Nassau County, N.Y.Good GrievesSources reviewed September 20, 2026

Co-op and condo tax grievances in Nassau County

Apartment owners in Nassau County are assessed in two quite different ways. A condo is its own parcel; a co-op is a share in a building. That difference decides who can appeal, what evidence counts, and what an individual owner can do.

Co-ops: one building, one assessment

A cooperative corporation owns the building, and shareholders hold shares and a lease for their apartment. The County assesses the property as a whole. Its FAQ says there is only one assessment, which the corporation’s board of directors may appeal, and that individual shareholders cannot appeal it.

The County places cooperative apartment properties in Class 2 and says their assessments are based on the market value of the property as a whole, as if it were operated as a rental. In other words, the price of shares in your building is not the measure the County uses. The County also publishes a different level of assessment for Class 2 than for Class 1 homes, which is one reason a co-op’s assessed value cannot be compared directly with a house’s.

The building’s tax bill is the corporation’s, and shareholders generally bear it through maintenance. A reduction the board wins affects the building’s taxes; how that is reflected for each shareholder is a matter for the board.

What a co-op shareholder can do

• Ask whether the board files. Ask the managing agent whether the corporation appeals its assessment each year, who represents it, and what came of recent filings. Boards answer to shareholders, and this is a reasonable question at an annual meeting.
• Ask how a reduction is handled. If the building’s taxes fall, ask how the saving, or any refund for a past year, is applied to shareholders.
• Apply for exemptions you qualify for. New York State says municipalities are authorized to extend the senior citizens’ exemption and the disability exemption to co-op shareholders, with the benefit reflected as an adjustment to monthly maintenance, and may extend the alternative veterans’ exemption to co-ops. Nassau County’s senior and disability applications ask co-op owners for their certificate of shares.

Our guides to the senior citizens’ exemption, the veterans’ exemptions, and the disability exemption cover eligibility. Confirm with the Department of Assessment which ones apply to your building.

Condos: each unit is its own parcel

A condominium owner owns the unit outright, with a share of the common areas, and the unit is assessed and billed on its own. That means a condo owner has standing to appeal. It also means the board may appeal for all units at once: the County says condominium boards may appeal on behalf of unit owners, and asks a board filing for several units in the same development to file a single appeal covering them.

The risk is overlap. The County’s appeal instructions say you should not file for yourself if your condominium’s board of managers files for you, and that unresolved duplicate applications will be denied. Before filing, ask the managing agent in writing whether the board is filing for the assessment year you want reviewed.

Class 1 and Class 2 condos

Nassau County sorts condominium units into two tax classes, and the class changes how the unit is valued:

• Class 1: residential condominium units in buildings not exceeding three stories that were not converted from rental or cooperative use. The County says these are usually valued by comparison with similar homes that have recently sold. An individual owner files on ARC’s form AR1, the same form used for houses.
• Class 2: condominium units in buildings of more than three stories, or converted from rental or cooperative use. The County values these, like co-ops, based on the property as a whole as if it were operated as a rental. Appeals for property other than one- to three-family homes and Class 1 condos use form AR2.

The class also affects limits on increases. The County says Class 1 assessments cannot rise more than 6% in a year or 20% over five years, apart from value added by construction or renovation, while increases for Class 2 are phased in through a five-year transitional assessment. If you think your unit is in the wrong class, that is a separate claim, filed on form AR3. See our guide to fixing record errors.

Evidence for a condo appeal

For a Class 1 unit, the most useful evidence is usually recent sales of comparable units: same building or complex where possible, similar size, floor, layout, and condition. Our comparable sales guide explains how to choose them. For a Class 2 building, the value rests on the building’s income potential, and the board, with its financial statements, is usually better placed to make that case than a single owner.

Start with the record

Look up your property to see how the County records your unit or building, and confirm its tax class on the County’s own record. Then ask the board what it files, and check the Department of Assessment’s exemptions information for anything you can apply for yourself. This page is general information, not legal or tax advice.