Assessments in Nassau County are established by the County Assessor. The tentative assessment for each year is set in January of the prior year (i.e., in January 2025, the 2026 tentative assessment is set). That tentative assessment is not finalized until the following April. For example, in January 2025, the 2026 tentative assessment is set but is not finalized until April 2026 for the 2026-2027 school tax year and the 2027 general tax year.

In Nassau County, the tax grievance process commences with the filing of a grievance with the Assessment Review Commission (“ARC”). If the matter is not resolved at ARC, an appeal for residential properties can be filed in small claims court, which is called a Small Claims Assessment Review (“SCAR”) proceeding, and an appeal for commercial properties can be filed in the Supreme Court which is called a tax certiorari proceeding. As stated above, in Nassau County, the property owner is challenging the tentative assessment set in January which doesn’t become final until the following year. So in January - March 2025, you are challenging the assessment for the 2026-27 school tax year and the 2027 general tax year.

The deadline to file a grievance in Nassau County is March 3, 2025. Click here to apply

When Cobra timely files your grievance by March, ARC will typically advise Cobra of the result and/or seek a conference to discuss a settlement before the end of the year, but no later than March of the following year. Cobra keeps you appraised throughout the process. If a reduction is obtained, the reduction is reflected in the final tax roll set for the following year. As such, a reduced assessment for the 2025 grievance will be reflected on the 2026-2027 tax roll and tax bills.

Typically, a tax refund will not be issued because your assessment is reduced before the tax roll is finalized. On the other hand, if the ARC decision is appealed through a SCAR proceeding, and that decision is not made before the roll is finalized, a refund could be owed to the property owner. In recent years, ARC has made most decisions prior to the tax role being finalized.