Real estate licensees have a duty to provide accurate information on their listings. Placing false, inaccurate or misleading information on a listing can result in incurring fines for violation of MLS Rules or the Code of Ethics (I assume the same or similar rules apply at all Boards), in addition to violations of DOS Rules and Regulations.
A licensee who provides incorrect taxes on a listing may not be protected by including such language as "the information on this listing is not guaranteed to be accurate". A licensee has a duty to use reasonable care in obtaining accurate information.
This means verifying the taxes before placing them on the listing by contacting the County and/or Town for the most up-to-date tax information.
Information obtained courtesy of the Long Island Multiple Listing Service