What your RVC tax bill is actually made of

Three taxes, two rolls, three value concepts

School + library + county/town taxes are computed on the Nassau County roll: your taxable assessed value (AV) × rate per $100. Class-1 AV = 0.1% of the county's "effective market value" (EMV) for that roll year — and the EMV lags the county's own Fair Market Value estimate because class-1 AV can't rise more than 6%/yr or 20%/5yr (RPTL §1805, the Taxpayer Protection Plan phase-in). The roll has been carried forward since the 2020-21 reassessment, so bill-era EMVs sit years behind the market.

The village tax is computed on the Village of Rockville Centre's own roll — its own assessed values (total $59.7M FY26 / $59.4M FY27) at its own level of assessment (NYS equalization rate: 0.87% for 2025), times the village rate ($69.89 FY26 → $74.91 FY27 per $100 of village AV).

Your sense of market value (Zillow, a recent appraisal) is a third number, usually higher than both roll values. Dividing a real bill by a flat "effective rate" and calling the result "your home's value" mixes all three bases — that's the math behind most $900K-vs-$1.1M confusions, including the one that prompted this page.