OPINION

BORDEN, J.

The principal issue of this appeal is whether the defendant city of Norwalk acted constitutionally when, in 1994, it stayed the implementation of its decennial revaluation pursuant to No. 94-4, § 51, of the Public Acts, Spec. Sess., May, 1994 (Spec. Sess. P.A. 94-4, § 51). The plaintiff GTE Realty Corporation appeals from the judgment of the trial court in favor of the defendant. The plaintiff claims that the trial court improperly: (1) concluded that the defendant had validly postponed the revaluation for purposes of the grand lists of October 1, 1993 and 1994; (2) concluded that Spec. Sess. P.A. 94-4, § 51, is constitutional, both as enacted and as applied by the defendant to the plaintiff; and (3) declined to consider the plaintiff's challenge to the defendant's subsequent postponements of the implementation of the revaluation, with regard to the 1995 and 1996 grand lists, which took place during the pendency of this case. Addressing the merits of those subsequent actions by the defendant, the plaintiff also claims that they were invalid. We conclude that: (1) the defendant's actions in postponing the revaluation for purposes of the 1993 and 1994 grand lists was valid; (2) there is no constitutional infirmity in Spec. Sess. P.A. 94-4, § 51, either as enacted or as implemented by the defendant; (3) under the circumstances of this case, the trial court should have adjudicated the plaintiff's claims regarding the 1995 and 1996 grand lists; and (4) under No. 97-254, § 1(b)(1) of the 1997 Public Acts ( P.A. 97-254), the defendant may postpone its revaluation until 1999. Accordingly, we affirm the judgment in part and reverse the judgment in part.

In its intervening complaint, the plaintiff challenged the defendant's action of staying the implementation of the defendant's October 1, 1993 decennial revaluation, which had the affect of retaining the real property valuations of October 1, 1983, for the grand lists of 1993 and 1994. That action had been taken in 1994, pursuant to Spec. Sess. P.A. 94-4, § 51, later codified as General Statutes (Rev. to 1995) § 12-62h, which the plaintiff claimed was unconstitutional. The plaintiff's complaint contained two counts. In the first count, the plaintiff appealed from its tax assessment pursuant to General Statutes § 12-119, claiming that its tax assessment was illegal because of, inter alia, the unconstitutionality of Spec. Sess. P.A. 94-4, § 51. In the second count, the plaintiff sought a declaratory judgment that Spec. Sess. P.A. 94-4, § 51, was unconstitutional.

The plaintiff's complaint purported to be limited to a challenge to the defendant's 1994 staying of the revaluation, affecting the grand lists of 1993 and 1994, and the plaintiff did not submit an amended complaint formally expanding its claims beyond those grand lists. Nonetheless, the record discloses that the parties subsequently also submitted to the trial court the question of whether the defendant acted legally in further staying the revaluation, such that it was not implemented for the grand lists of October 1, 1995, and October 1, 1996, pursuant to No. 95-283, § 8, of the 1995 Public Acts ( P.A. 95-283), and No. 96-218, §§ 1 and 3, of the 1996 Public Acts ( P.A. 96-218).

The following facts are undisputed. Since 1980, the plaintiff has owned real property in Norwalk, located at 32 Weed Avenue, where it operates a management and development center. In 1993, the defendant conducted a decennial revaluation of all real property located in the city for purposes of establishing a new grand list as of October 1, 1993 (1993 revaluation), pursuant to General Statutes (Rev. to 1993) § 12-62 (a). The previous revaluation had been in 1983, based on real property values as of that time (1983 revaluation). On the basis of the 1993 revaluation, the defendant established a proposed 1993 grand list. The plaintiff was notified that, as of October 1, 1993, its assessment would be $22,750,420. The plaintiff appealed its 1993 assessment to the board of tax review.

On January 24, 1994, however, the director of finance reported to the board of estimate and finance that, after revaluation, revenues from commercial and industrial properties would decline from 26.9 percent to 25.6 percent of the grand list, revenues from condominiums would decline from 10.3 percent to 8.9 percent of the grand list, and revenues from noncondominium residences would increase from 45.6 percent to 53.5 percent of the grand list. On March 8, 1994, at the meeting of the common council, the mayor was granted authorization to seek permission from the state to defer implementation of the revaluation for no more than three years. Pursuant to General Statutes (Rev. to 1993) § 12-117, however, the state office of policy and management may grant a municipality an extension of no more than two months to complete the process of hearing taxpayers' appeals regarding a revaluation. On March 16, 1994, the board of tax review and the mayor wrote to the office of policy and management seeking a one year extension. The office of policy and management, however, granted only a two month extension, until May 31, 1994, as permitted by the statute.

On April 22, 1994, the board of estimate and taxation established a final budget and mill rate based, not on the 1993 revaluation, but on the 1983 revaluation. This had the effect on real property owners, including the plaintiff, of carrying forward the 1992 grand list, based on the values of real property as of 1983, rather than 1993.

