How the property tax calculators work

The order of operations

1. Value. Start from the value the assessor sets (market value, full cash value, true and full value or appraised value, depending on the state).
2. Value-stage cap. Where a statewide cap limits growth in the value itself (Florida’s Save Our Homes, Texas’s homestead appraisal limit, Oklahoma’s fair cash value cap, and Arizona’s ordinary limited property value), the value is the lesser of this year’s value and last year’s capped value raised by the cap percentage. Oregon is different: maximum assessed value is the greater of 103% of prior assessed value and prior maximum assessed value; current assessed value is then the lesser of that result and current real market value. The cap is used only when you say you owned the home last year with no sale or new construction.
3. Assessment. Multiply by the statewide residential ratio (for example 10% in Alabama, 25% in Tennessee, 35% in Ohio), by the ratio for the class you choose, or by marginal class rates where the state taxes value in bands. Where the ratio is set by a county or town, you enter it.
4. Assessed-stage cap. Some caps apply to the assessed or taxable figure instead, such as Michigan’s taxable value and Alabama’s before-exemption assessment cap.
5. Exemptions. Statewide exemptions come off the value they are defined against, and only for the levy groups that honor them. Florida’s indexed second homestead band applies only to non-school levies; Texas school districts take a homestead exemption other units do not have to match. Each levy group therefore carries its own taxable value.
6. Levies. Each group’s taxable value is multiplied by the rate you enter in mills, dollars per $100 or percent. A rate fixed statewide (the District’s Class 1B rate, California’s 1% general levy, Alabama’s state levy) is built in.
7. Bill limits. Statewide limits on the bill itself, such as Indiana’s circuit-breaker caps and Oregon’s Measure 5 limits, cut the levies they cover.
8. Credits and charges. Statewide credits (Ohio’s rollbacks, Delaware’s senior school credit and others) come off the tax, then any local credit you enter; fixed charges and special assessments you enter are added last.

Unknown inputs stay unknown

A local rate is never filled with a state average, a cap is never applied without last year’s figure, and an age, disability or veteran exemption is never granted unless you say it has been approved. If a required input is blank, the calculator shows no total and says which input it needs. Optional local exemptions, credits and charges count as zero only when left blank in the optional section, and the result shows the amounts used.

Rounding

Assessed and taxable values and each levy line are rounded to the cent before they are added. Local offices may round some lines to whole dollars or apply rates with more decimals, so a bill can differ by a few cents per line. The monthly figure is the annual total divided by twelve; it is not an escrow quote.

Tax years and date limits

Each rule file states the tax year it describes and the last day its most time-limited figure applies. Successor year options are shown when their structure has been independently verified, such as the District’s next indexed deduction and Indiana’s pay-year deduction changes. An annual indexed figure is not carried into a later tax year without verification: once its last day passes, a worksheet uses the next year’s figure only after that figure has been read in the publishing agency’s own notice.

Census context

Each page shows the American Community Survey 2020–2024 medians for owner-occupied home value (table B25077) and real-estate taxes paid (table B25103), with their published margins of error. The two medians come from different distributions, so their quotient is labeled context: it is not the typical household’s effective rate and not a rate the calculator uses. The jurisdiction comparison contains 51 rows read from the official summary files.

Checking the results

Each jurisdiction’s rule file comes with worked examples whose arithmetic was done by hand from the cited statute or notice, and the engine must match every one to the cent. The main example is also entered into the worksheet on the state’s page, and the total it displays must equal the hand figure. How sources are chosen and how errors are corrected is set out in the editorial policy.

Sources for this page

• U.S. Census Bureau, ACS 2024 5-year table B25077 summary file
• U.S. Census Bureau, ACS 2024 5-year table B25103 summary file
• Statutes and agency notices for each rule: listed on each state page and collected on the sources page.