THE NUMORIX GUIDE
How to use the Property Tax Calculator
Last reviewed September 14, 2026
What this calculator does
The calculator applies either taxableValue x rate / 100 for percent mode or taxableValue x rate / 1,000 for mills mode.
Formula and method
The calculator applies either taxableValue x rate / 100 for percent mode or taxableValue x rate / 1,000 for mills mode. Special assessment is added separately to annual tax to produce totalAnnual; monthlyTax is only the ad valorem annual tax divided by 12 and does not include the special assessment.
Variables and inputs
Enter taxable assessed value, rate, rate mode of percent or mills, and special assessments per year. Values are dollars except the rate; a mill is one dollar per $1,000 of taxable value.
Worked example
For taxable value $280,000 and a 1.2% effective rate, annual ad valorem tax is 280,000 x 1.2 / 100 = $3,360 and monthly equivalent is 3,360 / 12 = $280. With a $600 special assessment, total annual estimate is 3,360 + 600 = $3,960; the route still displays $280 as monthlyTax because the assessment is shown separately.
How to interpret the result
The result estimates the tax from the taxable value and one rate. Taxable assessed value may differ from market or purchase price, and special assessments can be billed separately. The official bill and local assessment rules control the actual obligation.
Common mistakes to avoid
Use 1.2 in percent mode for 1.2%, or 12 in mills mode for 12 mills. Do not enter a market value when the authority uses a different assessed or taxable value. Remember that monthlyTax does not include the special assessment in this engine.
Assumptions and limitations
The calculator does not infer exemptions, assessment caps, reassessment timing, local levies, homestead rules, delinquency, or installment billing. Percent and millage conventions vary by jurisdiction, so the entered rate must come from the relevant tax authority.