What it means
Property tax begins with two numbers: what the property is assessed to be worth, and the rate at which that value is taxed. The mill rate is the second number, quoted per thousand rather than as a percentage, a habit inherited from the Latin mille for thousand.
The arithmetic is simpler than the terminology suggests. Divide the mill rate by 1,000 to get the effective tax rate.
A mill rate of 25 is 2.5 percent, and a property assessed at 300,000 owes 7,500. The rate emerges from the local budget.
A town totals the revenue it needs from property tax, divides by the total assessed value in its jurisdiction, and the result, multiplied by 1,000, becomes the mill rate. When budgets rise faster than property values, the mill rate climbs; when values boom, the same revenue can be raised at a lower rate.
Several authorities often levy on the same property. A homeowner's bill may combine mill rates for the municipality, the school district and the county, and the total mill rate is what matters to the bill.
Assessed value adds its own complication. Many jurisdictions tax a property at a fraction of its market value, so the assessed figure on the bill may be well below the price the home would fetch, and comparing mill rates between places means comparing assessment practices too.
For business owners with premises, the mill rate is a real input into location decisions. Two nearby towns can differ noticeably in what the same building costs to hold each year, and official property tax guides from state authorities publish the actual rates.
In practice
Real-world examples.
Example
A town needs $12 million from property tax and its total assessed value is $600 million. The mill rate is $12,000,000 / $600,000,000 x 1,000 = 20, so a $250,000 property pays $5,000.
Example
A homeowner's bill shows three levies: municipality 11 mills, schools 18 mills, county 4 mills. The total of 33 mills on a $200,000 assessment produces a $6,600 annual bill.
Example
After a revaluation doubles local assessments, the town halves its mill rate and collects the same revenue. Homeowners with unchanged bills learn that mill rate and tax paid are different things, while owners whose homes rose faster than average see their bills climb.
Formula
Calculation
Property tax = assessed value x mill rate / 1,000. Reversing it, mill rate = required revenue / total assessed value x 1,000.
Worked example. A property assessed at $400,000 in a district with a total mill rate of 27.5 owes $400,000 x 27.5 / 1,000 = $11,000 a year. If the town raises its rate by 2 mills to 29.5 and the assessment is unchanged, the bill becomes $400,000 x 29.5 / 1,000 = $11,800, an increase of $800. The same 2-mill rise on a $250,000 property adds only $500, which shows why the assessment matters as much as the rate.Case study
Seen in the real world.
Fictional example: Tindall Manufacturing, an imagined components maker, shortlisted two towns for a new plant. Town A advertised a mill rate of 18, Town B one of 24, and the choice looked obvious until the finance team read the assessment rules. Town A assessed industrial property at full market value; Town B assessed at 60%. In effective terms, Town B's rate per dollar of market value was 24 x 60% = 14.4 mills, well below Town A's 18, so on a $5 million plant the annual bill would be about $72,000 in Town B against $90,000 in Town A.
Other factors, such as labour supply and freight costs, still mattered, but the comparison reversed the headline. The site report to the board carried a lesson in bold: never compare mill rates without converting both to tax per dollar of the market value you will actually pay to buy or build. The company and figures are invented.
Watch out
Common mistakes.
- Treating the mill rate as a percentage, when one mill is one-tenth of a percent and the rate must be divided by 1,000 before use.
- Comparing mill rates between jurisdictions without checking how each assesses value, since the assessment ratio changes the effective tax.
- Watching only the mill rate at revaluation time, when the bill depends on the rate multiplied by the new assessed value.
Questions
People also ask.
What does one mill mean in money?
One mill is one-tenth of a cent, or $1 of tax per $1,000 of assessed value. A mill rate of 20 therefore means $20 per $1,000, an effective rate of 2%.
Who sets the mill rate?
The local taxing authorities, such as municipalities, school districts and counties. Each divides the revenue it needs by the total assessed value in its area, and the rates are added together on the owner's bill.
Why did my bill rise when the mill rate fell?
Because assessed value rose faster. The tax is the rate times the assessment, so a revaluation that lifts values more than the rate falls still produces a larger bill.
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