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What is a mill rate?

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A mill rate is the number your town multiplies against your home's assessed value to set your tax bill. Here's where that number comes from, how to find yours, and why a "high" rate isn't always a high bill.

A mill is one one-thousandth of a dollar — from the Latin mille, "thousand." A mill rate (or "millage") of 18.5 means you owe $18.50 in property tax for every $1,000 of your home's assessed value. Connecticut's Office of Policy and Management states it plainly: a mill is "equal to $1.00 of tax for each $1,000 of assessment." That part is simple arithmetic. What confuses most homeowners is not the formula — it's where the rate comes from and why it changes.

If you just want the dollar figure, the mill rate calculator does the multiplication for you. This guide is about the part the calculator can't show you: how the rate is set, how to read it, and how to compare it honestly across places.

Your mill rate is built from a budget, not a market

Property tax is unusual among taxes: in most of the country the rate is a residual, not a fixed percentage set in advance. Local governments work backward from how much money they need to raise. The process, repeated every year by each taxing body, looks like this:

  1. The town, county, school board, and special districts each pass a budget.
  2. They subtract other revenue (state aid, fees, grants) to find the levy — the dollars that must come from property tax.
  3. The assessor totals the taxable value of every property in the district (the tax base).
  4. The rate is simply levy ÷ tax base, expressed in mills.

That is why your rate can rise even when no official "votes for a tax increase." If the budget grows faster than the tax base, the mill rate has to climb to cover the gap. It also explains the opposite: in a fast-appreciating market, rising home values can let a town hold the levy flat while the mill rate actually falls.

The rate on your bill is a stack

The single "tax rate" you see is rarely one government's number. It's the combined total of every overlapping authority with jurisdiction over your parcel. A typical Northeastern bill 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 and open-space: 1.1 mills
  • Combined: 28.6 mills

Each line is set by a different elected body on its own schedule, which is why two homes a few miles apart — same county, different school or fire district — can carry meaningfully different rates. When you research a neighborhood from the outside, it's easy to find the county rate and miss a special district that adds a mill or two on top.

Not everyone calls it a "mill"

The unit changes by region, but the math never does:

  • Mills (per $1,000) — common in the Northeast and Midwest.
  • Dollars per $100 — Texas and much of the South. Multiply by 10 to get mills (a "2.45 rate" = 24.5 mills).
  • Percent / "tax rate" — some Western states. Multiply by 10 to get mills (1.1% = 11 mills).

If your hand-calculation comes out 1,000× too high or too low, you've almost certainly mixed up the unit — for example, reading a millage of 0.0286 as if it were 28.6.

Why a high mill rate isn't always a high bill

A 28-mill town can be cheaper to live in than a 12-mill town. The reason is the assessment ratio — the fraction of market value your county actually taxes. A 28.6 mill rate applied to a home assessed at 70% of its market value is roughly the same burden as a 20 mill rate at 100% assessment. That's why comparing raw mill rates across states is misleading.

The honest cross-jurisdiction comparison is the effective rate: annual tax divided by market value. The US Census American Community Survey and the Tax Foundation's state tables both publish effective rates for exactly this reason. Our effective rate calculator converts your own bill into one.

Where to find your mill rate

  • Your tax bill — usually itemized by district; look for "millage," "tax rate," or "rate per $1,000."
  • Your county assessor or treasurer's website — most publish current rates by taxing district.
  • Your town's adopted budget — the levy and certified rate are set there before the bill is mailed.
  • Your Closing Disclosure — if you bought recently, the prorated tax line reflects the rate in effect.

Pull the current year's certified rate. Rates reset annually (twice a year in a few states), and the figure on the first search result is often several years stale.

Can you do anything about it?

Not the rate itself — it's set by elected officials and applies uniformly to every property in the district, so there's nothing to appeal. What you can challenge is the other half of the equation: your assessed value. Nearly all individual property-tax savings come from correcting an inflated assessment or claiming an exemption you qualify for, not from the rate.

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