Nassau County 2027–28 tentative assessment roll

Nassau County’s Department of Assessment publishes a new tentative assessment roll every January. The roll lists every parcel in the county and assigns each a tentative full market value, level of assessment, and resulting tentative assessed value. These numbers, once finalized, determine your share of every school, county, town, and special district levy for the 2027/28 tax year.

Tax bills based on this roll arrive:

• October 2027 — first-half school tax bill
• January 2028 — first-half combined county/town/special-district bill

The roll remains tentative for about 14 months while the Assessment Review Commission (ARC) reviews and corrects assessments before the final roll is filed.

Nassau’s tentative notice has six key lines you should compare to last year:

• Full Market Value — the assessor’s estimate of what your home would sell for as of the valuation date (July 1, 2025 for the 2027/28 roll).
• Level of Assessment (LOA) — Nassau’s LOA is typically 1.0% for residential property.
• Tentative Assessed Value — Full Market Value × LOA.
• Transitional Assessed Value — Nassau phases in big assessment changes over multiple years for residential parcels. The transitional value is the actual number used to calculate your bill.
• Tax Class — Class 1 (residential 1-3 family), Class 2 (residential 4+, co-ops, condos), Class 4 (commercial).
• Value Change From [prior year] — the year-over-year change in market value.

If your Full Market Value is more than 10% above what comparable homes in your neighborhood have sold for in the last 12 months, you have a strong case for an ARC grievance.

The ARC accepts residential grievances filed online, by mail, or in person. The form (AR1) is short — typically 1–2 pages — and you can file with or without comparable-sales documentation. Most homeowners file with at least three recent sales from their immediate neighborhood.

• Deadline: March 31, 2027 (extended from the statutory March 1).
• How to file: Online at the ARC website, or by mail to the address on your notice.
• What ARC decides: Whether your tentative value is accurate. If they reduce it, your assessed value drops and your future bills with it. ARC must rule by March 31, 2028.
• If ARC denies: You can appeal via Small Claims Assessment Review (SCAR) within 30 days of the final roll. SCAR requires a $30 filing fee and is heard by an arbitrator.

See our full Nassau grievance guide for the step-by-step, including comp-pulling tactics and what to expect at SCAR if it gets that far.

A few things that confuse Nassau homeowners every January:

• “My value didn’t change. Should I still grieve?” Yes, if the value was inaccurate last year. ARC will review the current tentative against market data; a no-change tentative still gets reviewed if you file.
• “The Notice says ‘Value Change From 1/2/2024: 0’. Does that mean no change?” Yes. The transitional system means a stable Full Market Value can still translate to a different bill if the level of assessment or your transitional value moved.
• “Should I hire a firm or file myself?” If your case is straightforward (clear over-assessment vs comparable sales), DIY filing is fine and free. If your case involves complex valuation (waterfront, unique architecture, recent renovation) or you want to skip the legwork, firms charge ~50% of the first year’s savings.