Do you open your Nassau County property tax bill and feel like you're paying too much? You're not alone, and you don't have to accept it.
The single most effective way to lower your property tax bill is to challenge your home's assessed value by filing a property tax appeal, also known as a tax grievance. A lower assessment directly translates to a lower tax bill.
This guide will walk you through the entire Nassau County appeal/grievance process step-by-step, from understanding the deadlines to gathering the proper evidence to win your case.
Why You Should Strongly Consider a Grievance This Year
On the first business day of January each year, Nassau County releases its tentative assessment roll — a list of properties in the county and their assessed values. It's January 2, 2026, for next year. You have a limited window, from that day until the March deadline, to file a grievance. Note that you may also receive a notice of the new assessment roll by mail.
Your home's assessed value is a critical factor when calculating property taxes. Your tax bill is a percentage of this value, so a higher assessment means you'll owe more taxes. If you believe the department has overvalued your property, filing a Nassau County property tax appeal allows you to contest the assessment and potentially reduce what you owe.
To challenge your property's assessment, you must file a grievance between the day the tentative assessment roll is published and the Nassau County property tax appeal deadline (usually early March).
Here’s why this year is especially critical:
1. The Ongoing Assessment Freeze: Nassau County has frozen most property values since the 2020-21 tax year. This freeze is expected to last through 2026. If your property's market value has stagnated or dropped while others have risen, you could shoulder an unfair tax burden. The appeal is your only means of correcting this.
2. Your Assessment Seems Higher Than Your Neighbors: Use the county's Land Records Viewer to look at homes similar to yours in size, style, and condition. If their assessed values are lower than yours, you have a strong case for an appeal.
3. Your Property Has Issues: Is your roof old? Is your kitchen outdated? Does the property have structural issues? The county's assessment and Land Records Viewer don't always account for significant recent problems that could've lowered your assessed value.
Note that you cannot appeal your tax rate, but you have the right to appeal your assessed value each year. A successful grievance can save you thousands of dollars over time. Not convinced? Here are other common reasons to appeal property taxes in Nassau County:
Step-By-Step Appeal Process
Here's how to appeal Nassau County property taxes.
Step 1: Receive and Review Your Property Assessment
Once the county publishes a tentative assessment roll, use the Land Records Viewer tool to check your property's assessed value. You may receive a notice of the publication by mail.
Compare the property's value in the roll with what you believe to be the actual market value. If the assessed value is higher, prepare to contest it to ensure you only pay your fair share.
Step 2: Gather Documents and Evidence to Support Your Case
You'll need to substantiate that your property's assessed market value is higher than its actual value. The most effective evidence to support your Nassau County appeal for property tax includes:
Comparable sales prices of similar properties: Use the Land Records Viewer or Sales Locator tool to look up and compare sales prices of properties similar to yours in your area.
Professional appraisals: Ensure they are dated the same day as the assessment you're protesting.
Photos of major issues: Take pictures of anything that can reduce your property's value, such as structural damage.
Step 3: File Your Tax Grievance
To officially appeal your assessment, you must file an "Application for Correction of Assessment" with the Assessment Review Commission (ARC).
Crucial 2026 Deadlines:
January 2, 2026: Tentative Assessment Roll is published. The appeal window opens.
March 3, 2026:The standard deadline to file your appeal. Do not miss this date.
How to Submit Your Application:
Online via the Assessment Review on the Web (AROW): Once you register for an ARC account, you fill out and submit the Application for Correction of Assessment form inside AROW. The system also allows you to attach the relevant evidence.
By mail: Call ARC at 516-571-3214 to request the tax grievance application form be mailed to you. After filling out the form, you send it back (plus all supporting documents) to ARC at 240 Old Country Road, 5th Floor, Mineola, NY 11501.
Pro-tip: the mail must be postmarked by the USPS or a private IRS-designated carrier before the application deadline, and use a return receipt to have proof of delivery.
In person: Visit ARC offices at 240 Old Country Road, 5th Floor, Mineola, NY 11501.
In 2025, the initial window to file Nassau County tax grievances was from January 2 to March 3, before the deadline was extended to April 1.
In 2026, the Nassau County Department of Assessment will publish the tentative assessment roll on January 2, with appeals accepted from January 2 through March 2. However, we expect the county to push back the deadline another month.
What Happens After You File?
The timeline and outcomes after you file:
The ARC will review your tax grievance and issue a final determination between the filing date and March 31 of the following year. The agency will offer a property assessment reduction or leave it unchanged. The ARC will not raise your assessment due to a failed grievance.
Some cases are resolved quickly, while others take many months. If ARC issues its final determination and you accept it before the final roll is locked (typically April 1), the change will appear that year. Otherwise, it will carry over to the next roll.
If you disagree with ARC’s decision:
If you disagree with ARC's decision or reduction offer, you can file a Small Claims Assessment Review (SCAR) at the Nassau County Clerk's office. The $30 SCAR filing fee is refundable if your appeal succeeds. And if you're using Ownwell, we'll pay the $30 SCAR filing fee.
Should You File on Your Own or Hire a Professional?
Filing a Nassau County residential or commercial property tax appeal is something nearly any homeowner or property owner can do. The real question is about time, effort, and maximizing your chance of success. Here’s a breakdown:
Factor | DIY Appeal | Hiring a Professional Firm (like Ownwell) |
|---|---|---|
Cost | Free (except for your time and appraisal fees). | No upfront fees. A 25% of the tax savings if we win. |
Time | Can be time-consuming: researching comps, gathering evidence, filling out forms. | Minimal effort required. We handle everything from start to finish. |
Expertise | You are responsible for building a compelling, evidence-based case. | We are experts in Nassau County's market and know exactly what the ARC and SCAR look for. |
Success Rate | Depends on the quality of your evidence and argument. | Our expertise and data-driven approach significantly increase your chances of winning a reduction. |
Lastly, we can also assist you in filing retroactive property tax exemptions and managing all your real estate taxes, including special assessment taxes. File property tax appeals with Ownwell without upfront fees. You only pay us if we save you money.
Nassau County Property Tax Appeal FAQs
1. What is the difference between a tax appeal and a tax grievance?
In Nassau County, the terms are used interchangeably. Filing a "grievance" with the Assessment Review Commission (ARC) is the official first step in the "appeal" process.
2. How does an assessment affect my property tax bill?
Your tax bill is based on your property’s assessed value — the higher the assessment, the higher your taxes.
3. Will my assessment go up if I file a tax grievance?
No. Neither the ARC nor the STAR can raise your assessment when you file a grievance. They can only lower it or leave it unchanged. There is no risk of your taxes increasing because you filed.
4. Can I challenge the ARC's decision?
Yes, if necessary, you can challenge ARC’s decisions through SCAR appeals; however, a $30 filing fee applies, which is reimbursed if you win your case.
5. When will a reduction show on my bill?
If ARC’s determination posts before the roll is finalized (around April 1), it appears in that year’s roll; otherwise, it applies to the next roll.
