N.Y. Suffolk County Tax Act § 63
It shall be presumed that every tax levied and assessment made is valid and regular, and that all the steps and proceedings required by law were taken and had, until the contrary shall be made to appear. Any action or proceedings commenced by any person or persons to test the validity or regularity of any tax levied or assessment made shall be commenced within two years from the date of the receipt of the tax warrant by the town receiver of taxes. The invalidity or irregularity of any tax or assessment shall not be available as a defense to any action or proceeding commenced after the expiration of two years from the delivery of such warrant as aforesaid, or for the enforcement of any right or title, by virtue of any sale thereunder, unless an action or proceeding to test the validity or regularity of such tax or assessment shall have been commenced within the time hereinbefore limited for commencing the same, and shall be still pending, or such tax or assessment shall have been adjudged to be irregular and invalid
N.Y. Suffolk County Tax Act § 63