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Assessed × millEffective rateFree

Property Tax
Calculator

Estimate annual property tax for feasibility and pro-formas. Enter the market value, the assessment ratio your jurisdiction applies, and the mill rate (or tax percentage).

Who it's for: architects, developers, and project owners estimating annual tax liability for pro-formas and site feasibility studies.

Tax = assessed value × mill ÷ 1,000
Assessed value = market value × assessment ratio. Tax = assessed value × (mill rate / 1,000), or assessed × tax%. A "mill" is $1 per $1,000 of assessed value. Ratios, exemptions, and special assessments vary widely by jurisdiction.
Property Tax
Annual estimate

How to use this calculator

1
Enter the market value
The property's estimated or appraised market value in dollars. Use the purchase price, a recent appraisal, or your feasibility assumption.
2
Enter the assessment ratio
The percentage of market value your jurisdiction treats as the taxable base. Obtain the ratio for the property class and tax year from the official assessor or revenue authority.
3
Choose how the rate is given
Select mill rate if you have dollars per $1,000 of assessed value; select tax rate percentage if that is how your jurisdiction publishes it.
4
Enter the rate
Type the current mill rate or tax percentage published by the official taxing authority. Confirm whether the published figure is a combined rate or whether separate levies must be added first.
5
Read the annual tax
The result shows the estimated annual tax bill, the assessed value used, and the effective rate as a percentage of full market value.

The formula

The calculator first applies the user-supplied assessment ratio, then applies the user-supplied jurisdictional rate. Assessed value = market value × assessment ratio ÷ 100.
Tax using mills = assessed value × mill rate ÷ 1,000.
Tax using percent = assessed value × tax rate ÷ 100.
Market value is the value entered for the property.
Assessment ratio is the percentage applicable to the property's classification and tax year.
Mill rate is dollars of tax per $1,000 of assessed value. The calculator does not select or verify either jurisdictional input.

Worked example

Example
A property with a $500,000 market value, an 80% assessment ratio, and a 25-mill rate has an assessed value of $400,000. Tax = $400,000 × 25 ÷ 1,000 = $10,000/year. The effective rate on full market value is 2.000%.

When this estimate will be off

  • Assumes the entered rate represents every applicable levy. If the property is subject to separate county, municipal, school, or special-district rates, combine them only as directed by the responsible taxing authorities.
  • Exemptions and deductions (homestead, senior, veteran, agricultural) are not modeled; they can significantly reduce the assessed value or the final tax bill.
  • Assessment ratios and mill rates can change by tax year; use figures published for the property's jurisdiction, classification, and applicable year rather than a historical or neighboring rate.
  • Special assessments, tax-increment districts, and abatement programs are not modeled and can change the amount due from the base calculation.

Frequently asked questions

A common mistake: Assumes the entered rate represents every applicable levy. If the property is subject to separate county, municipal, school, or special-district rates, combine them only as directed by the responsible taxing authorities.

A mill rate is tax per $1,000 of assessed property value. A rate of 25 mills means $25 for every $1,000 of assessed value, or $10,000 on a $400,000 assessed value. Verify the applicable rate and whether it includes every taxing district with the official assessor, treasurer, or revenue authority.

The assessment ratio is the percentage of market value used to calculate assessed value. An 80% user-entered ratio on a $500,000 property produces a $400,000 assessed value. The correct ratio can depend on jurisdiction, property classification, and tax year. Obtain it from the official assessor or revenue authority.

Local bills layer multiple jurisdictions — county, city, school district, and special districts — each with its own rate, and subtract applicable exemptions. Enter the total combined millage and confirm any exemptions with the local assessor for a closer estimate.

Use the result as a feasibility estimate, not as a tax determination. For underwriting, confirm the valuation basis, assessment ratio, total applicable rate, exemptions, caps, abatements, and special assessments with the responsible government authority. The seller's current bill may not represent tax after a sale, reassessment, or change in use.

Sources

  • Calculation basis — Arithmetic applied to the market value, assessment ratio, and mill or percentage rate entered by the user; no default jurisdictional rate is supplied.
  • Required local authority — Verify the property class, assessment ratio, tax year, combined levies, exemptions, and special assessments with the official assessor, treasurer, or revenue authority for the property.

This free Property Tax Calculator is built and maintained by DataDrivenAEC, using the relevant codes and standards. It does not substitute for professional judgment.