PETERS, C.J.

The principal issue in this appeal is whether a New York corporation having its primary place of business in Connecticut has engaged in sufficient activity in New York to satisfy the "conducts business" requirement of General Statutes (Rev. to 1985) 12-218, thereby qualifying the corporation for an apportionment of its taxable income between Connecticut and New York. The plaintiff, Altray Company, Inc. (taxpayer), sought to amend three previously filed tax returns, upon which it had paid Connecticut corporation income taxes, because it claimed the right to apportion income to New York. The defendant, the commissioner of revenue services (commissioner), denied the amended returns and the corresponding request for refund of a portion of the taxes previously paid. The taxpayer sought review in the Superior Court of the commissioner's final decision denying the refund request. The trial court dismissed the appeal. The taxpayer 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). We reverse the judgment of the trial court.

The parties stipulated to the following facts. The taxpayer is a New York corporation with its principal place of business in Greenwich, Connecticut. It is engaged in the import business and primarily acts as an agent facilitating domestic purchases of candies and confectioneries from foreign vendors. In the course of this business, the taxpayer purchases and resells the candies, and arranges to have them shipped from foreign vendors and delivered to subsequent purchasers' warehouses located in states other than Connecticut and New York.

During 1983, 1984 and 1985, the taxpayer augmented the business conducted at its Connecticut office through its president's numerous, repeated and regular meetings with foreign vendors at his residential apartment in New York City. These meetings averaged in number approximately three per month. At these meetings, held in New York for the convenience of visiting overseas suppliers, the taxpayer placed orders with the foreign vendors.

Because of its incorporation in New York, the taxpayer was subject to that state's corporation franchise tax. For the relevant income years it paid the statutory minimum tax due to New York. The taxpayer also paid taxes to Connecticut for the privilege of carrying on business in this state, pursuant to General Statutes (Rev. to 1985) 12-214. In its original returns, filed in 1983, 1984 and 1985, the taxpayer paid the Connecticut tax measured by its entire net income. In 1986, however, the taxpayer filed amended returns for the three prior years that apportioned its net income between Connecticut and New York. Pursuant to this apportionment, the taxpayer recalculated its previously paid Connecticut corporation taxes due. Because this recalculation resulted in a claimed reduction of its tax liability, the taxpayer requested a refund of excess taxes paid, with interest.

The commissioner denied the amended returns, determining that the taxpayer "does not conduct business without the State of Connecticut." The taxpayer protested this denial, and requested a hearing before the commissioner so that it could present additional evidence regarding its right to apportion its income between Connecticut and New York. After the hearing, the commissioner issued a final order denying the taxpayer's protest. It concluded that "[t]his company has not established that it conducts business outside of Connecticut . . . . The audit assessment is found to be correct and lawful." The commissioner neither decided nor addressed the merits of the taxpayer's position regarding the amount of the claimed refund or the figures offered to support the refund amount in the event that apportionment should be allowed.

The taxpayer appealed to the Superior Court pursuant to General Statutes (Rev. to 1985) 12-237, complaining that it was entitled to apportion its income. Specifically, the taxpayer maintained that its activity in New York amounted to conducting business for the purpose of 12-218. The taxpayer also maintained that, even if its activity was not sufficient to allow apportionment, the commissioner was estopped in this case from denying the claim for a refund. Finally, the taxpayer sought a judgment awarding it the full amount of its requested refund instead of a remand to the commissioner.

The trial court, following a de novo review of the taxpayer's claim, dismissed the appeal. The trial court determined that 12-218 was a tax exemption statute that should be construed against the taxpayer. The trial court also determined that the proper meaning of the 12-218 "conducts business" requirement was "carrying on business" as defined in related tax provisions and that, pursuant to that standard, the taxpayer had not conducted business in New York. The trial court dismissed the taxpayer's estoppel argument on the grounds that the commissioner's response was neither binding on the commissioner nor had it been relied upon by the taxpayer.

