Quick Summary: Nassau County homeowners must file an ARC property tax grievance during the annual filing window that opens in early January and closes on a specific deadline set by the County. For the 2028/29 assessment year, the filing window is January 4, 2027, through March 1, 2027. That deadline comes well before the school and general tax bills tied to that assessment are mailed, so do not wait until a bill arrives to take action.  A grievance challenges the property assessment, not the tax rate or an already-issued tax bill. It may be appropriate where the County’s valuation appears excessive or where there is an issue concerning the property’s tax classification or exemption status.

 

At the Law Offices of Laurence Rogers, we help Nassau County, NY homeowners understand the timing, paperwork, and next steps involved in challenging an overassessment. A property tax grievance may be appropriate if you believe the County’s valuation of your property is excessive.

What Is the Nassau County ARC Filing Deadline?

ARC is the Nassau County Assessment Review Commission. It is the independent County agency that reviews timely filed applications asking for a correction to a property assessment. The important word is timely: homeowners have a limited annual opportunity to challenge the new assessment.

For the upcoming 2028/29 assessment year, Nassau County’s published filing period runs from January 4, 2027, to March 1, 2027. An online filing submitted through the County’s AROW system can be filed through 11:59 p.m. on March 1, 2027. Because dates can change from year to year based on the calendar or County action, homeowners should confirm the exact deadline for the assessment year at issue rather than assume every filing period ends on the same date.

This is why “sometime in winter” is not a workable deadline strategy. Winter includes a short but critical filing window, and waiting until late February can leave too little time to review your assessment, gather sales information, prepare the correct application, and address unexpected issues.

ARC Reviews Assessments, Not Your Existing Tax Bill

One of the most common sources of confusion is the difference between an assessment and a tax bill. ARC does not decide local tax rates but reviews the property's assessment value and considers whether a correction to this value is appropriate.

Your tax bill is calculated later by applying the relevant tax rates to your taxable assessed value. Those rates are set through the budget processes of the applicable tax districts. In other words, an ARC grievance is a challenge to the assessment that will be used to calculate future taxes, not a request to reopen a bill that has already arrived.

For a closer look at whether an appeal may make sense for your home, visit Property Tax Grievances.

How the Assessment Year Maps to Future Tax Bills

The timing is counterintuitive at first. A homeowner files an ARC grievance early in one calendar year, but the assessment being challenged generally affects tax bills issued later. Understanding that mapping helps prevent missed opportunities.

For example, the assessment grievance filed between January 4 and March 1, 2027 concerns the 2028/29 assessment year. ARC reviews applications after the filing period. The County’s final assessment roll for that year is scheduled to be published in April 2028. The school tax bill based on that assessment is expected in October 2028, followed by the general tax bill in January 2029.

That sequence explains why filing after receiving a future bill is too late for the annual ARC grievance. By then, the filing period for the underlying assessment has already passed. Nassau County homeowners should think ahead: the deadline in early 2027 concerns bills they may not see until late 2028 and early 2029.

What Happens If You Miss the ARC Filing Window?

Missing the ARC deadline can have serious consequences. Once the filing period for that assessment expires, you generally cannot use ARC to contest that year’s assessment. A homeowner may still have the ability to file for a later assessment year when the next filing period opens, but that does not restore the lost chance to challenge the prior year through ARC.

This is especially important for families budgeting around Nassau County property taxes. A missed deadline can mean living with an assessment you wanted reviewed while waiting for the next annual opportunity. It can also limit the options available after ARC completes its review, including a potential Small Claims Assessment Review (SCAR) petition, which has its own separate deadline.

Filing on time preserves options. It does not guarantee a reduction, but it gives the Assessment Review Commission the opportunity to consider the claim and allows homeowners to evaluate the appropriate next step after a determination.

How the Law Offices of Laurence Rogers Can Help

The Law Offices of Laurence Rogers serves homeowners throughout Nassau County, including Valley Stream, Lynbrook, Rockville Centre, Elmont, and nearby Long Island communities. We take a direct, practical approach to property tax grievance matters: the attorney who speaks with you is the attorney handling the work—not a file passed from one person to another.   

 

We can help you understand whether a Nassau County ARC filing is appropriate, what assessment year is involved, and what deadline applies. We also assist homeowners with the next stages of the process when an appeal warrants further review. Legal issues are often less intimidating when someone explains the sequence plainly and focuses on the deadline that matters now.  

 

We handle Nassau County property tax grievance matters for a flat fee rather than a percentage of any reduction obtained.

 

We also handle Village assessments grievances, which follow a separate grievance process and filing calendar from Nassau County. In many Nassau County villages, grievance dates occur earlier in the year, often in early to mid-February.  Homeowners who wish to challenge a village assessment should confirm the applicable village deadline separately. Upon request, we evaluate and prepare village grievances where a separate filing is warranted.

FAQ

When is the next Nassau County ARC filing deadline?

For the 2028/29 assessment year, applications are due by March 1, 2027. The filing period opens January 4, 2027.

Can I wait until I receive my property tax bill to file a grievance?

No. The ARC filing period closes before bills based on that assessment are mailed. The 2028/29 assessment is tied to school bills expected in October 2028 and general tax bills expected in January 2029.

Can ARC lower my tax rate?

No. ARC reviews the assessed value of the property. Tax rates are set separately by the applicable tax districts.

What if I miss the March 1 deadline?

You generally lose the opportunity to challenge that assessment through ARC. You may be able to file for the next assessment year when its new filing window opens.

Do I need a lawyer to file an ARC grievance?

You may file on your own, but legal guidance can help when you need assistance understanding the assessment, supporting a claim, or evaluating a later appeal. To discuss your situation, visit our Contact page or call (516) 253-4230 for a complimentary consultation.