Order unanimously modified, on the law, and, as modified, affirmed, without costs, in accordance with the following memorandum: In this tax certiorari proceeding we hold that petitioner is entitled to discovery of assessment cards used by respondent in preparing tax assessments for petitioner's property for the tax years in question. Although an assessor's records are not discoverable to establish overassessment or the equalization rate ( Matter of City of Amsterdam v Board of Assessors, 91 A.D.2d 809; Blooming Grove Props. v Board of Assessors, 34 A.D.2d 953; Matter of Katz Buffalo Realty v Anderson, 25 A.D.2d 809), the documents are discoverable to establish that town officials are assessing petitioner in an unlawful manner ( Matter of Lessen v Stevens, 30 A.D.2d 740; see, also, Matter of Bauer v Board of Assessment Review, 114 Misc.2d 640, aff'd 91 A.D.2d 1097). Petitioner alleges that the town's assessments are based on values other than current market value and that its assessment is based on an agreement in contravention of the statute. Discovery should be permitted of any matter "`which is sufficiently related to the issues in litigation to make the effort to obtain it in preparation for trial reasonable'" ( Allen v Crowell-Collier Pub. Co., 21 N.Y.2d 403, 406-407, quoting 3A Weinstein-Korn-Miller, NY Civ Prac, par 3101:07, p. 31-13).