Under the 1983 revaluation, the plaintiff's assessment was $24,058,826, resulting in a tax bill of $1,119,938.35. Under the defendant's proposed 1993 revaluation, which has not been implemented, the plaintiff's assessment would have been $22,750,420 and, under the defendant's proposed mill rate, the plaintiff's tax bill would have been $687,290.19. As a result of the deferment of the 1993 revaluation, therefore, the plaintiff's tax bill on the 1993 grand list was increased by $432,648.16, or 39 percent, over what it would have been had the 1993 revaluation been implemented.

On or about June 1, 1994, while the plaintiff's appeal to the board of tax review was pending, the defendant issued tax bills, based on the 1983 revaluation, accompanied by a letter from the mayor stating that the implementation of the 1993 revaluation had been postponed. Prior to the issuance of these tax bills, the board of tax review did not hold hearings on appeals by taxpayers potentially aggrieved by the 1993 assessment.

On June 9, 1994, Spec. Sess. P.A. 94-4 became effective. See Spec. Sess. P.A. 94-4, § 85. Section 51 of Spec. Sess. P.A. 94-4, in general terms, permits the legislative body of a municipality to stay the implementation of a decennial revaluation for up to two years. On June 28, 1994, the common council suspended its rules and, purporting to act pursuant to Spec. Sess. P.A. 94-4, passed a resolution, not listed on its agenda, authorizing the stay of the implementation of the 1993 revaluation. In the discussion of this resolution, the corporation counsel described this action as a ratification of the common council's prior decision to request a stay of the 1993 revaluation. Thereafter, on December 27, 1994, the common council also voted to stay the implementation of the 1993 revaluation until July 1, 1996. In addition, during the pendency of this case, the defendant has enacted further postponements of the revaluation, which have had the effect of retaining the 1983 real property valuations for the grand lists of 1995 and 1996.

The trial court rejected the plaintiff's various statutory and constitutional challenges to the defendant's actions in staying the 1993 revaluation. The court declined to consider, however, the plaintiff's challenge to the defendant's action in further postponing the revaluation for the 1995 and 1996 grand lists, which steps the defendant purportedly had taken pursuant to P.A. 95-283, § 8, and P.A. 96-218, §§ 1 and 3. Accordingly, the court rendered judgment for the defendant with respect to the stay of the 1993 revaluation, affecting only Spec. Sess. P.A. 94-4, § 51, and the 1993 and 1994 grand lists. This appeal followed.

I

The plaintiff first claims that the defendant did not validly postpone the revaluation for purposes of the 1993 and 1994 grand lists. The plaintiff relies on the conclusion of the trial court that the defendant's action on June 28, 1994, purporting to ratify its prior decision to postpone the 1993 revaluation, could not be a valid ratification because, prior to Spec. Sess. P.A. 94-4, the defendant had no such power of postponement. The plaintiff contends, therefore, that the defendant's action in postponing the 1993 revaluation was invalid. We disagree.

It is true that the trial court concluded that, prior to the enactment of Spec. Sess. P.A. 94-4, the defendant was without any power to postpone the 1993 revaluation and that, therefore, any attempt to ratify what was in effect an ultra vires act was ineffective. It does not follow from that conclusion, however, that the defendant's action on June 28, 1994, was also ineffective to postpone the 1993 revaluation pursuant to Spec. Sess. P.A. 94-4, § 51.

As the trial court also concluded, correctly, Spec. Sess. P.A. 94-4, § 51, by its terms had retrospective effect, and the defendant's June 28, 1994 resolution, which was specifically authorized by and passed pursuant to that act, validly postponed the 1993 revaluation. Thus, although the defendant's June 28, 1994 resolution could not validly have had the effect of ratifying the defendant's action in postponing the revaluation prior to the enactment of Spec. Sess. P.A. 94-4, once that act became effective on June 9, 1994, the same resolution, passed pursuant to Spec. Sess. P.A. 94-4, did have the legal effect of postponing the revaluation.

Section 51 of Spec. Sess. P.A. 94-4; see footnote 4 of this opinion; provided in pertinent part: "Notwithstanding any provision of title 12 of the general statutes, the local legislative body of a municipality may, at its option, stay the implementation of such municipality's revaluation in order to implement the recommendations of the Property Tax Reform Commission enacted during the 1995 session of the general assembly. The local legislative body of a municipality may stay such implementation for a period or periods not to exceed in the aggregate two years. . . . Any municipality required to implement revaluation for the assessment year commencing October 1, 1993, which has not as of February 15, 1994, adopted mill rates for taxes due July 1, 1994, may use such municipality's most recently completed grand list prior to revaluation . . . . Any municipality required to implement revaluation for the year commencing October 1, 1994, which has not as of February 15, 1995, adopted a mill rate for taxes due July 1, 1995, may use such municipality's most recently completed grand list prior to revaluation . . . ." (Emphasis added.)