On appeal, the taxpayer challenges the trial court's determination that it did not conduct business in New York during the income years 1983, 1984 and 1985. The taxpayer claims that: (1) the trial court improperly determined that 12-218 is a tax statute that provides an exemption rather than one that imposes a tax; (2) the trial court improperly interpreted the "conducts business" requirement in 12-218 in disregard of the commissioner's pretrial discovery statement adopting a standard that would give legal effect to the taxpayer's incorporation in New York; (3) the trial court, under any reasonable construction of the "conducts business" requirement of 12-218, misapplied that requirement in light of the taxpayer's stipulated New York activities; and (4) if this court sustains its appeal, it has established its entitlement to a refund in the amount requested. Our review of these claims is plenary; see Morton Buildings, Inc. v. Bannon, 222 Conn. 49, 53, 607 A.2d 424 (1992); and we will reverse the trial court if its conclusions are legally or logically incorrect or find no support in the facts that appear in the record. Id.; United Illuminating Co. v. Groppo, 220 Conn. 749, 752, 601 A.2d 1005 (1992); Pandolphe's Auto Parts, Inc. v. Manchester, 181 Conn. 217, 221-22, 435 A.2d 24 (1980). Because we agree with the taxpayer, first, that the apportionment provision is an imposition statute, and, second, that the taxpayer satisfies even the commissioner's standard for "conducts business," the appeal must be sustained.

I

As a preliminary matter, the taxpayer asks us to review the trial court's determination that 12-218 is properly considered a tax exemption statute, and not a tax imposition statute. If a statute that imposes a tax is ambiguous either on its face or in its application, a taxpayer is entitled to a construction in its favor; conversely, a statute providing for a tax exemption must be construed in favor of the state. Morton Buildings, Inc. v. Bannon, supra, 54; The B. F. Goodrich Co. v. Dubno, 196 Conn. 1, 6, 490 A.2d 991 (1985); Hartford Electric Light Co. v. Sullivan, 161 Conn. 145, 154, 285 A.2d 352 (1971). We agree with the taxpayer that 12-218 involves the imposition of a tax, and, therefore, that any ambiguity must be resolved in its favor and against the commissioner.

In Schlumberger Technology Corporation v. Dubno, 202 Conn. 412, 423, 521 A.2d 569 (1987), which addressed the construction of the apportionment formulae provisions of 12-218, we resolved ambiguities in the statute in favor of the taxpayer. See also The B. F. Goodrich Co. v. Dubno, supra. Although our decision did not turn on an explicit determination that 12-218 was an imposition statute, we now hold that this is the proper characterization and rule of construction to apply in cases involving disputes over any provision of 12-218.

The apportionment statute, although itself not a taxing statute, provides the criteria and formulae for determining net income subject to the state's corporation tax. Section 12-214, which imposes the corporation tax, provides that the tax is "to be measured by the entire net income . . . from business transacted within the state during the income year." (Emphasis added.) Significantly, 12-214 does not provide any guidance to determine the measure of "business transacted within the state." Such guidance is found, however, in 12-218. That section states that a taxpayer is to apply the formula "provided in this section" to calculate net income taxable within this state. Because 12-218 is an integral component of this state's tax imposition scheme; see also Texaco Refining Marketing Co. v. Commissioner, 202 Conn. 583, 594, 522 A.2d 771 (1987); it cannot properly be characterized as a statute providing a taxpayer exemption.

The commissioner resists this characterization on the ground that apportionment of net income under 12-218 operates to exclude from taxation a portion of corporate income otherwise subject to 12-214. Emphasizing that qualification for apportionment is a separate inquiry from application of the various apportioning formulae, the commissioner argues that cases such as Schlumberger Technology Corporation v. Dubno, supra, do not control the resolution of this appeal because, in those cases, neither the multistate nature of the corporation nor the resulting qualification to apportion income was at issue. Conceding that the application of apportionment formulae is an imposition of taxing authority; id., 423; the commissioner asserts nonetheless that the taxpayer's prerequisite showing that it qualifies for the right to apportion its net income requires the conclusion that 12-218 operates as an exemption provision for such purposes. In effect, the commissioner asks us to bifurcate the characterization of the apportionment statute. An analysis of whether a corporation qualifies to apportion income would proceed under 12-218 as a tax exemption statute; an analysis of questions regarding the application of apportionment formulae would proceed as if the statute imposed a tax.

