Katz, J.
The principal issues in this tax appeal are: (1) whether the appeal by the plaintiff, Carol Manage[25]*25ment Corporation, from the decision of the defendant, the Greenwich board of tax review, pursuant to General Statutes (Rev. to 1987) § 12-1181 is collaterally estopped by an earlier action brought by the plaintiff pursuant to General Statutes § 12-119;2 and (2) whether [26]*26the trial court incorrectly determined, contrary to the decision of the defendant, that the plaintiffs property had been overvalued by the tax assessor of the town of Greenwich. We answer both of these questions in the negative and affirm the judgment of the trial court.
The following facts are undisputed. The plaintiff’s property, located at 25 West Elm Street in Greenwich, is a six-story brick apartment building containing fifty-three units of living space and garage space for thirteen vehicles. On October 1, 1979, in connection with a decennial revaluation mandated by General Statutes (Rev. to 1979) § 12-62,3 the Greenwich tax assessor determined that the fair market value of the property was $3,296,300. This translated into an assessed value of $2,307,410 ($742,000 for the land and $1,565,410 for the building).4
In 1983, the plaintiff5 filed a two count complaint in the Superior Court challenging the assessment. In the first count, the plaintiff sought relief under § 12-118 from its 1979,1980 and 1981 tax assessments. In the second count, the plaintiff claimed, pursuant to [27]*27§ 12-119, that the assessments were “manifestly excessive and could not have been arrived at except by disregarding the provisions of the statutes for determining the valuation of such property. . . .” The trial court, Hon. Raymond J. Devlin, state trial referee, rendered judgment for the defendant on both counts. As to the first count, the court found that the plaintiff had not challenged the assessment before the defendant pursuant to General Statutes § 12-111.6 Because a party may only appeal under § 12-118 from the action of a board of tax review, and the plaintiffs claim had never come before the defendant, the court rendered judgment for the defendant. With regard to the second count, the court found that the plaintiff had not met its burden of proof under § 12-119 and rendered judgment for the defendant on the merits.7
In 1985, the plaintiff appealed the 1984 assessment of its property to the defendant pursuant to § 12-111. The defendant refused to grant relief. The plaintiff then filed a complaint in the Superior Court pursuant to § 12-118 challenging the defendant’s denial of relief. In 1986, the plaintiff-amended its complaint to include a challenge to the 1985 and 1986 assessments of its property, and to add a second count directly challenging the assessments of its property pursuant to § 12-119.8 The defendant answered the complaint and raised the special defense of res judicata.
In an October 12, 1988 motion for summary judgment, the defendant claimed that the 1984 decision by Judge Devlin on the § 12-119 claim precluded the plaintiff’s § 12-118 appeal under principles of collateral [28]*28estoppel. On January 6, 1989, the court, Ryan, J., rejected the defendant’s collateral estoppel argument because of the “distinction in the standard of review between § 12-118 and § 12-119.” The court therefore denied the defendant’s motion for summary judgment as to the first count of the plaintiff’s complaint.9 The defendant subsequently amended its answer to assert collateral estoppel as a special defense to the plaintiff’s § 12-118 appeal.
After trial, the court, Lewis, J., rendered judgment for the plaintiff on its § 12-118 appeal. In its November 13, 1992 memorandum of decision, the trial court also rejected the defendant's collateral estoppel defense because of “the vast difference between § [12-118] appeals and § [12-119] law suits.”10 In addressing the merits of the plaintiffs claim, the court found that there was no reasonable probability that the plaintiff’s building would be converted to condominium use, and concluded, therefore, contrary to the claim of the defendant’s appraiser, that the highest and best use of the plaintiff’s property was its actual use as rental apartments. The court also found that the comparable sales method, the preferred method for valuing rental property under General Statutes § 12-63b,11 was the [29]*29proper method of appraisal. The court accepted the opinion of the plaintiff’s appraiser that the fair market value12 of the property was $2,400,000, rather than $3,296,300. The plaintiff’s appraiser arrived at this figure by comparing the plaintiff’s property with three similar apartment houses that were sold in 1981.13 The court rejected the claim of the defendant’s appraiser that the capitalization of income approach was the most appropriate method of valuation. The court held that the plaintiff was entitled to a refund or credit for any excess payments made to the town of Greenwich for the 1984 and subsequent tax years.