Legislation is generally presumed to operate prospectively, unless the legislature makes clear its intent that it operate retrospectively. Bayusik v. Nationwide Mutual Ins. Co., 233 Conn. 474, 483-84, 659 A.2d 1188 (1995). The text of Spec. Sess. P.A. 94-4, § 51, itself makes clear the legislative intent that it apply retrospectively, because it makes its application conditional on events that preceded its effective date of June 9, 1994, namely, whether a municipality had adopted mill rates as of the previous February 15. It is equally clear that the defendant met all of these conditions because it had not adopted a mill rate as of February 15, 1994, and further, it did not adopt a mill rate as of February 15, 1995. Therefore, when the common council, on June 28, 1994, voted to stay the implementation of the revaluation with respect to the 1993 and 1994 grand lists, it acted legally pursuant to Spec. Sess. P.A. 94-4, § 51.

II

The plaintiff next claims that Spec. Sess. P.A. 94-4, § 51, is unconstitutional under the federal and state constitutions because: (1) it "is void of standards" and, therefore, involves an impermissible delegation of legislative power in violation of due process of law; (2) it is void for vagueness in violation of due process of law; and (3) it deprives the plaintiff of the equal protection of the laws. None of these claims is persuasive.

Legislation is presumed to be constitutional, and a litigant challenging its validity has the heavy burden to establish its unconstitutionality beyond a reasonable doubt. State v. Wilchinski, 242 Conn. 211, 217-18, 700 A.2d 1 (1997). The plaintiff has not met this burden.

A

The plaintiff's claim that Spec. Sess. P.A. 94-4, § 51, involves an impermissible delegation of legislative power founders on this court's holding in Bottone v. Westport, 209 Conn. 652, 553 A.2d 576 (1989). The limitation that the legislature may not delegate its power without establishing primary standards or an intelligible principle for carrying out that power emanates from the constitutional doctrine of the separation of powers. Id., 660. "The separation of powers doctrine, however, does not pertain to delegations from the state legislature to a municipality." Id., 664. "[T]hus, a nondelegation rule grounded in that constitutional limitation is inapposite . . . ." Id.

B

The plaintiff's claim that Spec. Sess. P.A. 94-4, § 51, is void for vagueness and, therefore, violative of due process of law, is also unpersuasive. When a legislature delegates its power to a municipality, "none of the limitations imposed on administrative or executive agencies applies. Thus, the delegation may be of the most general nature and it will not be invalid for failure to create an adequate standard." (Internal quotation marks omitted.) Bottone v. Westport, supra, 209 Conn. 668-69. Under the due process vagueness rubric, "the proper standard for a delegation of power from the state legislature to a municipality, based on both constitutional analysis and the reality of state and local governmental relations, is that such a delegation should be judged by whether it provides reasonable notice of what conduct may be authorized or prohibited under its provisions." Id., 675.

Judged by this standard, Spec. Sess. P.A. 94-4, § 51, passes constitutional muster. The act authorized the defendant, at the option of its common council, to stay the implementation of its decennial revaluation, in order to implement the recommendations of the property tax reform commission that the legislature expected to be enacted in the 1995 session of the General Assembly. It conditioned that authority on the determination of whether, as of February 15, 1994, the defendant had adopted a mill rate. There is nothing unconstitutionally vague about these directions to the defendant regarding what conduct was authorized.

C

The plaintiff's final constitutional challenge is to the defendant's application to the plaintiff of Spec. Sess. P.A. 94-4, § 51. The plaintiff claims that, in staying the implementation of the revaluation pursuant to Spec. Sess. P.A. 94-4, the defendant deprived the plaintiff of the equal protection of the laws because the defendant "deliberately and intentionally acted for the benefit of one classification of taxpayers," namely, single-family residential homeowners, "to the detriment of others," namely, commercial property owners such as the plaintiff. In this regard, the plaintiff relies heavily on the trial court's finding that the common council "voted to stay its decennial revaluation of real property because of a shift in the tax burden to single-family homeowners from nonsingle-family property owners which would result." We reject the plaintiff's claim.

The parties agree, as do we, that the constitutionality of the defendant's action taken pursuant to Spec. Sess. P.A. 94-4, § 51, must be gauged under the rational basis test. "In the context of an equal protection challenge to social and economic legislation that does not infringe upon a fundamental right or affect a suspect group, the classification drawn by the statute will not violate the equal protection clause if it is rationally related to a legitimate public interest. Nordlinger v. Hahn, 505 U.S. 1, 8, 112 S.Ct. 2326, 120 L.Ed.2d 1 (1992); Cleburne v. Cleburne Living Center, Inc., 473 U.S. 432, 439-41, 105 S.Ct. 3249, 87 L.Ed.2d 313 (1985). . . .