We decline to adopt the commissioner's bifurcated analysis for two reasons. As a statutory matter, the commissioner's argument cannot be reconciled with the language 12-214, which limits the reach of the corporation tax to that income from business "transacted within this state." This statutory limitation mirrors the second difficulty with the commissioner's position, which is that it ignores established federal constitutional constraints on state taxation of interstate corporations.

Well established federal law limits the taxing power of a state in accordance with the provisions of the commerce and due process clauses of the federal constitution. See Complete Auto Transit, Inc. v. Brady, 430 U.S. 274, 279, 97 S.Ct. 1076, 51 L.Ed.2d 326, reh. denied, 430 U.S. 976, 97 S.Ct. 1669, 52 L.Ed.2d 371 (1977) (commerce clause); Mobil Oil Corporation v. Commissioner of Taxes of Vermont, 445 U.S. 425, 436-37, 100 S.Ct. 1223, 63 L.Ed.2d 510 (1980) (due process clause). Without apportionment, the state's corporation tax would be constitutionally suspect. Cf. Underwood Typewriter Co. v. Chamberlain, 254 U.S. 113, 41 S.Ct. 45, 65 L.Ed. 165 (1920). Because the state does not have the power to tax that portion of income attributable to activity outside its borders, the apportionment provisions necessarily operate to determine the extent of the state's power to impose a tax. Accordingly, the state cannot assert a right to impose a tax on a corporation's entire net income, regardless of its origin, and then characterize as an exemption the corporation's claim that the state lacked the authority to tax in the first instance.

We conclude, therefore, that in cases involving the right to apportion income under 12-218, as in other cases involving the imposition of a tax, the applicable principles of construction favor the taxpayer rather than the commissioner. Morton Buildings, Inc. v. Bannon, supra. In case of ambiguity in the governing statute, it must be construed in favor of the taxpayer.

II

Viewing 12-218 as a statute that imposes a tax, we now turn to the substantive issue of the application of its apportionment requirement to the taxpayer in this case. We must decide how to construe the provision in 12-218 that "[f]or purposes of apportionment of income under this section, a taxpayer is taxable in another state if in such state such taxpayer conducts business," and then apply the statute to the stipulated facts concerning the taxpayer's commercial conduct in New York.

The phrase "conducts business" is not defined either by statute or by a properly promulgated tax regulation. The commissioner proposes that we construe "conducts business" to be the equivalent of "carrying on business," as that phrase is used in other provisions of the corporation tax statutes and regulations. The taxpayer counters, however, that the commissioner has elsewhere embraced a broader rule encompassing not only "carrying on business," but also "the right to carry on business." The taxpayer relies, for this contention, on the commissioner's answer to a pretrial interrogatory that explicitly stated this broader test for the measure of "conducts business." The commissioner responds that the taxpayer has misconstrued its reply to the interrogatory, and continues to advance "carrying on business" as the proper test for "conducts business."

The taxpayer has assigned as a separate claim of error the trial court's alleged failure to give appropriate weight to the commissioner's reply to its interrogatory. We need not address that contention, however, because we conclude that the taxpayer's right to apportionment can be sustained even if we apply the commissioner's construction of "conducts business." Furthermore, an agency's construction of the statutes entrusted to it for enforcement is generally persuasive, even if it is not dispositive. See Phelps Dodge Copper Products Co. v. Groppo, 204 Conn. 122, 128-30, 527 A.2d 672 (1987); Texaco Refining Marketing Co. v. Commissioner of Revenue Services, supra, 599.