The defendant appealed from the judgment of the trial court to the Appellate Court, and we transferred the appeal to this court pursuant to Practice Book § 4023 and General Statutes § 51-199 (c). The defendant claims that: (1) the plaintiff’s § 12-118 appeal should have been barred because Judge Devlin’s 1984 decision [30]*30pursuant to § 12-119 “collaterally encompassed the criteria for determining fair market value under § 12-118”; (2) the trial court improperly rejected the cost of replacement approach used by the Greenwich tax assessor to value the plaintiffs property; (3) the trial court incorrectly determined that conversion to condominiums was not the highest and best use of the plaintiffs property; and (4) the trial court’s reliance on the report and testimony of the plaintiffs appraiser was clearly erroneous because that evidence conflicted with testimony given by the same appraiser in an earlier case. We reject all of these claims.
I
Because the defendant’s collateral estoppel claim, if valid, would dispose of this appeal, we consider it first. The defendant claims that the trial court incorrectly determined that the plaintiff’s appeal under § 12-118 was not collaterally estopped by Judge Devlin’s earlier judgment under § 12-119. We disagree.
In Second Stone Ridge Cooperative Corp. v. Bridgeport, 220 Conn. 335, 339-40, 597 A.2d 326 (1991), we distinguished appeals brought pursuant to §§ 12-111 and 12-118 from direct actions brought pursuant to § 12-119. Sections 12-111 and 12-118 “ ‘provide a method by which an owner of property may directly call in question the valuation placed by assessors upon his property by an appeal to the board of [tax review for] relief, and from it to the courts. . . . These statutes limit to a short period the time within which the property owner can seek relief under them, and the purpose of this is undoubtedly to prevent delays in the ultimate determination of the amounts a municipality can collect as taxes.’ Cohn v. Hartford, 130 Conn. 699, 702, 37 A.2d 237 (1944).
“On the other hand, § 12-119 allows a taxpayer one year to bring a claim that the tax was imposed by a [31]*31town that had no authority to tax the subject property, or that the assessment was ‘manifestly excessive and could not have been arrived at except by disregarding the provisions of the statutes for determining the valuation of [the real] property . . . .’ (Emphasis added.) Our case law makes clear that a claim that an assessment is ‘excessive’ is not enough to support an action under this statute. Instead, § 12-119 requires an allegation that something more than mere valuation is at issue. It is this element that distinguishes § 12-119 from its more frequently invoked companion, § 12-118.” Second Stone Ridge Cooperative Corp. v. Bridgeport, supra; see also Wilson v. Kelley, 224 Conn. 110, 118, 617 A.2d 433 (1992).
The defendant acknowledges the distinctions between the two statutes and concedes that Judge Devlin in the 1984 case dismissed the plaintiffs § 12-118 appeal without reaching its merits. The defendant nevertheless argues that in deciding the merits of the plaintiff’s § 12-119 claim, Judge Devlin did not limit his consideration to whether the assessment was manifestly excessive or arrived at in disregard of the statutory provisions governing property valuation; rather, he employed the standard of review applicable to § 12-118 appeals and considered whether the plaintiff’s property had been substantially overvalued. Specifically, the defendant asserts that Judge Devlin’s comments on the “wide variance in the appraisal figure[s] submitted,” and on his power to accept so much of the testimony of the appraisal experts as he found reasonable, indicate that he was considering issues beyond what is required for a § 12-119 claim. According to the defendant, these comments, coupled with citations to cases decided under § 12-118, demonstrate that Judge Devlin did not narrowly confine his consideration to whether there was misfeasance or nonfeasance by the taxing authority, or whether the assessment was arbitrary or so [32]*32excessive or discriminatory as to demonstrate a disregard of duty by the assessors. The defendant claims that in deciding whether the assessment was manifestly excessive, Judge Devlin applied the rule of valuation from § 12-63, which applies to § 12-118 appeals as well as § 12-119 actions, and determined whether the assessment reflected the fair market value of the property. The defendant accordingly asserts that because Judge Devlin, in resolving the § 12-119 claim, incidentally decided valuation issues pertinent to a § 12-118 claim in favor of the defendant, the plaintiff should have been barred from relitigating these issues. We disagree.
