Travis Bunn

Founder, AppealDesk · Published July 21, 2026

Nassau County Property Tax Grievance Deadline: 2026 and 2027 Dates

Updated July 2026 · 8 min read

Why Nassau County Runs on a Different Calendar Than the Rest of New York

In most New York communities, assessment complaints are heard by a town Board of Assessment Review on Grievance Day, which the state Department of Taxation and Finance notes is the fourth Tuesday in May in most places. Nassau County is the big exception. Assessment review is countywide, handled by the Nassau County Assessment Review Commission, and the filing window runs from the publication of the tentative assessment roll in early January to a statutory deadline of March 1.

Nassau also works two tax years ahead. The grievance you file in early 2027 challenges the 2028/29 tentative roll, not the bill that arrives next month. The window that closed on March 31, 2026 covered the 2027/28 roll, which becomes the basis for school tax bills mailed in October 2027 and general tax bills in January 2028. Filing early in the cycle is how you get ahead of a bill that is otherwise locked in almost two years out.

The Nassau County Grievance Timeline

There is no fee to file a grievance with ARC, and your assessment cannot be increased because you filed. If ARC does not reduce your assessment, the SCAR route puts your case in front of a court-appointed hearing officer. The state Department of Taxation and Finance lists SCAR eligibility as owners of one to three family residential dwellings or qualifying vacant land, with a $30 filing fee.

Missed the March 2026 Deadline? Here Is What You Can Do Now

If you did not file by March 31, 2026, you cannot challenge the 2027/28 roll. Your next opportunity is the 2028/29 window opening in January 2027. That is not wasted time if you use it:

• Pull your property record now. Check the square footage, lot size, bedroom and bathroom counts, and condition the county has on file. Errors in the record are the easiest grounds to document.
• Track comparable sales through the fall. Sales closing in 2026 will be the evidence that matters when the January 2027 window opens.
• Calendar the first week of January. Filing early beats scrambling against the March deadline, and you do not need to wait for an extension announcement that may never come.

Suffolk County Is a Different System With a Different Deadline

Long Island neighbors, opposite calendars. Suffolk County has no countywide review commission. Grievances are filed with the assessor in whichever of Suffolk’s ten towns the property sits in, and the filing period runs from May 1 to Grievance Day, the third Tuesday in May. In 2026 that deadline was May 19. Miss it and the next chance is May 2027.

One more wrinkle for both counties: incorporated villages that do their own assessing run separate grievance calendars for village taxes, with village review boards typically meeting the third Tuesday of February. A county grievance does not touch your village assessment, so village residents may need to file twice.

How AppealDesk Fits In

Contingency firms on Long Island typically take a percentage of your first year’s savings. AppealDesk builds the same core evidence, comparable sales analysis and a ready-to-file packet, for a flat $49, and you keep every dollar you save. Start with the free analysis: if your assessment looks fair, you will know without spending anything, and if it looks high, you will have the evidence ready for the January window.

For the full county picture, see our Nassau County appeal guide and the New York state appeal overview. Deadlines for the rest of the state are in our New York deadline guide.