A co-op overpaid property taxes for 40 years. New York returned six years of it.

NYC's Class 2 property tax is a single line on a bill, calculated from data the Department of Finance holds and the board is not required to audit. When that data contains a clerical error — a wrong square footage, a misapplied income figure — the building overpays. New York law gives boards the power to challenge those calculations. It does not require them to use it.

How New York arrives at your co-op's property tax bill.

Under Real Property Tax Law § 581, New York City values co-op and condo buildings as though they were rental buildings, not ownership units. The city derives a market value from the income of comparable rental properties, typically sourced from the Real Property Income and Expense statements that large buildings file annually with the Department of Finance. From that derived market value, the city applies an assessment rate to produce the assessed value, then applies the Class 2 tax rate to generate the bill. The gap between DOF market value and actual sales price is often substantial; a July 2026 post on this site documented a Comptroller-measured median ratio of 20.6 percent. But that is a feature of the income-approach methodology, not an error in the data. The clerical error problem is different: it is a mistake in the inputs themselves. A square footage figure recorded incorrectly when a building's record was first established will produce a wrong tax calculation year after year, compounding through every assessment cycle, because no one is required to verify that the number on file matches the building's actual dimensions.

What boards are empowered to do when the number is wrong.

Two paths exist. The first is the Tax Commission appeal. Each January 15, the Department of Finance publishes the Tentative Assessment Roll, listing the assessed value of every property in the city. A board has until March 1 of that year to file an Application for Correction of Tentative Assessment with the Tax Commission. The commission reviews applications, schedules hearings, and either adjusts the assessment or upholds it. This path addresses valuation disputes: cases where a board believes the income-approach methodology produced an inflated market value. The process is purely permissive. The second path is an Administrative Review Application filed directly with the Department of Finance under Administrative Code § 11-206. A clerical error correction does not require a Tax Commission proceeding; it is a direct request to the Department of Finance to fix a computation mistake or data-entry error. An Upper West Side co-op board used this second path to correct a square footage figure, recorded by the Department of Finance as 119,228 square feet, when the building's actual floor area was 93,759 square feet, a figure the city had held on file for more than four decades.

What boards are required to do when the calculation looks wrong.

Nothing. Business Corporation Law § 624 requires co-op corporations to make certain financial records available to shareholders upon written demand, but it imposes no duty to monitor the city's assessment records, no duty to review the Tentative Assessment Roll each January, and no duty to compare the square footage the Department of Finance holds on file against the building's actual dimensions. Real Property Law § 339-w extends a financial-disclosure obligation to condo boards: unit owners may inspect books and records on demand. That obligation does not reach assessment review. Neither statute treats the Tentative Assessment Roll as a document the board is responsible for examining. The Tax Commission's March 1 deadline passes uncontested for most of the city's co-op and condo buildings each year, not because every assessment is correct, but because the law imposes no obligation to check. A board that has never reviewed its DOF square footage record is not in breach of any duty. A board that discovers a 40-year-old error the day before it intends to sell the building is in exactly the same legal position as a board that monitored the record annually.

Six years is the ceiling, whatever the error's age.

The Department of Finance's clerical error administrative review rules, as in effect at the time of this correction, limited refund corrections to six years from the date of each overpayment; DOF rule amendments effective January 5, 2025 reduced that window to three years for applications filed after that date. The Upper West Side co-op that corrected its square footage from 119,228 to 93,759 square feet (a reduction of more than 21 percent in the recorded floor area) had been paying taxes on the wrong number for more than 40 years at the time of correction. When the board submitted the Administrative Review Application, the Department of Finance adjusted the assessment going forward. The refund covered the six most recent tax years. The preceding 34 years of overpayment generated no claim. The six-year ceiling operates without regard to when the error originated, how long it ran, whether the board had any reason to discover it sooner, or whether the error was the city's own data-entry mistake. Boards that inherit an error from a prior administration have the same six-year recovery window as boards that introduced one themselves.

The managing agent who missed it faces no professional consequence.

Most co-op and condo boards in New York rely on a managing agent to handle operational compliance. Property tax monitoring: reviewing the Tentative Assessment Roll, verifying square footage records, and filing Tax Commission appeals on time, all fall within the scope of work a managing agent typically takes on by contract. A managing agent that fails to perform this work, or performs it incorrectly, is in breach of contract. The board's remedy is civil litigation. There is no license to revoke. In New York, a managing agent of a residential co-op or condo holds no state-issued credential and is not regulated by any licensing authority. A barber who misidentifies a hair product needs a license renewal. A managing agent who fails to catch a DOF clerical error for 40 years needs nothing the state can revoke. Senate Bill S.71, sponsored by Senator Brian Kavanagh, would create a licensing regime for residential managing agents. The bill passed the Senate this session and has no Assembly companion bill. The accountability mechanism this situation most directly illustrates is not on a path to becoming law. Read more at the managing agent licensure gap issue page.

Bottom line.

New York gives co-op and condo boards two instruments for challenging a property tax assessment error: the Tax Commission appeal by March 1 and the Administrative Review Application to the Department of Finance for clerical corrections. Neither instrument comes with a statutory obligation to use it. When a board misses an error or inherits one from a prior administration, DOF clerical error rules capped the refund at six years under rules in effect at the time of this correction, regardless of how long the error ran; January 2025 rule amendments have since reduced that ceiling to three years for new applications. The managing agent that should have been monitoring the assessment record holds no state license and faces no regulatory sanction for the oversight. The result is a structural gap: the owners of New York's 14,062 co-op and condo buildings have no statutory protection against assessment errors their boards are not required to find. The city, for its part, is under no obligation to notify a board when the square footage on file differs from the building permit. Six years is what the law allows. The rest is what the law permits to stay.

Companion resources: Managing agent licensure gap · How NYC values co-ops under RPTL § 581 · Write to your state legislator about S.71 · 421-a abatement calculator