Property Tax Calculator

Tax = (market value × assessment ratio − exemptions) × rate, where a mill rate is divided by 1,000 (1 mill = $1 per $1,000). Over time, the assessed value grows with the market but a reassessment cap, where one exists, limits how fast the taxable value can rise.

Mill rates, percentages and the assessment ratio

Property tax is a rate applied to a base, but two local quirks complicate the simple picture. First, the rate may be quoted as a percentage or as a mill rate — a mill is one dollar of tax per thousand dollars of value, so 11 mills is the same as 1.1%. This calculator takes either; just flip the toggle. Second, the tax is charged not on the market value but on the assessed value, which in many jurisdictions is a fraction of market value set by an assessment ratio. Enter that ratio and the calculator works on the assessed base, then reports the effective rate against market value so you can compare like with like.

From there it is straightforward: assessed value, minus any exemptions, times the rate, plus any flat special assessments, gives the annual tax — and dividing by twelve gives the monthly figure that goes into a mortgage escrow account. That monthly number is the “T” in the PITI payment the mortgage calculators compute.

Worked example — a $400,000 home taxed at 1.1% (or 11 mills): With no assessment discount, the taxable value is $400,000 and the tax is $4,400 a year — about $367 a month for escrow. Apply an 80% assessment ratio and a $25,000 homestead exemption and the taxable value drops to $295,000, cutting the tax to $3,245.

Exemptions and special assessments

Most US homeowners qualify for at least one exemption that reduces the taxable base. A homestead exemption knocks a fixed amount (or sometimes a percentage) off the assessed value of a primary residence; seniors, veterans and people with disabilities often get additional ones. Enter the total as a flat amount or a percentage and the calculator subtracts it before applying the rate, showing both the reduced taxable value and the tax it saves. These exemptions are easy to overlook and can be worth hundreds a year.

Pulling the other way are special assessments — flat levies for schools, sewer districts, street lighting or local bonds that sit on top of the general rate. They are not a percentage of value, so they hit smaller properties proportionally harder. Add them as an annual amount and they are included in the total and the monthly escrow figure.

Projecting forward — and why caps matter

Property values rise, and so, usually, does the tax — but not always in lockstep, because several states cap how fast the taxable value can grow. California’s Proposition 13 is the famous example, limiting annual increases to 2% until the property changes hands. Set a projection horizon and an annual growth rate and the calculator projects the tax year by year; add a reassessment cap and it holds the taxable value’s growth to that limit, which can keep a long-time owner’s tax far below what the market would imply.

The projection matters for budgeting a home you will hold for years, and for understanding why two neighbours in identical houses can pay very different taxes. The table breaks out the assessed value, exemptions and tax for each year, and the chart traces the tax over time — gently sloping where a cap applies, steeper where it does not.