— Judgment of the Supreme Court, New York County (Mangan, J.), entered on March 3, 1982, which in granting respondent’s CPLR article 78 petition, directed appellant, the Commissioner of Finance, to refund to respondent the full amount of excess real property tax respondent had paid as a result of overvaluation as determined by a final judgment in a tax certiorari proceeding, without diminution, affirmed, without costs. In 1967, petitioner-respondent Ronald Associates No. 2 converted a building it owns in Manhattan from single-room occupancy to a multiple dwelling, thus qualifying for and receiving an exemption in the amount of $200,000 for a 12-year period under section J51-2.5 of the Administrative Code of the City of New York, implementing the enabling legislation, section 489 of the Real Property Tax Law. In 1980, respondent obtained a final judgment in a tax certiorari proceeding directing the commissioner to refund to respondent amounts of excess tax paid in the tax years 1976 through 1979 as a result of overvaluation of its property. In making that refund, the commissioner prorated the reduction in assessed valuation between the exempt and nonexempt portions of the total assessment. The effect of that proration was to reduce the actual dollar amount of the J51 exemption, and consequently to reduce the amount of the refund, by expressing the exemption as a proportion of assessed valuation rather than as a fixed amount. Special Term held correctly that the refund was to be computed without diminution by proration of the reduction in assessed valuation between exempt and nonexempt portions of the total assessment. Title J of chapter 51 affords an exemption in the amount of the “[ijncrease in value over that prior to conversion”. (NY Legis Ann, 1946, p 213; see Matter of 111 Fourth Ave. Assoc, v Finance Admin, of City ofN. Y., 101 Mise 2d 950, 952 [Kassal, J.].) The exemption afforded under title J of chapter 51 should be expressed as a fixed amount rather than as a proportion of *724assessed valuation, and is not subject to adjustment in a tax certiorari proceeding. The commissioner’s act of computing the exemption as a proportion was not authorized by statute or regulation and was contrary to the plain meaning of the Administrative Code and its enabling legislation. (See Matter of 600 West 183rd St. Corp. v Tishelman, 108 Mise 2d 780; Matter of Prince Wooster Corp. v Tax Comm, of City ofN. Y115 Mise 2d 100; but see Matter of Linden Hill No. 2 Coop. Corp. v Tishelman, 107 Mise 2d 799, affd for reasons stated at Special Term 87 AD 2d 577.) Concur — Kupferman, J. P., Sandler and Ross, JJ.