About the Property Tax Calculator
Property tax is quoted in units that look designed for comparison and are structured so that comparison does not work.
Three separate numbers sit between what a house is worth and the bill on it:
market value → assessed value → taxable value → tax
(assessment (exemptions) (mill rate)
ratio)Miss any one of them and the answer is wrong by a large factor rather than a small margin. This property tax calculator walks the whole chain and, more usefully, reports the one figure that can actually be compared between places.
How to Use the Property Tax Calculator
Enter the market value — what the property would sell for.
Enter the assessment ratio, the fraction of that value the assessor uses. It is often well below 100%.
Enter any exemption, such as a homestead exemption, and the mill rate your jurisdiction charges.
Step-by-Step Example
A $400,000 property, assessed at 40%, with a $25,000 exemption, at 25 mills.
Market value: 400,000
× 40% assessment ratio: 160,000
− 25,000 exemption: 135,000 taxable
× 25 mills (= 2.5%): 3,375$3,375 a year, or $281.25 a month.
Effective rate: 0.84% of what the property is actually worth — against a quoted rate of 25 mills.
Mills Are Not Percent
This is the commonest mistake in the subject, and it is out by a factor of ten.
One mill is one dollar per thousand dollars of assessed value. That makes it a tenth of a percentage point.
| Mills | As a percentage |
|---|---|
| 10 | 1% |
| 25 | 2.5% |
| 41 | 4.1% |
A 25 mill rate is 2.5%. Reading it as 25% turns a $10,000 bill into $100,000. The calculator shows what the mistaken figure would have been alongside the right one, because the gap is what makes the rule stick.
Why You Cannot Compare Two Towns by Their Mill Rates
Here is the trap, and almost everyone falls into it.
Town A: 25 mills on 40% of market value
Town B: 10 mills on 100% of market valueTown A's rate is two and a half times Town B's. The bills are identical.
On a $400,000 house both charge $4,000 — exactly 1% of what the property is worth. The assessment ratio absorbs the entire difference.
This means a headline mill rate, quoted on its own, compares nothing. A town can advertise a low rate while assessing at full value and cost more than a town with a rate twice as high assessing at a third. The only comparable number is the effective rate: tax as a share of market value, with the ratio and any exemptions already folded in.
The calculator reports it as a first-class output, and also restates your bill as the mill rate a full-assessment jurisdiction would need to charge — so you can compare like with like.
What an Exemption Is Actually Worth
Not its face value. An exemption reduces the value that gets taxed, so it is worth the rate times the exemption.
25,000 exemption × 2.5% = 625 a yearA $25,000 homestead exemption sounds substantial and saves $625. That is real money and worth claiming, but it is not $25,000, and budgeting as though it were is a meaningful error on a first home purchase.
Assessed Value Is Not an Opinion About Your House
A frequent worry: the assessment came in well below market value, so something must be wrong.
Usually nothing is. Most jurisdictions assess at a fixed statutory fraction of market value, applied to everyone. A 40% ratio means every property in the jurisdiction is assessed at 40%, and the mill rate is set high enough to raise the revenue needed against that smaller base.
What is worth checking is whether your assessed value is out of line with comparable properties nearby. That is the ground for an appeal. The ratio itself is not.
Understanding Your Result
Annual bill is the tax, with a monthly figure for escrow budgeting.
From value to taxable shows the whole chain, so you can see where each reduction happens.
What the mill rate means converts mills to a percentage and shows what misreading it would have cost.
Effective rate is tax as a share of market value — the comparable figure — plus the equivalent full-assessment mill rate.
Worth knowing flags the assessment ratio gap or the value of your exemption.
When Should You Use This Calculator?
Comparing neighbourhoods or towns. Use the effective rate, never the quoted mill rate.
Budgeting a purchase. Property tax is usually escrowed into the mortgage payment and is a permanent cost.
Checking a tax bill. If the arithmetic does not reconcile, the assessment or the exemption may be wrong.
Assessing an appeal. Work out what a lower assessed value would actually save before spending time on it.
Common Mistakes
Reading mills as percent. A 25 mill rate is 2.5%. The error is tenfold.
Comparing mill rates across jurisdictions. Meaningless without the assessment ratio.
Applying the mill rate to market value. It applies to assessed value, which is usually much lower.
Treating an exemption as a discount on the tax. It comes off the value, so it is worth the rate times the exemption.
Assuming a low assessment is an error in your favour. It is usually the statutory ratio applied to everyone.
Forgetting it recurs forever. Unlike stamp duty or closing costs, this is an annual cost that generally rises with reassessments.
Assessment ratios, mill rates, exemptions and reassessment cycles vary widely by jurisdiction, and special district levies may apply on top. Every figure here is an estimate for planning, not tax advice — check with your local assessor before relying on it.