Res judicata and collateral estoppel “express no more than the fundamental principle that once a matter has been fully and fairly litigated, and finally decided, it comes to rest.” State v. Ellis, 197 Conn. 436, 464-65, 497 A.2d 974 (1985), on appeal after remand sub nom. State v. Paradise, 213 Conn. 388, 567 A.2d 1221 (1990). “Collateral estoppel, or issue preclusion, is that aspect of res judicata which prohibits the relitigation of an issue when that issue was actually litigated and necessarily determined in a prior action between the same parties upon a different claim.” (Emphasis added.) In re Juvenile Appeal (83-DE), 190 Conn. 310, 316, 460 A.2d 1277 (1983). “ ‘For an issue to be subject to collateral estoppel, it must have been fully and fairly litigated in the first action. It also must have been actually decided and the decision must have been necessary to the judgment.’ ” (Emphasis added.) Virgo v. Lyons, 209 Conn. 497, 501, 551 A.2d 1243 (1988); see also Ashe v. Swenson, 397 U.S. 436, 443, 90 S. Ct. 1189, 25 L. Ed. 2d 469 (1970); State v. Hope, 215 Conn. 570, 584, 577 A.2d 1000 (1990), cert. denied, 498 U.S. 1089, 111 S. Ct. 968,112 L. Ed. 2d 1054 (1991). “An issue is ‘actually litigated’ if it is properly raised in the pleadings or otherwise, submitted for determination, and in fact determined. (Emphasis added.) 1 Restatement (Sec[33]*33ond), Judgments § 27, comment (d) (1982). An issue is necessarily determined if, ‘in the absence of a determination of the issue, the judgment could not have been validly rendered.’ F. James & G. Hazard, Civil Procedure (3d Ed. 1985) § 11.19. If an issue has been determined, but the judgment is not dependent upon the determination of the issue, the parties may relitigate the issue in a subsequent action. Findings on nonessential issues usually have the characteristics of dicta. 1 Restatement (Second), Judgments § 27, comment (h) (1982).” (Emphasis in original.) Jackson v. R. G. Whipple, Inc., 225 Conn. 705, 714-15, 627 A.2d 374 (1993).
The defendant argues that because Judge Devlin used the criteria for determining the reasonableness of valuation under § 12-118 in his consideration of the plaintiffs direct action under § 12-119, those findings should have precluded the plaintiff from relitigating the claim. Both Judge Ryan, in ruling on the motion for summary judgment, and Judge Lewis, in trying the first count, rejected the defendant’s contention that Judge Devlin’s decision had collateral estoppel effect on this action, in light of the well recognized distinctions between the two statutes.
There is another and more compelling reason why the defendant’s argument must fail. Although it was essential to the decision of a § 12-119 claim for Judge Devlin to examine whether § 12-63 had been followed, he did not determine as part of his disposition of the § 12-119 claim what constituted the highest and best use of the property in 1979, a decision Judge Lewis was later called upon to make in connection with the § 12-118 appeal. In response to a motion to clarify his March 7,1984 decision, Judge Devlin stated that he had not specifically determined the highest and best use of the plaintiff’s property, although it “was an element an appraiser was entitled to take into consideration in his determination of the fair market value.”
[34]*34Consideration of the highest and best use has been recognized by this court as a valid part of any fair market value determination. Section 12-6314 indicates that the standard for valuation is the property’s “present true and actual value,” which is synonymous with “market value, actual value, fair market value, market price and fair value . . . .” Uniroyal, Inc. v. Board of Tax Review, 182 Conn. 619, 623 n.3, 438 A.2d 782 (1981). “Fair market value” is defined as “the value that would be fixed in fair negotiations between a desirous buyer and a willing seller, neither under any undue compulsion to make a deal . . . .” (Internal quotation marks omitted.) Uniroyal, Inc. v. Board of Tax Review, 174 Conn. 380, 390, 389 A.2d 734 (1978). A further definition is found in Mazzola v. Commissioner of Transportation, 175 Conn. 576, 581-82, 402 A.2d 786 (1978), to the effect that fair market value “is the price that a willing buyer would pay a willing seller based on the highest and best possible use of the land assuming, of course, that a market exists for such optimum use.” See also Whitney Center, Inc. v. Hamden, 4 Conn. App. 426, 428, 494 A.2d 624 (1985) (“[a]n assessment of land at its fair value, of necessity, regardless of the method of valuation, takes into account the highest and best value of the land”). As we said in State National Bank v. Planning & Zoning Commission, 156 Conn. 99, 101, 239 A.2d 528 (1968), “[t]he ‘highest and best use’ concept, chiefly employed as a starting point in estimating the value of real estate by appraisers, has to do with the use which will most likely produce the highest market value, greatest financial return, or the most profit from the use of a particular piece of real estate.”
