How to Appeal Your Property Tax Assessment on Long Island: The 2027 Filing Calendar for Nassau and Suffolk

ByPawli Paola Meyer

Nassau County’s window to contest the assessment behind its 2028-29 roll opens January 4, 2027, and closes March 1. Suffolk County’s opens May 1 and closes on the third Tuesday of May, which in 2027 lands on May 18. Both dates sound distant from an October vantage point, yet the part of an appeal that decides the outcome, assembling proof that a house is worth less than the roll implies, goes better in the fall than in a three-week scramble.

Filing costs nothing in either county, and the administrative stage requires no attorney. In Nassau, the Assessment Review Commission says on its own appeals page that it “will never increase the assessment”, so the possible results are a reduction or no change. For Suffolk, News 12 Long Island reported in May 2026 that, according to tax assessment advisor Michele La Grassa of Heller & Consultants, a denied grievance leaves the bill exactly where it was.

Two Counties, Two Calendars

The mechanics split at the county line. Nassau routes every complaint through one body, the Assessment Review Commission (ARC), and takes applications online through a system called AROW. Suffolk has no equivalent: each of its ten towns accepts complaints through its own assessor and Board of Assessment Review, using the state’s Form RP-524, and Brookhaven, for one, ran an online application in 2026 alongside mailed and hand-delivered forms.

Nassau CountySuffolk County
Where complaints goAssessment Review Commission (ARC)The assessor’s office in the town where the property sits
2027 filing windowJanuary 4 to March 1, 2027May 1 to the third Tuesday of May (May 18, 2027); confirm with the town
How to fileOnline, through AROWForm RP-524, or the town’s online version of it
FeeNoneNone for the complaint itself
HearingNot required; the case rests on the documents submittedBoard of Assessment Review hearing; owners may attend
If deniedSmall Claims Assessment Review (SCAR) or State Supreme CourtThe same two options

Nassau has stretched its deadline before. The ARC pushed the 2027/28 cutoff from March 1 to March 31, 2026, which law firm Farrell Fritz called a “firm administrative deadline”, and nothing promises the same relief next time, so March 1 is the safer date to build around. Suffolk’s rule is steadier. Farrell Fritz notes the deadline is always the third Tuesday in May, and Brookhaven’s 2026 instructions returned any submission that arrived before May 1 or after the cutoff.

Nassau’s Commission also embeds a walkthrough video on its appeals page, reproduced below. It covers Nassau’s process; each Suffolk town publishes its own instructions.

Nassau County Assessment Review Commission: How to Appeal Your Assessment (video embedded on the ARC’s own appeals page)

Step One: Work Out What the Roll Implies About Market Value

An assessed value is not a market value. New York requires assessments to be set at a uniform percentage of value, and that percentage may sit well below 100, so the figure on the roll has to be converted before it can be compared with anything a buyer would pay. The state’s instructions for Form RP-524 offer three yardsticks for the percentage: the equalization rate, the residential assessment ratio for one-to-three-family homes, and the uniform percentage printed on the assessment roll. The Tax Department’s form guidance adds that the lowest of the three generally produces the largest reduction.

Flat-lay of folders, measuring tools and coffee for an assessment appeal

The state’s own worked example shows the arithmetic. A property worth $200,000 and assessed at $150,000 is carried at 75 percent of value. If other homes on that roll average 50 percent, the supportable assessment is $100,000, half the market value, and that is the figure a complaint would request. Running it backward works too. On a purely hypothetical roll that assesses at 1 percent of value, an entry of $5,000 implies the assessor sees a $500,000 house. Each town’s actual percentage has to come from its own roll or the state’s equalization listings, never from an illustration.

The comparison also belongs to a particular moment. The state treats the valuation date in most municipalities as July 1 of the prior year, and it advises confirming that date with the local assessor before choosing sales to compare. Nassau’s ARC frames the same first step more simply: set the Department of Assessment’s adjusted market value beside the owner’s own estimate of current market value.

Two cautions travel with the math. A complaint has to cover the whole parcel, and the state’s form is blunt that “you cannot base your grievance only on the assessed value of the land.” The requested number also follows an owner into later stages: the state warns that asking for too little can foreclose a larger reduction, and a SCAR petition cannot seek less than was requested at the board stage.

None of this touches the tax rate. As the New York State Tax Department puts it, “Assessors do not determine your property taxes.” School districts, towns, and counties set their budgets, and the assessment only fixes each parcel’s share of the levy. An owner whose roll figure is accurate but whose bill feels heavy has a question for the taxing bodies, not the assessor.

Step Two: Build the Evidence File

New York law presumes the assessor’s figure is correct, which puts the burden of proof on the owner, according to the state court system’s SCAR guidance. What carries that burden is ordinary paperwork:

  • Comparable sales. Recent sales of similar homes at prices below the value the roll implies. The Tax Department calls these the strongest support for most residential complaints.
  • Purchase or offering price. A recent purchase price for the property itself, or a recent asking price if it was listed.
  • A professional appraisal. Any appraisal the owner already holds counts as evidence.
  • Construction costs and insurance amounts. Both appear on the court system’s list of useful proof of value.
  • Comparable assessments. For an unequal-assessment claim, the assessments and market values of a sample of similar homes on the same roll.
  • Exemption records. If a STAR or other partial exemption was denied or miscalculated, the state treats that as an excessive-assessment ground and asks for a copy of the exemption application; the ARC also reviews denied exemptions. The STAR rules have shifted in ways that catch new owners.
  • Photos and measurements. Dated photographs and measured dimensions document condition and size where the roll’s data looks off. This is general practice rather than a legal requirement.

