If you believe your home is overvalued, a Nassau County tax grievance is the free administrative challenge you file with the Assessment Review Commission (ARC) between January 2 and the annual deadline. For the 2026 filing season, that deadline has been extended to March 31.1Nassau County, NY. Assessment Review Commission You do not need a lawyer, you do not pay a filing fee, and if ARC agrees your assessed value is too high, the reduction lowers the taxes calculated on that value for the upcoming year.
When and How to File
The standard filing window runs from January 2 to the first business day of March. The 2026 extension to March 31 is specific to that year; extensions are not guaranteed, so treating early March as your working deadline is safer than relying on extra time.1Nassau County, NY. Assessment Review Commission Late applications are rejected regardless of the strength of your evidence, and there is no appeal from a missed deadline. If you miss it, you wait a year.
Two filing methods are available. The Assessment Review on the Web portal (AROW) accepts electronic submissions and issues an appeal number immediately, with a confirmation email following shortly after. Save that confirmation. It is your proof of timely filing. You can also mail a completed Form AR1 to the Assessment Review Commission at 240 Old Country Road, 5th Floor, Mineola, NY 11501. If you mail it, the postmark must be no later than the filing deadline, and certified mail with return receipt gives you proof the commission received it.2Hempstead Town, NY. Challenge and Lower Your Taxes
Grounds the Law Allows
New York Real Property Tax Law limits grievances to four grounds, and you only need to establish one.3New York State Senate. New York Code RPT 524 – Complaint on Assessment For residential homeowners, two matter most:
- Excessive assessment, meaning the value on the roll exceeds your property’s actual market value. This is the most common ground, and it also covers cases where ARC failed to apply a partial exemption you qualify for, such as STAR or a veterans exemption.4New York State Senate. New York Real Property Tax Law 522 – Definitions
- Unequal assessment, meaning your property is valued at a higher proportion of market value than comparable homes on the same roll. If the county generally assesses homes at 1 percent of market value and yours comes in higher, this ground fits.4New York State Senate. New York Real Property Tax Law 522 – Definitions
The remaining two grounds, unlawful assessment and misclassification, cover property that sits outside the taxing jurisdiction, qualifies for a full exemption that was not applied, or has been assigned to the wrong tax class. Both are uncommon for a typical single-family homeowner.
Nassau County residential property falls into Class 1, and a statutory cap limits how fast a Class 1 assessment can rise: no more than 6 percent in a single year and no more than 20 percent over five years, excluding new construction and renovations.5Nassau County, NY. Nassau County LandRecord Lookup The cap softens year-to-year jumps but does nothing to fix an assessment that is wrong to begin with.
Filling Out Form AR1
Form AR1 is the official grievance application. You can download it through AROW, request a copy from ARC, or call (516) 571-3214.6Town of Oyster Bay. Grievances You will need your property’s Section, Block, and Lot numbers, which appear on your tax bill and in the county’s land records.
The form asks for your own estimate of market value as of January 2 of the assessment year. Treat that number as evidence, not a guess.3New York State Senate. New York Code RPT 524 – Complaint on Assessment The strongest support is recent comparable sales: actual closings of similar homes in your neighborhood near the taxable status date. Look for properties close to yours in square footage, lot size, age, condition, and location.
Three to five strong comparables beat a long list of weak ones. A home that sold two blocks away three months before the status date carries much more weight than one that sold two towns over a year earlier. If your property has condition problems that drag down value, such as a cracked foundation, flood damage, or proximity to a commercial lot, document them with photos and repair estimates.
Everything on the form is submitted under certification. Providing false information about purchase prices, improvement costs, or your value estimate can trigger penalties under the penal law.3New York State Senate. New York Code RPT 524 – Complaint on Assessment
What Happens After You File
ARC reviews your evidence against the county’s records and its own sales data. The review is administrative; there is no hearing at this stage unless the commission requests one. You wait for a written decision, which typically arrives between spring and early fall of the filing year. ARC does not publish a guaranteed turnaround. AROW filers can check status through the portal.