"The United States Supreme Court has recently summarized the rational basis test as applied to social and economic legislation that does not infringe upon a fundamental right or affect a suspect group. Nordlinger v. Hahn, supra, [505 U.S. 11-12]. In general, the Equal Protection Clause is satisfied so long as there is a plausible policy reason for the classification, see United States Railroad Retirement Board v. Fritz, 449 U.S. 166, 174, 179 [ 101 S.Ct. 453, 66 L.Ed.2d 368 (1980), reh. denied, 450 U.S. 960, 101 S.Ct. 1421, 67 L.Ed.2d 385 (1981)], the legislative facts on which the classification is apparently based rationally may have been considered to be true by the government decisionmaker, see Minnesota v. Clover Leaf Creamery Co., 449 U.S. 456, 464 [ 101 S.Ct. 715, 66 L.Ed.2d 659, reh. denied, 450 U.S. 1027, 101 S.Ct. 1735, 68 L.Ed.2d 222] (1981), and the relationship of the classification to its goal is not so attenuated as to render the distinction arbitrary or irrational, see Cleburne v. Cleburne Living Center, Inc., [supra, 473 U.S. 446]. Nordlinger v. Hahn, supra, [11].

"Moreover . . . [i]n the context of tax legislation, a party challenging a statute on equal protection grounds has an even greater burden than equal protection challenges to other social and economic statutes that do not infringe upon a fundamental right or affect a suspect group. In tax matters, more so than in other fields, legislatures possess considerable liberty in classification. Gallacher v. Commissioner of Revenue Services, 221 Conn. 166, 181, 602 A.2d 996 (1992); see also Nordlinger v. Hahn, supra, [505 U.S. 11-12] (upholding California's property tax scheme under Proposition 13 against equal protection challenge); Regan v. Taxation with Representation of Washington, 461 U.S. 540, 547, 103 S.Ct. 1997, 76 L.Ed.2d 129 (1983) (denial of tax exemption to nonprofit lobbying organizations, but with an exception for veterans groups, does not violate equal protection).

"Therefore, the presumption of constitutionality can be overcome only by the most explicit demonstration that the classification is a hostile and oppressive discrimination against particular persons and classes. The burden is on the one attacking the legislative arrangement to negative every conceivable basis which might support it. . . . Miller v. Heffernan, 173 Conn. 506, 509-10, 378 A.2d 572 (1977), appeal dismissed, 434 U.S. 1057, 98 S.Ct. 1226, 55 L.Ed.2d 758 (1978)." (Emphasis in original; internal quotation marks omitted.) Johnson v. Meehan, 225 Conn. 528, 535-37, 626 A.2d 244 (1993). Furthermore, when a court determines whether a legislative classification is a hostile and oppressive discrimination against a particular class, the challenger must establish that the legislature "selected or reaffirmed a particular course of action at least in part `because of,' not merely `in spite of,' its adverse effects upon an identifiable group." Personnel Administrator of Massachusetts v. Feeney, 442 U.S. 256, 279, 99 S.Ct. 2282, 60 L.Ed.2d 870 (1979).

Under this well established equal protection jurisprudence, the plaintiff's challenge to the defendant's action in staying the implementation of the revaluation fails. The most obvious rational basis for the defendant's action was to implement, in an orderly manner, the changes to the existing property taxation system anticipated to be enacted in the next legislative session as a result of the recommendations of the property tax reform commission. See United Illuminating Co. v. New Haven, 179 Conn. 627, 648, 427 A.2d 830, appeal dismissed, 449 U.S. 801, 101 S.Ct. 45, 66 L.Ed.2d 5 (1980) (tax phase-in statute and local ordinance implementing it did not violate equal protection clause notwithstanding that phase-in act resulted in continued temporary inequities that mandatory periodic revaluation and uniform assessment rate were designed to ameliorate). That this "purpose may conceivably . . . have been the purpose and policy of the relevant governmental decisionmaker"; (internal quotation marks omitted) Nordlinger v. Hahn, supra, 505 U.S. 15; is demonstrated by the fact that it was the stated purpose of Spec. Sess. P.A. 94-4, § 51, pursuant to which the defendant acted.

The plaintiff's reliance on the trial court's finding, namely, that the defendant stayed its decennial revaluation because of a shift in the tax burden from single-family homeowners to nonsingle-family homeowners that would result, is misplaced. First, the plaintiff ignores the trial court's concomitant finding that the defendant "chose this course, however, not to burden commercial property owners but to alleviate the burden on single-family homeowners, that is, `in spite of,' not `because of' the burden which would be assumed by nonsingle-family property owners." Thus, the trial court recognized the economic reality that when a legislative body makes a taxing decision it almost inevitably will be involved in shifting tax burdens from one group to another. The defendant's motivation did not offend the equal protection clause, however, because it was made in spite of, not because of, the burden it placed on commercial property owners. Personnel Administrator of Massachusetts v. Feeney, supra, 442 U.S. 279. Put another way, the plaintiff has failed to make "`the most explicit demonstration that the classification [was] a hostile and oppressive discrimination against particular persons and classes.'" Johnson v. Meehan, supra, 225 Conn. 537.