Format matters for online filing. Nassau’s system accepts Word files, spreadsheets, photos, and scanned images, but not video.

Tools That Make the Evidence File Easier

A few inexpensive tools cover most of the measuring, scanning, and organizing involved.

As an Amazon Associate I earn from qualifying purchases. A commission may be earned if you buy through this link, at no extra cost to you.

Step Three: File Before the Window Closes

Nassau County

Nassau owners file online through AROW during the window. The application asks for basic property information, and the instruction sheets for forms AR1, AR2, and AR3 list the documents required for each property type and claim. Before filing, an owner should confirm that nobody else has done it already: the ARC warns that unresolved duplicate applications are denied, and an owner who signed an authorization for a representative, or whose condo board files on the owner’s behalf, should not file separately. Attorneys, and anyone filing for ten or more properties, must register with the Commission as representatives. The ARC’s workshops page, updated March 2, 2026, says the live sessions for that cycle are complete and links a recording of the slide show.

Suffolk County

Suffolk owners file Form RP-524 with the assessor in the town where the property sits, on or before Grievance Day, when the Board of Assessment Review meets. The state’s grievance procedure page gives the third Tuesday of May for Suffolk and warns that a missed date forfeits both administrative and judicial review for that year. In villages that assess property, a separate RP-524 goes to both the town and the village.

Mail is where the rules diverge. State guidance says mailed complaints must be received by the meeting day, while Brookhaven’s 2026 instructions accepted mail postmarked by the deadline, so the town’s own rule governs, and cutting it close is a gamble either way. Brookhaven’s 2026 online application opened at 12:00 a.m. on May 1 and closed at 11:55 p.m. on May 19, and the town said it strongly encourages online filing. An earlier post on this site covers how the 2026 Suffolk deadline worked.

What Happens After Filing

In Nassau, the ARC reviews applications through professional appraisers and other qualified staff and may offer a reduction, which the owner can accept or decline. Final determinations are issued by March 31 of the following year and appear on the final roll, published the first business day of April. A reduction won on a January 2027 tentative assessment therefore shows up on the April 2028 final roll, part of what Farrell Fritz describes as a lag of nearly two years between filing and tax bills.

Homeowner at a kitchen counter with a laptop and document scanner

Suffolk owners meet a Board of Assessment Review of three to five members appointed by the town’s governing body; Brookhaven’s board has a chairman and four members and operates as a quasi-judicial body. The owner may appear in person or send a representative, the assessor attends formal hearings, and the board mails a written determination. Before the hearing, an owner and the assessor can agree to a lower figure by completing Part Six of the RP-524. Once the board ratifies it, further review closes, so a stipulation belongs only on a number the owner would accept as final.

If the Answer Is No: Small Claims Assessment Review

A denial, or a reduction an owner declines, opens two routes into court. The low-cost one is Small Claims Assessment Review. It covers owner-occupied one-, two-, or three-family homes, excludes most condominiums (Nassau Class One owner-occupied condo units are an exception, per the court system), and requires a prior complaint to the board or the ARC. The petition is due within 30 days of the filing of the final assessment roll, carries a $30 fee, and goes to the county clerk; Brookhaven’s page specifies electronic filing. In Nassau, an owner can file starting the first business day in April, and only after applying to the ARC and declining its offer.

A hearing officer decides the case. The petition can claim an excessive assessment, an unequal one, or both, and the officer may leave the figure alone or lower it, though never below the amount claimed on the petition. An attorney is optional. The trade-off sits in the fine print: filing a SCAR petition waives the right to a full Article 7 proceeding in State Supreme Court. That second route, tax certiorari, is the one for which the Tax Department strongly recommends consulting an attorney.

Questions Owners Ask

Does the appeal have to be repeated every year? Each year carries a new assessment, and the ARC advises filing even while last year’s appeal is still pending.

Quiet municipal hearing room with an oak table

Is a paid grievance service necessary? Neither the ARC, the Board of Assessment Review process, nor SCAR requires one, and the Tax Department says no lawyer is needed to grieve. Paid services exist, and owners considering one should read the fee terms before signing.

How much can an appeal save? News 12 relayed a figure of about $1,500 a year on average from Heller & Consultants, a firm that handles grievances. That number comes from a business with an interest in filings, not an official tally, and a fairly assessed home may gain nothing.

Does an appeal fix a bill that feels too high? Only when the assessment is the problem. The path from roll to bill has many parts: in March 2025, TBR News Media reported on Brookhaven’s receiver of taxes explaining to the Three Village Civic Association how a prior-year omission of about 30 properties from the town’s figures fed into that year’s school tax bills. “A mistake happened, but it didn’t cost you any money,” Receiver of Taxes Louis Marcoccia said.

What if a sale is coming? News 12’s source said a lower assessed value can make a home more appealing to buyers by easing the carrying cost. A related post on this site looks at how the gap between assessed and market value plays into pricing a sale.

This is for informational purposes only — consult a licensed attorney or financial advisor for your specific situation. Deadlines, forms, and procedures change, so confirm dates with the Nassau ARC or the relevant town assessor before filing.

Real estate markets change. For current listings and market data, contact Maison Pawli at maisonpawli.com/about/.

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