We read Judge Devlin’s decision to reflect approval of the assessor’s use of § 12-63 as a means of assessment, and to hold merely that such consideration by [35]*35the assessor had not been inappropriate and did not result in a manifestly illegal appraisal. Therefore, although consideration of the assessor’s reliance on § 12-63 had indeed been part of the court’s decision as to whether the assessment was manifestly excessive or whether it had been arrived at in disregard of the statutes governing property valuation, Judge Devlin specifically refused to make auxiliary findings as to what actually constituted the highest and best use of the property in 1979.
Regardless of whether Judge Devlin journeyed beyond what was essential for a determination of the § 12-119 claim, he did not make factual findings that would collaterally estop a later court from deciding the value of the property. The issue raised by the § 12-119 appeal was whether the relevant statutes had been properly applied by the assessor. On the other hand, the issue raised by the § 12-118 appeal concerned what actually constituted the fair market value of the property as ascertained by a decision about its highest and best use. The earlier decision, therefore, did not have any preclusive effect upon the later court’s ability to decide the case before it.
II
The defendant next claims that the trial court incorrectly determined, contrary to the decision of the defendant, that the plaintiff’s property had been overvalued by the Greenwich tax assessor. More specifically, the defendant claims that the trial court: (1) improperly rejected the cost of replacement approach used by the Greenwich tax assessor to value the plaintiff’s property; (2) incorrectly determined that conversion to condominiums was not the highest and best use of the plaintiff’s property; and (3) improperly relied on the report and testimony of the plaintiff’s appraiser [36]*36because that evidence conflicted with testimony given by the same appraiser in an earlier case. We reject each of these claims.
A
First, the defendant claims that the trial court improperly rejected the cost of replacement approach used by the Greenwich tax assessor to value the plaintiffs property. The defendant argues that because the plaintiff did not offer any direct evidence that the assessor’s analysis was erroneous, the trial court should have given deference to the assessor’s judgment and upheld the initial assessment. We disagree.
The trial court in a § 12-118 appeal hears the case de novo; Stamford Apartments Co. v. Stamford, 203 Conn. 586, 588, 525 A.2d 1327 (1987); and has “ ‘ “the right to accept so much of the testimony of the experts and the recognized appraisal methods which they employed as [it] finds applicable . . . ’ (Emphasis added.) Pandolphe’s Auto Parts, Inc. v. Manchester, [181 Conn. 217, 221, 435 A.2d 24 (1980)], quoting Greenfield Development Co. v. Wood, 172 Conn. 446, 451, 374 A.2d 1084 (1977).” Stamford Apartments Co. v. Stamford, supra, 594.15 “While we have recognized that proper deference should be accorded to the assessor’s valuation ... no deference to the assessor's valuation [is] warranted” when neither the assessor nor the appraiser who valued the property during the revaluation testifies at trial. Id., 589.
[37]*37It appears from the record that neither the assessor nor the person who appraised the plaintiffs property in 1979 testified before the trial court. The only evidence pointed to by the defendant concerning the methodology employed in the assessment is the assessor’s card and the previously recorded testimony of Albert G. Kirk, who became the Greenwich assessor in December, 1979. Kirk testified that it appeared from the assessor’s card that a cost of replacement approach had been used to value the plaintiff’s property. He stated that he had no way of knowing, however, whether other approaches had even been considered.
In the absence of any evidence on why the assessor used the cost of replacement approach to value the plaintiff’s property and how the values in the assessment were calculated, deference to the assessor’s valuation was not required. Further, both Robert L. Levy, the plaintiff’s appraiser, and Michael Gold, the defendant’s appraiser, testified that the cost of replacement approach was the least valuable method of valuing the plaintiffs property. The Greenwich assessor at the time of trial, John P. Grecco, Jr., also testified that the cost of replacement approach was the worst method and the comparable sales approach was the best method of valuing an apartment building. It therefore was not improper for the trial court to reject the cost of replacement approach and the assessor’s valuation.16
[38]*38B
The defendant next claims that the trial court incorrectly determined that conversion to condominiums was not the highest and best use of the plaintiffs property. The defendant argues that this determination was incorrect because: (1) the trial court relied on testimony offered by the plaintiff that, at the time of the revaluation in October, 1979, it had no intention of converting its apartment building into condominiums; and (2) the trial court’s acceptance of Levy’s comparable sales analysis, which was based on the assumption that the building would be converted to condominiums, is inconsistent with its determination. We reject these arguments.
