same math, just expressed in different units — multiply Texas's "per $100" rate by 10 to get mills

Common mistakes

• Using market value instead of assessed value. If your county assesses at less than 100% of market value, plugging in your Zillow estimate will overstate your tax bill, sometimes by 20–30%. Always use the assessed value from your county records.
• Forgetting special assessment districts. Community development districts (CDDs) in Florida, Mello-Roos in California, and municipal utility districts (MUDs) in Texas can add 0.5–2.0 mills (or more) on top of the headline rate. They show as separate line items on the bill but are easy to miss when researching a neighborhood from outside.
• Using last year's rate. Mill rates reset annually. Some jurisdictions reset twice a year (winter/summer in Michigan, for example). Pull the current year's certified rate, not whatever Google's first result shows from three years ago.
• Ignoring exemptions. The taxable value the rate is applied to is your assessed value minus any exemptions (homestead, senior, veteran, disability). A $50,000 homestead exemption on a 28.6 mill rate saves $1,430 a year — every year — until the property changes hands.
• Confusing "mill" with "millage rate." Some states list a "millage rate" of 0.0286 instead of 28.6. Same number, different decimal placement. If your math comes out 1,000× too low, you've used the wrong form.

Frequently asked questions

What is a "good" mill rate?

It depends entirely on the assessment ratio and what services it funds. A 28 mill rate in a Connecticut town with strong public schools and 70% assessment can be the same effective burden as a 12 mill rate in a state with 100% assessment and lower school funding. Compare effective rates (annual tax ÷ market value), not raw mill rates, when shopping across regions.

How often do mill rates change?

Almost always annually. Local taxing bodies — town councils, county commissions, school boards — pass a budget, calculate the rate needed to fund it, and certify the rate before the bill is mailed. Big changes (more than a mill or two) usually accompany a referendum, a state-imposed cap reset, or a reassessment cycle.

Can I negotiate or appeal my mill rate?

No. The mill rate is set by elected officials and applies uniformly to every property in the taxing district. What you can appeal is your assessed value — and that is where almost all individual property tax savings come from. See our assessment appeal calculator to project the savings.

Why does my neighbor pay less than I do on a similar house?

Five common reasons: (1) different exemptions claimed (homestead, senior, veteran), (2) older assessment that didn't catch a recent market move, (3) different special-district overlay, (4) a successful prior appeal, or (5) an abatement from an economic-development incentive. The first two are the usual culprits.

Does the mill rate apply to the whole assessed value?

It applies to the taxable value, which equals assessed value minus exemptions. If your home is assessed at $350,000 and you have a $25,000 homestead exemption, the rate is applied to $325,000.

What's the difference between a mill rate and an effective rate?

Mill rate is the rate set by your taxing authorities, applied to assessed value. Effective rate is what you actually paid divided by your home's market value. Effective rate is the better cross-jurisdictional comparison because it folds in the assessment ratio and exemptions. Use our effective rate calculator to convert.

Are mill rates the same as property tax rates everywhere?

Not quite. Mills (per $1,000) are common in the Northeast and Midwest. Texas and other Southern states often use "rate per $100" — multiply by 10 to get mills. Some Western states publish an "effective rate" or "tax rate as a percentage" — multiply by 10 to get mills. The underlying math is identical; only the units differ.

Why did my bill go up if the mill rate didn't?

Because the other half of the equation moved. Reassessment captures market appreciation, exemption phase-outs (Florida's Save Our Homes resets when you sell) lift the taxable value, new improvements add taxable basis, or a new special-assessment district was overlaid on your parcel. See our reassessment impact calculator to quantify a value change.