May 17, 2026 · Updated May 17, 2026
Suffolk County homeowners have until Tuesday, May 19, to formally challenge their property tax assessments, and missing the deadline means waiting until 2027. The filing period covers all 10 Suffolk townships, from Babylon to Islip to Riverhead. Tax attorneys say the process takes less than an hour and can save hundreds or thousands of dollars annually, making it one of the most underused but highest-impact moves Long Island homeowners can make.
Suffolk County homeowners have until 5 p.m. Tuesday, May 19, to formally contest their property tax assessments. Miss the deadline, and the next chance is May 2027.
The grievance window covers all 10 Suffolk townships: Babylon, Brookhaven, East Hampton, Huntington, Islip, Riverhead, Shelter Island, Smithtown, Southampton, and Southold. According to News 12 Long Island, the filing period opened May 1, leaving property owners just 13 business days to submit a complete appeal. The state requires that filings be received, not merely postmarked, by Tuesday's cutoff.
Homeowners file Form RP-524, the New York State Complaint on Real Property Assessment, with the assessor's office in the town where the property sits. The form asks for basic property information, the applicant's requested new assessed value, and supporting evidence, typically a recent comparable sale or a licensed appraisal.
Tax grievance consultants say the paperwork takes under an hour for a straightforward residential property. The filing fee is waived at the town level; many firms work on contingency, taking a percentage of any reduction secured.
Farrell Fritz, a Long Island law firm that tracks the process annually, noted in a client alert that the Suffolk County filing window began May 1, 2026, giving property owners a short 13 business days to file a complete appeal. The firm emphasized that late filings are not accepted under any circumstances.
Property taxes are Long Island's most persistent residential grievance, regularly ranking the region among the highest-taxed suburbs in the country. Nassau County operates on a rolling assessment system with a different calendar; Suffolk's annual May deadline is the primary pressure point for south fork and north shore homeowners alike.
Dozens of tax reduction services operate on Long Island, and many are processing last-minute filings through Monday. GrieveItNow, a local filing service, confirmed that the May 19 deadline applies to all 10 towns and that property owners should submit supporting documentation alongside the RP-524 form.
Homeowners who believe their assessed value is higher than the home's actual market value are the primary candidates for a reduction. A house assessed at $600,000 in a neighborhood where comparable sales have settled at $530,000 could be eligible for a lower bill, potentially saving several hundred dollars per year.
After the grievance deadline, each town's Board of Assessment Review holds hearings, typically in June. Applicants receive a determination letter. If the board denies the grievance, the property owner can escalate to Small Claims Assessment Review, a court proceeding that costs $30 to file and does not require an attorney.
Most cases settle before reaching that stage, according to tax attorneys who handle the process regularly. A reduction is not guaranteed, and the percentage of successful grievances varies by town and by how accurately the initial assessment was made.
Filings go to the individual town assessor's office. Key locations:
Forms can be mailed but must arrive by Tuesday. Filings postmarked May 19 that arrive Wednesday will not be accepted for the 2026 cycle.
The same Tuesday brings school district budget votes across Suffolk. West Islip High School will host polls from 6 a.m. to 9 p.m., as will Islip High School for the Islip Union Free School District. East Islip residents who registered by Monday, May 18, are also eligible to vote that day.
The Babylon Union Free School District board approved a 2.87 percent tax levy increase for the 2026-27 school year, keeping the budget under the state cap while maintaining current programs.
Property owners who want to reduce their assessment before that levy takes effect have fewer than 48 hours to act. Complete Form RP-524 and deliver it to your town assessor's office before 5 p.m. Tuesday, May 19. The state instruction is plain: late filings are not accepted.
