OPINION OF THE COURT
Memorandum.
The order of the Appellate Division should be affirmed, with costs.
The errors alleged by the County of Nassau on the motion to vacate the prior judgment do not constitute grounds for relief under CPLR 5015. Special Term abused *742its discretion in reopening its judgment to correct a perceived error of law that could have been raised on the prior appeals to the Appellate Division and to this court. A court’s inherent power to exercise control over its judgments is not plenary, and should be resorted to only to relieve a party “from judgments taken through [fraud,] ‘mistake, inadvertence, surprise or excusable neglect’ ” (Ladd v Stevenson, 112 NY 325, 332).
Furthermore, in reopening the judgment, Special Term modified the arbitrator’s award, and, in doing so, exceeded the narrow bounds within which courts are authorized to alter such awards. Clearly, the arbitrator’s award cannot be termed “so irrational as to require vacatur” (Matter of Garcia v Federal Ins. Co., 46 NY2d 1040, 1041). An award of interest under subdivision 1 of section 675 of the Insurance Law at the rate of 2%, compounded monthly, is warranted, if not mandated, by 11 NYCRR 65.15 (g) (1). Finally, the county’s contention that section 3-a of the General Municipal Law relieves municipalities from paying the statutory 2% interest rate on overdue no-fault payments is insufficient to justify modification of the award. The No-Fault Law’s legislative purpose of “guaranteeing prompt and full compensation for economic losses” (Montgomery v Daniels, 38 NY2d 41, 55) is furthered by the provision in section 675 of the Insurance Law for payment of 2% monthly interest on awards not paid within 30 days. The Legislature provided no exception to this interest rate for municipalities operating as self-insurers, and it is thus not irrational to assume that municipal self-insurers should be treated, under the No-Fault Law, in the same manner as any insurance company. (Cf. Matter of City of Syracuse v Utica Mut. Ins. Co., 61 NY2d 691.)
Chief Judge Cooke and Judges Jasen, Jones, Wachtler, Meyer and Kaye concur; Judge Simons taking no part.
On review of submissions pursuant to section 500.4 of the Rules of the Court of Appeals (22 NYCRR 500.4), order affirmed, with costs, in a memorandum.