Second, and more important, the plaintiff's reliance on the political motivations of the defendant's officials in staying the decennial revaluation is simply not in accord with current United States Supreme Court rational basis analysis, which is binding on this court in applying federal constitutional principles. The Supreme Court has stated the test under equal protection principles when the challenged legislation does not involve fundamental rights or suspect categories as follows: "Where, as here, there are plausible reasons for [the legislative body's] action, our inquiry is at an end. It is, of course, constitutionally irrelevant whether this reasoning in fact underlay the legislative decision . . . ." (Citation omitted; internal quotation marks omitted.) United States Railroad Retirement Board v. Fritz, supra, 449 U.S. 179. We have consistently followed this course in applying rational basis analysis to equal protection claims. See, e.g., Johnson v. Meehan, supra, 225 Conn. 539; United Illuminating Co. v. New Haven, supra, 179 Conn. 639.

Third, even if we were to assume that the defendant acted in order to protect single-family homeowners from increased taxes, that would not necessarily be unconstitutional. The government may, without violating the equal protection clause, impose different tax burdens on different classes of property. See, e.g., Allegheny Pittsburgh Coal Co. v. County Commission of Webster County, West Virginia, 488 U.S. 336, 344, 109 S.Ct. 633, 102 L.Ed.2d 688 (1989); United Illuminating Co. v. New Haven, supra, 179 Conn. 647. Furthermore, in United Illuminating Co. v. New Haven, supra, 647, we specifically indicated that the goal of protecting residential property owners from a sudden increase in taxation due to revaluation was a legitimate basis for legislation that authorized delay in the implementation of a new taxation scheme, despite the fact that the delay temporarily thrust an unequal burden of taxation on other categories of real property owners.

III

We next consider the plaintiff's claim that the trial court improperly concluded that it lacked subject matter jurisdiction to adjudicate the plaintiff's contentions that further postponements of the revaluation by the defendant, pursuant to P.A. 95-283, § 8, and P.A. 96-218, §§ 1 and 3, were invalid. The plaintiff also argues the merits of those contentions. The defendant responds that: (1) the trial court was correct in its determination that it lacked jurisdiction; (2) if the trial court was incorrect, the plaintiff's contentions lack merit; and (3) in any event, subsequent legislation, namely, P.A. 97-254, § 1(b), renders any challenge to the defendant's actions moot by authorizing the defendant to postpone its revaluation until 1999.

We conclude that the court did have subject matter jurisdiction to adjudicate the plaintiff's claims regarding the two additional postponements, as well as the validity of P.A. 95-283, § 8, and P.A. 96-218, §§ 1 and 3. Ordinarily that conclusion would lead us to remand the case to the trial court to adjudicate those claims in the first instance. In this case, however, we have decided to address those claims because they do not require further fact-finding, they are adequately briefed here, and both the plaintiff and the defendant need to know now what their respective tax obligations and rights are. We conclude that P.A. 97-254 lays to rest any question about the defendant's actions in postponing the revaluation beyond 1994, and that the defendant need not conduct a revaluation until 1999.

The following additional facts and procedural history are relevant to the remainder of our analysis. After the completion of the evidence in this case but before the trial court issued its memorandum of decision on March 10, 1997, the parties, following a status conference with the trial court on October 16, 1996, in early November, 1996, entered into a written supplemental stipulation to the following facts. On December 12, 1995, the common council voted, pursuant to P.A. 95-283, § 8, to postpone for an additional one year period the implementation of the defendant's revaluation for the grand list of October 1, 1995. Accordingly, the defendant adopted its annual budget for the 1996-97 fiscal year based on the October 1, 1995 grand list, using the assessment values established in 1983, and the plaintiff was presented with a tax bill for the October 1, 1995 grand list of $1,122,825. The parties further stipulated that, on August 13, 1996, the common council voted, pursuant to P.A. 96-218, to postpone for an additional one year period the implementation of the revaluation for the grand list of October 1, 1996. In addition, although it was not formally part of the stipulation, it is undisputed that this action of the defendant in 1996 had the effect of continuing, for an additional, fourth fiscal year, the use of the 1983 assessment values.

Furthermore, the parties filed supplemental posttrial briefs addressing the issues of the applicability of P.A. 95-283 and P.A. 96-218 to the 1995 and 1996 grand lists, as well as the issues regarding the constitutionality of those acts, and the defendant filed additional exhibits in connection with those issues. The plaintiff's claims in these supplemental proceedings mirrored its claims regarding the actions of the defendant in 1994, and the effect thereon of Spec. Sess. P.A. 94-4. More specifically, the plaintiff claimed that: (1) nothing in either P.A. 95-283 or P.A. 96-218 authorized the defendant to continue to postpone the revaluation; and (2) application of those acts would deprive the plaintiff of equal protection of the laws.