Three outcomes are possible: a full or partial reduction, no change, or a dismissal. If ARC offers a reduction smaller than you asked for, you decide whether to accept it or pursue further review. Accepting settles the matter for that tax year, and the lower assessment flows into your upcoming bills.
If ARC Says No: Small Claims Assessment Review
Homeowners dissatisfied with ARC’s decision can escalate to a Small Claims Assessment Review (SCAR) proceeding. SCAR is an informal hearing before a trained hearing officer and is substantially less expensive than a formal tax certiorari lawsuit.7New York Courts. Small Claims Assessment Review (SCAR)
To qualify, the property must be an owner-occupied one-, two-, or three-family home used exclusively for residential purposes. Unimproved residential land too small to build a one-to-three-family structure on also qualifies. The property’s equalized value cannot exceed $450,000, unless the total reduction you are requesting is 25 percent or less of the assessed value. You must have filed with ARC first, and you cannot request a lower assessment through SCAR than what you asked for in the grievance.8New York State Senate. New York Real Property Tax Law 730 – Procedure to Obtain Review by Small Claims Assessment Review
The petition goes to the Nassau County Clerk’s office within 30 days of the final assessment roll being published. That is not 30 days from when the ARC decision reaches your mailbox, which is an easy mistake.9Sea Cliff, NY. Small Claims Assessment Review The filing fee is $30.7New York Courts. Small Claims Assessment Review (SCAR) At the hearing you present the same kinds of evidence used with ARC, and the hearing officer issues a binding determination.
How a Reduction Changes Your Tax Bill
A reduction lowers your assessed value, which lowers the property taxes calculated on that value for the upcoming fiscal year. The dollar savings depend on the size of the reduction and the combined rate applied by your school district, town, and county. Even a modest cut can translate to hundreds of dollars off the annual bill.
If you win through SCAR after paying taxes at the higher assessment, keep paying as billed until a corrected bill arrives. The Nassau County Treasurer’s Office recalculates what you owe and refunds the overpayment.2Hempstead Town, NY. Challenge and Lower Your Taxes Reducing your own payments in anticipation of a win creates delinquency penalties.
If your taxes are paid through a mortgage escrow, contact your servicer once your reduction is confirmed. Lenders run an annual escrow analysis, and a lower tax amount should shrink your monthly escrow payment. If the lender has already collected more than needed, the surplus is usually refunded or applied to future payments. That may not happen until the next review cycle, so a call can speed it up.
Hiring a Representative or Grievance Firm
You can authorize an attorney or other representative to file the grievance and appear for you. The written authorization becomes part of the application and must be dated within the same calendar year as the filing.3New York State Senate. New York Code RPT 524 – Complaint on Assessment The same rule applies to SCAR petitions: a representative can file, but only with a written authorization from the property owner attached to the petition.8New York State Senate. New York Real Property Tax Law 730 – Procedure to Obtain Review by Small Claims Assessment Review
Many Nassau County homeowners use tax grievance firms that work on contingency, typically charging around 25 percent of the first year’s tax savings. You pay nothing if the firm does not win a reduction. The arrangement removes financial risk, though firms handle hundreds of cases at once. A homeowner willing to research comparable sales and document condition issues can often do as well filing alone, particularly where the overassessment is obvious. The process was designed to work without professional help.
File Every Year
A successful grievance only affects the year you file. Nassau County updates property values annually, so your assessment can climb back up the following January even after a reduction. Each year is a fresh determination with no carryover. The 6-percent cap limits how fast the number can rise, but it does not keep the number accurate.5Nassau County, NY. Nassau County LandRecord Lookup Filing every year is the only way to keep your assessment aligned with what your home would actually sell for. The filing is free, AROW makes it quick, and the worst outcome is no change.