The commissioner's test equating "conducts business" with "carrying on business" refers us to the definition of "carrying on business" that appears in related corporate tax statutes and regulations. General Statutes (Rev. to 1985) 12-213 defines "carrying on or doing business" as "mean[ing] and includ[ing] each and every act, power or privilege exercised or enjoyed in this state, as an incident to, or by virtue of, the powers and privileges acquired by the nature of any [corporate] organization." This statutory definition is effectively narrowed, according to the commissioner, by the definition of "carrying on business" contained in 12-214-1(a) of the Regulations of Connecticut State Agencies. The regulation states that "[a] company is `carrying on business in this state' if, within this state, it engages in one or more of the following activities, including but not limited to: [e.g.] . . . (2) maintaining an office . . . (3) selling tangible personal property (as opposed to soliciting orders therefor) . . . (7) having an employee, wherever based . . . coordinate the delivery of merchandise." (Emphasis added.)

The taxpayer maintains that its meetings in New York meet the statutory definition of "carrying on business." During the period of years in issue in this case, the taxpayer had a regular practice of using New York, the state in which it was incorporated, for the negotiation and placement of orders from foreign vendors. These activities, the taxpayer insists, represent the essence of its business as an agent dealing in tangible goods and therefore manifest "each and every act, power or privilege exercised . . . as an incident to, or by virtue of" its incorporation in New York.

The commissioner, emphasizing his narrower regulation, maintains that the taxpayer was not "carrying on business" in New York because the taxpayer had no property or place of business, no payroll, and no sales in that state, and furthermore, that the taxpayer did not conduct there any of the activities listed in 12-214-1(a). Even if we accept the commissioner's incorporation by reference of the terms of 12-214-1(a), we are not persuaded that the regulation supports his argument. Although the activities representative of the taxpayer's business are not explicitly recognized in the regulation, 12-214-1(a) unequivocally provides that the list "includ[es], but [is] not limited to" the activities identified therein. The taxpayer claims that it negotiated for and made purchases of candies and confectioneries from foreign vendors. These meetings and purchases are virtually identical to the conduct of its business in Connecticut, and lie at the heart of its corporate purpose. Furthermore, this type of purchasing activity is not explicitly excluded from "carrying on business," as, for instance, is the mere solicitation of orders for tangible personal property.

Viewing the statute at issue as a statute imposing a tax and therefore construing any ambiguity in favor of the taxpayer, we agree with the taxpayer that it was "conducting business" because it was "carrying on business" under either 12-213 or 12-214-1(a). In Northeastern Pharmaceutical Chemical Co. v. Heffernan, 179 Conn. 363, 367-70, 426 A.2d 769 (1979), we held that a corporation was required to apportion losses out of state because another state could have imposed a franchise tax on the corporation, and the corporation's "activity" was only accrued losses on the sale of machinery and equipment as it was winding up its operation in that state. It is as appropriate to recognize that the taxpayer here may apportion its income out of state, although this may entail a lose of revenue for the state, as it was to require the corporation in Northeastern Pharmaceutical Chemical Co. v. Heffernan, supra, to apportion its losses out of state, thereby increasing this state's revenue. The commissioner must permit apportionment of income in the circumstances of this case.

III

Anticipating the possibility that the judgment of the trial court might be reversed, and the taxpayer's appeal sustained, the parties have addressed the framing of a proper remand. Although the taxpayer urges us to direct the entry of a judgment for a refund in the amount to which it claims to be entitled, we agree with the commissioner that such an order would be inappropriate. The record reflects that there has been no administrative determination of the validity or accuracy of the amount of the taxpayer's claimed refund. The parties stipulated to many of the relevant facts, but they did not stipulate to the amount of any refund. Further, the commissioner in his pleadings in the trial court denied the taxpayer's allegation that an uncontested refund amount was due. The plenary review that the statutes authorize for tax appeals; Kimberly-Clark Corporation v. Dubno, 204 Conn. 137, 144-45, 527 A.2d 679 (1987); presupposes an underlying administrative determination of fact. A remand to the commissioner is the appropriate course in the absence of such an administrative determination.