Nassau County Property Tax Grievance Guide
A property tax grievance in Nassau County is an appeal of your property’s assessment to the Nassau County Assessment Review Commission (ARC). This guide explains the current filing cycle, what ARC reviews, and what homeowners should expect.
Reviewed by Chris Ambrosio, CPA · Updated October 7, 2026
What is a Nassau County property tax grievance?
A Nassau County property tax grievance is a request for ARC to review the County’s assessment of your property. The grievance challenges the assessment value rather than simply arguing that the tax bill is too high. Nassau County publishes a new tentative assessment each year, and the appeal must be filed during the applicable ARC filing period.
How the Nassau County grievance process works
Review the assessment
Confirm the property, parcel information, current assessment and filing cycle before preparing the appeal.
Prepare the grievance
Build the filing using the property information and relevant assessment or market evidence for the current cycle.
File with ARC
The appeal is submitted to the Nassau County Assessment Review Commission during the open filing window.
Wait for ARC review
ARC reviews timely filed applications and later issues a determination. The review process can continue well after the filing deadline.
Do you have to hire a property tax grievance company?
No. Nassau County states that homeowners may file an appeal themselves and that ARC does not charge a filing fee. A representative is optional. GrieveItNow is a paid service for homeowners who want us to handle the research, preparation, authorization and filing process for them.
Why does the assessment year look one year ahead?
Nassau County’s assessment calendar operates ahead of the tax bills that eventually use the assessment. That is why a grievance filed during the January–March 2027 ARC window concerns the 2028/29 assessment, not 2027/28.
What authorization is required for a representative?
Nassau County requires a signed authorization when someone files on behalf of a property owner. GrieveItNow collects the homeowner’s authorization electronically after payment and keeps the signed authorization with the client record.
How much does GrieveItNow charge?
GrieveItNow charges a flat $99 fee for research, preparation and filing of the Nassau County grievance. We do not take a percentage of the homeowner’s savings.
More Nassau County homeowner guides
- How to grieve your Nassau County property taxes
- Nassau County grievance deadline 2027
- How to find your Nassau County Parcel ID
- Flat fee vs. percentage-of-savings grievance pricing
- What happens after an ARC filing
- Nassau County AROW guide
- How comparable sales work in a Nassau grievance
- Nassau County level of assessment explained
- Printable Nassau grievance checklist
- Nassau County grievance FAQ
Official Nassau County resources
For authoritative filing dates and ARC rules, homeowners should also review Nassau County’s official Assessment Review Commission information. County deadlines can change, so official County notices control if they differ from a third-party website.