The parties agree that, while property should be valued according to its highest and best use, the valuation of an apartment building may be based on its potential conversion to condominiums only if conversion is reasonably probable in the near future. See Stamford Apartments Co. v. Stamford, supra, 592. The highest and best use of a property and the reasonable probability of conversion are questions of fact for the trier of fact. Id., 592-93; see Greene v. Burns, 221 Conn. 736, 748, 607 A.2d 402 (1992). We will not “substitute our evaluation of the evidence for that of the trial court . . . .” Stamford Apartments Co. v. Stamford, supra, 593.
The defendant argues that the trial court relied on the plaintiff’s subjective intent in determining whether conversion was reasonably probable.17 We disagree. [39]*39The court cited a number of factors, in addition to the plaintiffs intent, that contributed to its determination, including high conversion costs,18 weak demand for converted condominiums,19 a shortage of rental apartments,20 and changes in legislative policy providing enhanced protection against eviction for the elderly.21 These findings are adequately supported by the record and therefore will not be disturbed.
The defendant also argues that the trial court’s finding that conversion was not reasonably probable is inconsistent with its acceptance of Levy’s comparable sales analysis, because the analysis assumed conversion to condominiums. This argument is based on the fact that the three apartment buildings that Levy used in the analysis were all converted into condominiums. The trial court was aware of this implied inconsistency, and specifically noted that Levy’s analysis favored the defendant to the extent that the comparable buildings had been converted, even though conversion was not probable at the plaintiff’s building.
We have said that the “ ‘process of estimating the value of property for taxation is, at best, one of approx[40]*40imation and judgment, and there is a margin for a difference of opinion.’ Burritt Mutual Savings Bank v. New Britain, 146 Conn. 669, 675, 154 A.2d 608 (1959). ‘There may be more ways than one of estimating the value of such . . . [property] for taxation.’ Bridgeport Brass Co. v. Drew, 102 Conn. 206, 212, 128 A.2d 413 (1925).” Second Stone Ridge Cooperative Corp. v. Bridgeport, supra, 342. In accepting Levy’s analysis, the court relied in part upon General Statutes § 12-63b,22 which indicates that the comparable sales approach is the preferred method of valuing rental property. The court rejected the recommendation of Gold, the defendant’s appraiser, whose capitalization of income analysis relied much more heavily on conversion to condominiums.23 In light of § 12-63b and the evidence in the record, we conclude that the determination by the trial court that there was no reasonable probability of conversion to condominiums and the decision to accept the market value in accordance with Levy’s analysis were not clearly erroneous.
C
Finally, the defendant claims that the trial court’s reliance on the report and testimony of Levy, the plaintiffs appraiser, was clearly erroneous because that evidence conflicted with testimony given by Levy in an earlier case. We disagree.
Levy was the appraiser for the taxpayer in an earlier case, Stamford Apartments Co. v. Stamford, supra. In that case, Levy adjusted the results of his comparable sales analysis to reflect differences in interest rates on the revaluation date and on the sale dates of the com[41]*41parable properties. The defendant claims that a similar adjustment in this case would increase Levy’s appraisal of the plaintiff’s property using the comparable sales method to more than $4,000,000. During cross-examination, Levy conceded that the adjustment would have this effect. He testified that he did not believe that an adjustment was warranted in this case, however, because the Greenwich market differed from the Stamford market.
We have long held that “[t]he question of evaluating the credibility of the appraisers is for the trial court, not this court. Pandolphe’s Auto Parts, Inc. v. Manchester, [supra, 220-21]; see also Uniroyal, Inc. v. Board of Tax Review, [supra, 174 Conn. 387].” Stamford Apartments Co. v. Stamford, supra, 592. This court “cannot retry the facts or pass upon the credibility of the witnesses.” (Internal quotation marks omitted.) Pandolphe’s Auto Parts, Inc. v. Manchester, supra, 220. “[W]here the factual basis of the court’s decision is challenged we must determine whether the facts set out in the memorandum of decision are supported by the evidence or whether, in light of the evidence and the pleadings in the whole record, those facts are clearly erroneous.” Id., 221-22.
The trial court gave the defendant ample opportunity to challenge Levy’s credibility. The defendant was permitted to cross-examine Levy extensively about the evidence he had given in the earlier case, and to introduce portions of that evidence as exhibits. In his November 13, 1992 memorandum of decision, Judge Lewis specifically stated, “I find the testimony of the plaintiff’s appraiser to be credible.” After reviewing the evidence in the record, we cannot say that that finding was clearly erroneous.
The judgment is affirmed.
In this opinion the other justices concurred.