Successful tax assessment reductions in Nassau reach 11-year high, data shows

Nassau County settled a higher number of cases with homeowners disputing their property assessments this year compared with the previous year, reducing assessments for nearly 184,000 residents — more than the county has in the last 11 years, according to data obtained by Newsday.

About 81% of those who filed a grievance were successful in reducing their assessments, according to the data obtained through a public records request. This marks the second consecutive year in which successful tax assessment reductions rose. About 79% of homeowners successfully grieved their tax assessment the year prior. 

Nassau’s settlement rate with taxpayers has steadily increased following a countywide reassessment of hundreds of thousands of properties under former Nassau County Executive Laura Curran. She updated tax rolls that had been frozen for nearly a decade before. Since then, officials have frozen tax rolls once again, increased settlements and shifted the tax burden onto a shrinking group of Nassau residents.

Homeowners unhappy with how the county assesses the value of their home — multiplying its estimated market value by a "level of assessment" of 0.1% — can file a grievance with Nassau’s Assessment Review Commission, which looks at nearby home sales and uses a lower rate of 0.066% to get its assessed values. About 60% of Nassau homeowners filed a formal appeal of their property assessment for the 2025-26 tax year. The county lowered assessments for 48% of total Nassau homeowners, or nearly 183,700 people, lowering their property values by an average of 7%.

Home prices in Nassau are soaring at a rate higher than almost any other county in the nation, jumping 12% since last year. Researchers who specialize in property taxes say that relying on frozen tax rolls as homes gain value in the market leaves taxpayers who want an accurate assessment of their home no choice but to file a grievance.

"There needs to be regular reassessments done. ... That allows for any changes in the market to be captured," Mark Sunderman, a professor at The University of Memphis in Tennessee and real estate expert, previously told Newsday.

The county is settling more grievance cases with homeowners in part because the ARC has lowered its assessment rate over time. This year’s rate was 0.066%, last year’s was 0.072% and the year prior was 0.08%. With homes being assessed by the ARC at a lower rate, more homeowners who file a grievance automatically get a settlement.