The trial court, however, specifically declined to address the plaintiff's claims regarding P.A. 95-283 and P.A. 96-218 and the two grand lists in issue, for two reasons. First, the plaintiff had not amended its complaint to include the challenges to the 1995 and 1996 grand lists and P.A. 95-283 and P.A. 96-218. Second, the plaintiff was seeking a declaratory judgment as well as relief under § 12-119. Thus, the court reasoned, although notice had been given pursuant to Practice Book § 390(d), now Practice Book (1998 Rev.) § 17-55 (4), to all interested parties, namely, all Norwalk taxpayers and the chief executive officers of the other 168 municipalities, with respect to the plaintiff's challenges to the 1994 grand list and Spec. Sess. P.A. 94-4, no such notice had been given with respect to its challenges to the 1995 and 1996 grand lists and P.A. 95-283 and P.A. 96-218. The defendant, although it did not object to the trial court's consideration of the 1995 and 1996 grand lists and P.A. 95-283 and P.A. 96-218, and instead argued in that court against the plaintiff's claims on their merits, adopts on appeal the trial court's reasons for declining to address the claims at issue. We disagree with both reasons.

With respect to the lack of an amendment of the complaint, it is true that ordinarily a court may not grant relief on the basis of an unpleaded claim. Willametz v. Guida-Seibert Dairy Co., 157 Conn. 295, 302, 254 A.2d 473 (1968) ("`[a] plaintiff may not allege one cause of action and recover upon another'"); Malone v. Steinberg, 138 Conn. 718, 721, 89 A.2d 213 (1952) (same). That does not necessarily mean, however, that the absence of a particular claim from the pleadings automatically precludes a trial court from addressing the claim, because a court may, despite pleading deficiencies, decide a case on the basis on which it was actually litigated and may, in such an instance, permit the amendment of a complaint, even after the trial, to conform to that actuality. See, e.g., Saphir v. Neustadt, 177 Conn. 191, 206, 413 A.2d 843 (1979). Indeed, we have recognized that, even in the absence of such an amendment, where the trial court had in fact addressed a technically unpleaded claim that was actually litigated by the parties, it was improper for the Appellate Court to reverse the trial court's judgment for lack of such an amendment. See, e.g., Tedesco v. Stamford, 215 Conn. 450, 458-63, 576 A.2d 1273 (1990), remanded, 24 Conn. App. 377, 588 A.2d 656 (1991), rev'd, 222 Conn. 233, 610 A.2d 574 (1992). Whether to grant such a posttrial amendment is within the discretion of the trial court. McLaughlin Ford, Inc. v. Ford Motor Co., 192 Conn. 558, 564, 473 A.2d 1185 (1984) ("`[t]he trial court has wide discretion in granting or denying amendments before, during, or after trial'"); Lawson v. Godfried, 181 Conn. 214, 216, 435 A.2d 15 (1980) (same).

In the present case, the only appropriate procedure for the trial court to employ would have been to decide the issues despite the lack of such an amendment, and to permit the complaint to be amended posttrial so as to conform to the parties' proof. The parties, after a status conference with the court, had entered into a factual stipulation reflecting the issues raised under P.A. 95-283 and P.A. 96-218, had entered exhibits in connection therewith, and had extensively briefed the issues presented. No one would have been surprised or prejudiced by consideration of the issues. Under these circumstances, it was an abuse of discretion for the trial court to decline to adjudicate those issues based on a lack of a formal amendment of the complaint.

The second reason given by the trial court, namely, the lack of notice to interested parties with regard to the 1995 and 1996 grand lists and P.A. 95-283 and P.A. 96-218, poses different considerations. We conclude, nonetheless, that this reason was insufficient to preclude the trial court's consideration of those issues because, apart from the plaintiff's claim for declaratory relief, the plaintiff's nondeclaratory claim for relief under § 12-119 was before the court.

The trial court concluded that it lacked subject matter jurisdiction to consider the plaintiff's request for a declaratory judgment regarding P.A. 95-283 and P.A. 96-218 because, although notice had been given to all Norwalk taxpayers and to the chief executive officers of the other 168 Connecticut municipalities regarding the plaintiff's challenges to Spec. Sess. P.A. 94-4 — who presumably were the "interested parties" to whom notice was required to be given pursuant to Practice Book § 390(d) — no such notice had been given to them regarding the subsequent challenges to P.A. 95-283 and P.A. 96-218. This conclusion was based on the principle, under our declaratory judgment jurisprudence, that the failure to give notice to interested parties under Practice Book § 390(d) deprives the court of jurisdiction to render a declaratory judgment. See, e.g., Russo v. Watertown, 184 Conn. 30, 33-35, 441 A.2d 56 (1981); compare Serrani v. Board of Ethics, 225 Conn. 305, 309 n. 5, 622 A.2d 1009 (1993) (initial failure to give notice only deprives court of jurisdiction to render judgment; such failure may be remedied by subsequent notice); Connecticut Ins. Guaranty Assn. v. Raymark Corp., 215 Conn. 224, 230, 575 A.2d 693 (1990) (same).

