OPINION
ZAPPALA, Justice.The question in this appeal is whether the Plaintiffs/Appellees have standing to maintain the underlying action for declaratory relief against the Defendants/Appellants.
The facts are not in dispute. The Upper Bucks County Area Vocational-Technical School is operated by a Joint Committee formed by the Quakertown, Pennridge, and Palisades School Districts for the purpose of providing a vocational-technical education program to the residents of the districts. For the most part, students enrolled in the VoTech program attend one-half day of academic classes in their home districts and one-half day of instruction at the Vo-Tech facility.
The 1980-81 school year at the Vo-Tech school was scheduled to begin on September 2, 1980 and to end on June 9, 1981. Also scheduled were eight in-service days for teachers — two before, four during, and two after the students’ school year. A strike by members of the Vo-Tech faculty *421delayed the start of Vo-Tech instruction until September 24, 1980. The home school districts were open during this period, and students enrolled in the Vo-Tech program remained at their home schools during the half-days that they would otherwise have gone to the Vo-Tech facility. As a result of the strike, sixteen instruction days were lost from the Vo-Tech program. The Joint Committee, on October 16, 1980, approved a calendar for the school year identical to that which had been issued prior to the school year, thereby failing to make up the days lost because of the strike.
The present action was commenced in the Court of Common Pleas of Bucks County by individuals alleged to be teachers and taxpayers, and by the collective bargaining unit representing the teachers. The action sought a declaratory judgment declaring that the Joint Committee is required to operate the Vo-Tech school for 180 days in accordance with 24 Pa.C.S. § 15-1501, or in the alternative by virtue of regulations of the Department of Education and program plans submitted to the Department by the Committee. The action also requested an order directing the Committee to revise its 1980-81 schedule to include 180 days of instruction.
The Court of Common Pleas sitting en banc dismissed the action on the preliminary objections of the Joint Committee, holding that none of the plaintiffs had standing to bring the action. The Commonwealth Court 69 Pa.Cmwlth. 85, 450 A.2d 295 sitting en banc reversed, determining that the individual plaintiffs had standing as taxpayers to seek the desired relief. The Commonwealth Court did not address the question whether the individuals as teachers, or their union, had standing.
The essence of the standing requirement as articulated by this Court is that “[a] plaintiff ... must allege and prove an interest in the outcome of the suit which surpasses ‘the common interest of all citizens in procuring obedience to the law’ ... To surpass the common interest, the interest is required to be, at least, substantial, direct, and immediate.” Application of Biester, 487 Pa. 438, 442-43, 409 A.2d 848, *422851 (1979), citing Wm. Penn Parking Garage v. City of Pittsburgh, 464 Pa. 168, 346 A.2d 269 (1975).
“The requirement that an interest be ‘direct’ simply means that the person claiming to be aggrieved must show causation of harm to his interest by the matter of which he complains.” Wm. Penn, 464 Pa. at 195, 346 A.2d at 282 (emphasis added). The Appellees argue, and the Commonwealth Court held, that as taxpayers of the constituent school districts they have an interest which is harmed by the failure of the Committee to schedule 180 days, because the districts will lose a pro rata portion of a state subsidy for each day less than 180. We cannot agree. Nowhere in the complaint or in the record is there an allegation or evidence that links the loss of the subsidy with the plaintiffs’ interest as taxpayers. The plaintiffs do not allege that the loss of the subsidy will in any way affect their status as taxpayers, for example, by causing a tax increase to offset the lost funding. Although “[cjertain cases exist which grant standing to taxpayers where their interest arguably does not meet the requirements of Wm. Penn," Application of Biester, 487 Pa. at 444, 409 A.2d at 852, these cases are explained by the policy of ensuring judicial review which otherwise would not occur. “This will most often occur when those directly and immediately affected ... are beneficially affected as opposed to adversely affected.” Id. 487 Pa. at 445, 409 A.2d at 852. We find that the Commonwealth Court erred in determining that this is such a case. A careful reading reveals that the exceptional cases referred to in Biester involve situations where there is some degree of causal connection between the action complained of and the injury alleged, although it is too small to ordinarily confer standing. We reiterate that in the present case, reading the record and drawing all inferences in light most favorable to the plaintiffs, there is no connection between the failure of the Committee to schedule 180 days and harm to the plaintiffs in their status as taxpayers.
The individual Appellees also argue as a basis for standing their status as teachers whose contract rights to com*423pensation and computation of retirement and other benefits are adversely affected by the failure of Appellants to schedule 180 days in compliance with either the statute or Department of Education regulations. The Appellee union argues standing derived from this standing of its members.
Within the requirement that the interest of the plaintiff be “immediate” in order to confer standing, is the concept that the “protection of the type of interest asserted is among the policies underlying the legal rule relied upon by the person claiming to be 'aggrieved’.” Wm. Penn, 464 Pa. at 198, 346 A.2d at 284. The United States Supreme Court has phrased this guideline as whether “the interest the plaintiff seeks to protect is arguably within the zone of interests sought to be protected by the statute or constitutional guarantee in question.” Association of Data Processing Service Organizations, Inc. v. Camp, 397 U.S. 150, 90 S.Ct. 827, 25 L.Ed.2d 184 (1970). We think it is clear that the sole purpose of the 180-day requirement contained in the statute and in the departmental regulations is to benefit the students of the Commonwealth. Any benefit to the teachers arising out of its operation or non-operation is purely incidental, and not within the zone of interests sought to be protected. Accordingly, the individual plaintiffs as teachers, and the union as their representative, do not have such an immediate interest as to confer standing to maintain the present action.
The order of the Commonwealth Court is reversed, and the order of the Court of Common Pleas of Bucks County is reinstated.
HUTCHINSON, J., filed a concurring opinion. LARSEN, J., filed a dissenting opinion.