What Is a Millage (Mill) Rate? How to Calculate Your Property Tax

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A millage rate, or mill rate, is the property tax rate expressed in mills, where one mill equals one-thousandth of a dollar. In property tax terms, 1 mill means $1 of tax for every $1,000 of a property’s taxable (assessed) value. A millage rate of 20 therefore means $20 owed per $1,000 of assessed value, which is the same as 2% of that value.

What Is a Millage (Mill) Rate?

The word comes from the Latin millesimum, “thousandth.” The U.S. Coinage Act of 1792 defined the mill as one-tenth of a cent, or 1/1,000 of a dollar. It has always been a unit of account rather than a regular coin, which is why it survives mainly in tax rates and, informally, in fuel prices that end in 9/10 of a cent.

Property taxes are ad valorem taxes, meaning they are levied in proportion to value. Expressing the rate in mills keeps the numbers readable. A rate of 0.0185 written as a decimal becomes 18.5 mills, or $18.50 per $1,000.

The spelling is “mill.” “Mil” is a different unit, a thousandth of an inch, though it appears informally in tax discussions.

How a Millage Works

How Rates Are Set

Each taxing authority that covers your property sets its own millage. That can include the county, the city or township, the school district, and districts for fire, library, water or hospital services. The process generally runs backward from the budget:

1. The authority adopts a budget for the year.
2. It subtracts revenue it expects from other sources (state aid, fees, sales tax shares).
3. The remainder is the levy, the amount property taxes must raise.
4. The levy is divided by the total taxable value in the jurisdiction and multiplied by 1,000.

Hypothetical example: a school district needs a levy of $12 million and the taxable value in its boundaries is $800 million. $12,000,000 ÷ $800,000,000 × 1,000 = 15 mills.

The rates from every overlapping authority are added to give the total millage on your bill. Some states let rates differ by property class, so residential, commercial and industrial property may face different millages or different assessment treatment.

Calculating Millage

The core formula:

Property tax = (Taxable value × Millage rate) ÷ 1,000

With a 7-mill rate and a $150,000 taxable value: 150,000 × 7 ÷ 1,000 = $1,050. A quick shortcut is to divide the taxable value by 1,000 (150,000 / 1,000 = 150) and multiply by the mills (150 × 7 = 1,050).

Useful conversions:

Some jurisdictions quote rates per $100 of value instead of in mills. Multiply a per-$100 rate by 10 to get mills. To estimate a monthly amount, such as an escrow payment, calculate the annual tax and divide by 12.

Interpreting a Millage

The millage rate tells you the price per $1,000 of taxable value, not of market value. The taxable value usually passes through three steps:

• Market value: the assessor’s estimate of what the property would sell for, based on local sales data. Assessments are commonly updated on a regular cycle, often annually.
• Assessed value: in many places, market value multiplied by an assessment ratio set by law (for example, a hypothetical 40%).
• Taxable value: assessed value minus exemptions, such as a homestead exemption for an owner-occupied primary residence. With a $50,000 homestead exemption, a home with a $200,000 assessed value is taxed on $150,000.

Example of a Millage

All figures below are hypothetical.

• Market value: $300,000
• Assessment ratio: 40%, so assessed value = $120,000
• Homestead exemption: $25,000, so taxable value = $95,000

Millage rates on the bill:

Tax = 95,000 × 34 ÷ 1,000 = $3,230 per year, about $269.17 a month if paid through escrow.

Note the gap between the stated rate and the burden on market value. 34 mills is 3.4% of taxable value, but $3,230 is only about 1.08% of the $300,000 market value. That second figure is the effective tax rate: annual tax ÷ market value.

Why Is a Millage Important?

Property tax is a major revenue source for local government, funding schools, roads, emergency services and parks. Every state levies property taxes, even though some levy no income tax. Knowing your millage lets you:

• Estimate the tax on a home before buying it.
• Check your bill line by line and see which authority charges what.
• Judge a proposed rate increase. A ballot measure adding 2 mills costs $2 per $1,000 of taxable value; on the $95,000 example above, that is $190 a year.
• Spot an assessment problem. If the rate is right but the bill looks high, the assessed value is the likely issue. Owners who believe their property is over-assessed can generally appeal or request a reassessment through the local assessor or review board.

What a Millage Rate Change Means

A change in millage changes the price per $1,000, but your bill depends on both rate and value. A lower rate does not guarantee a lower bill.

Hypothetical: the example property’s taxable value rises 10% to $104,500, and the total rate is cut from 34 to 32 mills. The new tax is 104,500 × 32 ÷ 1,000 = $3,344, which is $114 more than before.

For this reason, some states require taxing authorities to calculate a “rollback” or similarly named rate: the millage that would raise the same revenue as the prior year on the reassessed base. Florida’s Truth in Millage (TRIM) law, for example, requires a notice comparing proposed taxes with those under the rolled-back rate. Rules and terminology vary by state.

Limitations of a Millage

• It does not compare places on its own. Two towns with identical millage can produce very different bills if one assesses at 100% of market value and the other at 35%. Compare effective tax rates or actual bills on similar homes instead.
• Exemptions and credits sit outside the rate. Homestead, senior, veteran or disability exemptions, and caps on annual assessment increases, can change your tax without any change in millage.
• Total millage can obscure its parts. A single number may combine voted levies, debt service for bonds and operating rates, each with different rules for how they can change.
• It applies to property only. A “mill” rate has nothing to do with sales tax on purchases, which is a percentage of the price. Consumption taxes such as VAT or GST work on transactions, not ownership.

FAQs

The Bottom Line

Homeowners, buyers and anyone weighing a local tax measure can use the millage rate to estimate a bill: multiply taxable value by the total mills and divide by 1,000. The rate alone says little, though, because assessment ratios, exemptions and rising values shape the final amount, and a lower rate can still produce a higher bill. To compare places or check a bill, look at effective tax rates and the assessed value, and appeal an assessment that looks too high.