This principle is not dispositive of the claims concerning the 1995 and 1996 grand lists and P.A. 95-283 and P.A. 96-218, however, because in connection with its claim for declaratory relief, the plaintiff concomitantly sought substantive relief as a taxpayer under § 12-119, through which claim for relief all of its claims regarding the 1995 and 1996 grand lists and those acts were validly presented to the trial court. Section 12-119 applies to two types of taxpayer challenges to a town's real property assessment or revaluation. The first, not involved here, applies to "the absolute nontaxability of the property in the municipality where situated . . . ." (Internal quotation marks omitted.) Wilson v. Kelley, 224 Conn. 110, 118-19, 617 A.2d 433 (1992). The second, which the plaintiff invoked here, "consists of claims that assessments are (a) manifestly excessive and (b) . . . could not have been arrived at except by disregarding the provisions of the statutes for determining the valuation of the property." (Internal quotation marks omitted.) Id., 119. Under this second category of claim, the plaintiff must establish, in addition to a manifestly excessive valuation, that the assessment is illegal. Id. The substantive claims included in the plaintiff's declaratory judgment count — the claims regarding the 1995 and 1996 grand lists, as affecting its property, and regarding the inapplicability and invalidity of P.A. 95-283 and P.A. 96-218 with respect to those two grand lists — were therefore properly raised in the plaintiff's complaint under the § 12-119 count. The concomitant request for declaratory relief did not diminish the propriety of raising those claims in the nondeclaratory portion of its complaint. Indeed, we have made clear that "a declaratory judgment action must rest on some cause of action that would be cognizable in a nondeclaratory suit." Wilson v. Kelley, supra, 116. Thus, even if we were to assume, without deciding, that the plaintiff was required by Practice Book § 390(d) to give further notice of its additional claims, any lack of proper notice under that section with respect to the declaratory judgment count did not deprive the court of jurisdiction to consider those claims in the context of the plaintiff's nondeclaratory count. Because the plaintiff was entitled to, and did, raise those claims in its complaint under § 12-119, it was improper for the court to decline to consider them.

We acknowledge that in Cioffoletti v. Planning Zoning Commission, 209 Conn. 544, 563, 552 A.2d 796 (1989), which involved a challenge to the validity of a decision of the Ridgefield planning and zoning commission and the regulation upon which the decision was based, we stated that certain general challenges to the legality of legislation in which many persons may have an interest may be brought only through a declaratory judgment action, in order to ensure that notice be provided to all interested parties. Id. ("[t]he final constitutional issue, relating to the adequacy of the regulations in setting forth standards for a decision upon an application, constitutes the kind of general attack upon land use regulations that we have indicated should be the subject of a declaratory judgment action rather than an appeal from the denial of an application submitted pursuant to those regulations"); see also Bombero v. Planning Zoning Commission, 218 Conn. 737, 745, 591 A.2d 390 (1991) (stating that Cioffoletti rule applied where "the plaintiff mounts a general attack on the legislative enactment of a regulation, primarily based on constitutional vagueness grounds, and combines therewith nonconstitutional grounds for the regulation's invalidity"). If the Cioffoletti rule were applied in the present case, it effectively would preclude § 12-119 as a vehicle for the plaintiff's claims regarding the validity of the 1995 and 1996 grand lists and P.A. 95-283 and P.A. 96-218.

In our view, however, that rule, which limits the ability of parties to pursue statutory avenues of appeal in regard to municipal or agency legislation, is ill-conceived. First, it has little support in our case law. None of the three cases cited in Cioffoletti — National Transportation Co. v. Toquet, 123 Conn. 468, 478, 196 A. 344 (1937); Florentine v. Darien, 142 Conn. 415, 428-30, 115 A.2d 328 (1955); and Russo v. Watertown, supra, 184 Conn. 33-35 — lends support to the rule and, in fact, Toquet directly undermines it. In Toquet, which involved both a declaratory judgment action and a substantive appeal challenging the validity of a municipal zoning regulation, we held that, although the declaratory judgment action could not be maintained because of a failure to provide the requisite notice to the other interested property owners, the plaintiff could pursue its claims through its substantive appeal. National Transportation Co. v. Toquet, supra, 481-86. Florentine merely articulated the complementary principles that: (1) a litigant may not, in the course of a statutory based appeal concerning the actions of a municipality or an agency, challenge the validity of the statute providing the basis for the appeal; but (2) an independent declaratory judgment action challenging that statute could subsequently be brought. Florentine v. Darien, supra, 428-30. Florentine does not, however, suggest that only a declaratory judgment action may be maintained when a party to otherwise proper litigation challenges the validity of legislation that is being applied to the party. Similarly, Russo contained no suggestion of this requirement. Rather, in that case, the plaintiff's challenge to the municipal legislation at issue was a declaratory judgment action. This court's conclusion that the claim could not be maintained because of the plaintiff's failure to provide notice to all interested parties constituted nothing more than an application of the declaratory judgment notice rule. Russo v. Watertown, supra, 33-35.

