Appeal from a judgment of the Supreme Court (Kavanagh, J.), entered July 20, 2006 in Ulster County, which, in a proceeding pursuant to CPLR article 78, granted certain respondents’ motions to dismiss the petition and amended petition.

Petitioners each own property in the Town of Shandaken, Ulster County. On October 31, 2005, they commenced this CPLR article 78 proceeding against respondent Assessor of the Town of Shandaken contending that the methodology employed by her during tax year 2005 was unconstitutional. It is undisputed that the original petition named only the Assessor as a respondent and failed to name either respondent Ulster County or respondent Onteora Central School District as a party. By the time an amended petition adding these entities was filed, the statute of limitations had expired. At issue is a judgment of Supreme Court which dismissed this proceeding on two distinct grounds, namely, statute of limitations and failure to join necessary parties. Petitioners appeal.

Petitioners’ failure to timely join Ulster County and the School District, which are clearly necessary parties, mandated dismissal of the proceeding (see Matter of Haddad v City of Hudson, 6 AD3d 1018 [2004]; see also Matter of Resnick v Town of Canaan, 38 AD3d 949, 951 [2007]). While petitioners argue that they should be afforded the benefit of the relation back doctrine (see Buran v Coupal, 87 NY2d 173, 178 [1995]), we are unpersuaded. In short, their failure to name Ulster County and the School District in the first instance cannot be viewed as a “ ‘mistake by [petitioners] as to the identity of the proper parties’ ” (id., quoting Brock v Bua, 83 AD2d 61, 69 [1981]), but rather a mistake of law not encompassed by the doctrine (see e.g. Doe v HMO-CNY, 14 AD3d 102, 105-106 [2004]; Matter of Ferruggia v Zoning Bd. of Appeals of Town of Warwick, 5 AD3d 682, 683 [2004]; Matter of 27th St. Block Assn. v Dormitory Auth. of State of N.Y., 302 AD 2d 155, 165 [2002]; Matter of Brucha Mtge. Bankers Corp. v Commissioner of Labor of State of N.Y., 266 AD2d 211, 211-212 [1999], lv dismissed and denied 94 NY2d 893 [2000]; Somer & Wand v Rotondi, 251 AD2d 567,[*1100] 568-569 [1998]; State of New York v Gruzen Partnership, 239 AD2d 735, 736 [1997]). In other words, petitioners were clearly “fully aware” of the identity and existence of both Ulster County and the School District (Doe v HMO-CNY, 14 AD3d at 106 [internal quotation marks and citation omitted]; see Matter of Baker v Town of Roxbury, 220 AD2d 961, 963-964 [1995], lv denied 87 NY2d 807 [1996]) but, apparently,* failed to appreciate that these entities were legally required to be named in proceedings of this type (see Matter of Resnick v Town of Canaan, supra; Matter of Haddad v City of Hudson, supra), which is a mistake of law. Given our finding on this particular issue, we need not address whether there was a unity of interest between these parties for the purpose of the relation back doctrine or the propriety of that part of Supreme Court’s decision which dismissed the proceeding on statute of limitations grounds.

As a final matter, we are unpersuaded that this Court should remit the matter to Supreme Court for a determination as to whether this proceeding may proceed in the absence of these necessary parties pursuant to the discretionary factors outlined under CPLR 1001 (b) (see Matter of Romeo v New York State Dept. of Educ., 41 AD3d 1102 [2007]).

Cardona, P.J., Mugglin, Rose and Lahtinen, JJ., concur. Ordered that the judgment is affirmed, without costs.

Notably, the record contains no explanation by petitioners for their failure to timely name Ulster County and the School District as respondents (see Matter of Ogbunugafor v New York State Educ. Dept., 279 AD2d 738, 740 [2001], hi denied 96 NY2d 712 [2001]; Matter of Baker v Town of Roxbury, 220 AD2d at 963-964).