What Is Millage Rate?

Start with the arithmetic, because it is the whole story. A "mill" is one-tenth of a cent, so 1 mill is $1 for every $1,000 of taxable value. Taxable value is your assessed value after exemptions. A home with $300,000 of taxable value at 20 mills owes $300,000 / 1,000 x 20 = $6,000 a year, and every added mill costs that home another $300.

The rate you pay is a stack, not a single number. Your county commission, city, school board, and special districts (fire, library, water management, community college) each adopt their own millage, and the tax collector adds them together on one bill. That is why a county can announce it is "holding the line" on its rate while your bill still rises: another authority in the stack raised theirs, or the assessed value the whole stack multiplies went up.

What a mill is worth depends on how your state assesses, and in Florida it also depends on which levy you are looking at. Florida applies mills to 100% of assessed value, but the homestead exemption reduces that base differently by levy: the first $25,000 is exempt from every levy, including school district millage, while a second tier, indexed to inflation since 2025 and worth $26,411 for 2026, covers only the assessed-value band between $50,000 and $76,411 and is exempt from non-school levies only. That means a homesteaded property's taxable value for school taxes runs up to $26,411 higher than its taxable value for county, city, and special-district taxes. Georgia assesses homes at 40% of fair market value, so a $350,000 home carries $140,000 of assessed value and one mill is only $140 (30 mills produces $4,200, 31 mills $4,340). Mississippi assesses owner-occupied homes at 10% of true value, so on a $350,000 home one mill is $35 and a 2-mill increase costs $70 a year before the homestead credit. Alabama also uses a 10% assessment class for owner-occupied homes: the Department of Revenue's own example is a $100,000 home at 32.5 mills paying $325. Comparing millage rates across states, or even across levy types within the same Florida bill, without accounting for the base each rate applies to tells you nothing.

Rates change through the budget, and most millage states force a rate increase into the open. Florida requires every taxing authority to publish its rolled-back rate, the millage that would raise the same revenue as last year, on the August TRIM notice, hold two public hearings, and advertise any rate above the rolled-back rate as a "Notice of Proposed Tax Increase." Georgia's Taxpayer Bill of Rights works the same way with a roll-back rate, a published "Notice of Property Tax Increase," and three public hearings, one of them in the evening. In both states a county that leaves its rate unchanged after a reassessment still has to advertise a tax increase, because the same mills on a bigger tax digest collect more money. Mississippi counties levy in September (no later than September 15) and must run a quarter-page "Notice of a Tax Increase" advertisement for two consecutive weeks first, let any citizen speak before the vote, and keep total receipts within 10% of any of the prior three years. South Carolina caps a local government's operating millage increase at inflation plus population growth (a 2.63% inflation component for fiscal 2026-27). Pennsylvania's caps are uneven by level of government: school districts generally may raise taxes only up to the state's Act 1 index, 3.5% for 2026-27, without voter approval, though a district can exceed the index without a referendum if the state approves an exception for debt service, special education cost growth, or rising pension costs. Counties and most municipalities are not governed by Act 1 at all; they answer to their own statutory millage caps instead, 25 mills for general county purposes under the County Code (absent a court petition to exceed it) and 30 mills for boroughs and first class townships, while narrower levies like debt service sit outside those caps. Ohio splits millage into unvoted "inside" mills and voter-approved "outside" mills, and HB 335 (effective March 2026) now limits how much revenue inside millage can gain from a reappraisal.

Michigan runs the general rule in reverse, and the mechanism is more specific than a simple growth threshold. Its Headlee Amendment requires each local unit to calculate a Millage Reduction Fraction every year: prior-year taxable value, minus losses like demolitions, times the state's inflation rate multiplier, divided by current-year taxable value, minus new construction and other additions, capped at 1.0000. Because new construction is stripped out of the current-year side before the comparison, a district can add substantial new development without that growth alone forcing a rollback; the fraction responds only to appreciation of the existing tax base. The State Tax Commission set the 2026 inflation rate multiplier at 1.027 in Bulletin 14 of 2025, for use in both the Proposal A capped-value formula and the Headlee Millage Reduction Fraction; each local unit then works out its rollback under MCL 211.34d and the procedures in State Tax Commission Bulletin 2 of 2026. A Headlee rollback can be restored by a voter-approved override election. Proposal A is the separate, better-known cap that limits how fast an individual home's own taxable value can grow (the lesser of 5% or inflation) until it sells; the two run at the same time but measure different things. Michigan also levies a 6-mill State Education Tax on top of local rates.

What you can do about a millage increase is narrower than what you can do about an assessment. No appeal board has jurisdiction over the rate; it is set by elected officials, and your remedy is the public hearing printed on the notice, or the ballot when a levy needs voter approval or a Headlee override. What you can appeal is the taxable value the mills multiply, and lowering it is real leverage regardless of which way the rate moves: in Florida, for example, a successful challenge to your home's just value can lower assessed value dollar-for-dollar in the same year, though the Save Our Homes 3% cap means assessed value is already the lesser of just value or the capped prior-year value, so how much room exists between the two determines the size of the win. Florida gives you 25 days from the TRIM mailing to petition the Value Adjustment Board, Georgia gives you 45 days from the assessment notice, and Mississippi takes written objections at the Board of Supervisors' equalization meeting on the first Monday in August. Exemptions shrink the base the same way: Florida's homestead exemption removes up to $51,411 of taxable value for 2026, split as described above between school and non-school levies, and Mississippi's homestead credit is worth up to $300, with owners 65 or older or disabled exempt on the first $7,500 of assessed value.