In addition, as we acknowledged in Bombero, many of our decisions have allowed plaintiffs to pursue challenges to the validity of municipal or agency regulations or other legislation through actions other than declaratory judgment actions, including through statutory appeals. Bombero v. Planning Zoning Commission, supra, 218 Conn. 744 (citing, as examples, Carofano v. Bridgeport, 196 Conn. 623, 495 A.2d 1011; New Milford v. SCA Services of Connecticut, Inc., 174 Conn. 146, 384 A.2d 337; Sonn v. Planning Commission, 172 Conn. 156, 374 A.2d 159; Zenga v. Zebrowski, 170 Conn. 55, 364 A.2d 213); see also Rosnick v. Zoning Commission, 172 Conn. 306, 307-308, 374 A.2d 245 (1977) (after concluding that action challenging zoning regulation could not be maintained as declaratory judgment action because of failure to provide proper notice to all interested parties, court treated complaint as appeal from decision of zoning commission). As we acknowledged in Bombero v. Planning Zoning Commission, supra, 744, these decisions are difficult to reconcile with the Cioffoletti rule. Especially in conjunction with our cases indicating that a declaratory judgment action is inappropriate when a plaintiff has available another speedy remedy that would be as effective, convenient, appropriate and complete as a declaratory judgment action; see Practice Book § 390(c), now Practice Book (1998 Rev.) § 17-55 (3); see also, e.g., England v. Coventry, 183 Conn. 362, 365, 439 A.2d 372 (1981); these inconsistencies have left the trial courts and potential litigants in confusion regarding the proper form of action to pursue.

Finally, in our view, the concern for third party interests in the challenged legislation, the protection of which constitutes the rationale for the Cioffoletti rule, is outweighed by the importance of honoring the legislature's grant of statutory avenues of appeal with regard to municipal or agency legislation. As we stated in Toquet, "[t]here are many instances in which a party is entitled to relief at law, even though the proceedings he brings may result in the establishment of a rule which will directly affect the interests of others not parties to the action." National Transportation Co. v. Toquet, supra, 123 Conn. 481. Indeed, every decision that substantively affects the shape of the law inevitably impacts upon the interests of third persons. In general, however, notice to such persons is not required, not only because such a requirement would be unduly burdensome, but also because their interests are adequately represented by a defendant and by a plaintiff with proper standing. In our view, in challenges to the validity of municipal or agency legislation, the interests of the municipality or agency in upholding its legislation provide sufficient protection to the interests of third parties in that legislation and, therefore, it is not necessary to require that such challenges be brought as declaratory judgment actions. See id., 482 ("at least in so far as relief to the plaintiff is concerned, the municipality, made a party to the action, represents the residents and property owners within its boundaries"). Therefore, we abandon the Cioffoletti rule requiring that general attacks on the validity of legislation be brought in the form of declaratory judgment actions instead of substantive appeals.

We turn, therefore, to the merits of the plaintiff's claims regarding the 1995 and 1996 grand lists. The plaintiff contends that the postponement of the revaluation by the defendant on those grand lists "was not statutorily permitted or constitutionally valid." The plaintiff's constitutional claims are the same as those raised with respect to the 1994 grand list, and are without merit for the same reasons we gave regarding that grand list.

With respect to the plaintiff's statutory claims, the plaintiff first argues that if Spec. Sess. P.A. 94-4, § 51, was invalidly applied to it, "Norwalk cannot rely on either of the subsequent statutory amendments in 1995 and 1996 to further postpone revaluation." We already have rejected, however, the plaintiff's challenges to Spec. Sess. P.A. 94-4 and the defendant's conduct thereunder.

The plaintiff next argues that P.A. 95-283, § 8, and P.A. 96-218, §§ 1 and 3, provided no valid statutory authority for the postponements of the revaluation on the 1995 and 1996 grand lists. We need not address the effect of P.A. 96-218, however, because we agree with the defendant that P.A. 97-254, § 1(b)(1), expressly permits the defendant to postpone its revaluation until 1999, rendering moot any issues regarding P.A. 95-283 and P.A. 96-218. In P.A. 97-254, the legislature again addressed the ongoing issue of municipal revaluations that had occupied its attention since 1994. In subsection (b)(1) of P.A. 97-254, § 1, the legislature provided that: "The assessor or board of assessors of each town shall revalue all of the real estate in their respective municipalities in accordance with the schedule provided in this section. Nothing in this subsection shall be construed to prohibit a town from effecting more frequent revaluations between the implementation of each revaluation required in accordance with the provisions of this section. . . ." There then followed a three column table. The first column was titled "Town/City"; the second column was titled "Year of Next Revaluation"; and the third column was titled "Year of Subsequent Revaluation." For Norwalk, the year of the next revaluation was 1999, and the year of subsequent revaluation was 2003. It is clear from the language of P.A. 97-254, § 1(b)(1), which is consistent with its legislative history; see Conn. Joint Standing Committee Hearings, Finance, Revenue and Bonding, Pt. 3, 1997 Sess., pp. 799-800, 824-25, 908-909, 978, 1020, 1025-26; 40 S. Proc., Pt. 6, 1997 Sess., p. 1849; 40 S. Proc., Pt. 12, 1997 Sess., pp. 4014-16, 4037-38; 40 H.R. Proc., Pt. 18, 1997 Sess., pp. 6755-61; that the defendant may continue to postpone its revaluation until 1999. The plaintiff's challenge to the defendant's postponement of the revaluation must, therefore, fail.