McHUGH, Justice:
In this appeal by the State Department of Tax and Revenue the primary issue is whether “speculative builders” were to be considered as engaged in the business of “contracting” for purposes of the consumers sales and service tax exemption and use tax exemption, at the time in controversy, for purchases of services, machinery, supplies and materials directly used or consumed in the business of “contracting.” Unlike the Circuit Court of Hancock County, West Virginia, we believe the then effective consumers sales and service tax and use tax regulations excluding “speculative builders” from the tax exemptions in question for those persons engaged in the business of “contracting” was valid; we also believe, unlike the circuit court, that this distinction between “speculative builders” and “contractors” under the then effective consumers sales and service tax and use tax exemption statutes did not violate equal protection principles. On the other hand, we believe the additions to tax and the tax penalties were vacated properly by the circuit court.
I
FACTS
From 1978 through 1982, the taxpayer-appellee, Tony P. Sellitti Construction Company, among other
business
activities, built houses on its
own
lots to its
own
specifications, without a construction contract, with the intent of selling the improved realty eventually to other persons.
In the type of business in question the taxpayer purchased and consumed or used various building materials and supplies from both instate and out-of-state vendors. For these purchases the taxpayer did not pay any consumers sales and service tax (in-state vendors) or use tax (out-of-state vendors).
The then State Tax Department (now the State Department of Tax and Revenue)
audited the taxpayer’s books and records, and the Business Tax Division of that Department thereafter issued an assessment for consumers sales and service tax and an assessment for use tax. The consumers sales and service tax was for the period January 1, 1978 through December 31, 1982, and the total amount assessed, including tax, interest, addition to tax and penalty, was $8,338.33.
The use tax assessment was for the period April 1, 1978 through December 31, 1982, and the total amount assessed, including tax, interest, addition to tax and penalty, was $23,-499.10.
The taxpayer timely petitioned for reassessment of the consumers sales and service tax and use tax liabilities, contending that it owed nothing for either of these taxes, as the purchases in question were directly used or consumed allegedly in the business of “contracting,” for which there was a tax exemption at the time in controversy under
W.Va.Code,
11-15-9(6) [1974] (consumers sales and service tax) and
W.Va.Code,
ll-15A-3(3) [1969] (use tax).
After an evidentiary hearing before the then State Tax Department’s Office of Hearings and Appeals, the two assessments were affirmed by the State Tax Commissioner as issued.
The taxpayer subsequently appealed timely to the Circuit Court of Hancock County. That court vacated the assessments. The circuit court held that the State Department of Tax and Revenue exceeded its authority in promulgating regulations which exclude “speculative builders” from the exemption for certain purchases by persons engaged in the business of “contracting.” The circuit court also held that the consumers sales and service tax exemption statute and the use tax exemption statute unconstitutionally denied equal protection, to the extent that those statutes distinguished between contractors and speculative builders.
The State Department of Tax and Revenue brought this appeal.
II
REGULATIONS ON SPECULATIVE BUILDERS
At the time in controversy the then State Tax Department had promulgated legislative rules and regulations for consumers sales and service tax and use tax purposes. Consumers and Use Tax Regulations (“C.U.T. Reg.”) § 1.6(A)(3)(c) (1974)
provided, in material part:
(c) Sales of property or services
to
persons engaged in this State in the business of
contracting,
manufacturing, transportation, transmission, communication, or in the production of natural resources [are exempt]. Said sales, to be
exempt,
must be confined to services,
machinery, supplies and materials directly used or consumed in the businesses named in the preceding sentence.
Persons in the business of
contracting,
manufacturing, transportation, transmission, communication, or in the production of natural resources may
purchase tangible personal property
and services
to be used or consumed in the construction of or permanent improvement of real estate without
imposition of consumers
tax on
such
purchases. All other persons, including
but not limited to
speculative builders
or persons constructing for resale,
must pay
consumers
tax on purchases of tangible personalty
and services
to be used or consumed in the construction of or permanent improvement of real estate.
(emphasis added)
Similarly, C.U.T. Reg. § 3.27 (1974) stated as follows:
Speculative Builders.
— Speculative or operative builders are engaged primarily in the construction or repair of real property
for sale or
rent and are deemed to be the ultimate consumers of all supplies, materials, or equipment used in the conduct of their business. Therefore, consumers tax is applicable to sales to such operative builders and services rendered for them, and use tax is applicable to their purchases from outside the State,
(emphasis added) C.U.T. Reg. § 3.27 (1974) was identical to a prior regulation, C.U.T. Reg. § 1.99 (1964, 1969).
These regulations distinguish between “speculative builders” and those persons engaged in the business of “contracting.” “Speculative builders” are engaged in the business activity of constructing improvements to real property which they own, in accordance with their own specifications, that is, they do not have a realty improvement contract with another person, and they construct the real property improvements under these circumstances, with the intent of selling the improved realty eventually to other persons. The basic “selling” nature of a “speculative builder’s” activities is also recognized in
Bassett v. City of Tucson,
137 Ariz. 199, 200, 669 P.2d 976, 977 (Ct.App.1983),
review denied
(Ariz. Sept. 15, 1983).
In contrast, “contractors” construct improvements to real property which other persons own, in accordance with the other persons’ specifications, that is, the realty improvement work or work and materials are furnished in the fulfillment of a realty improvement contract with another person.
See Koppers Co. v. Dailey,
167 W.Va. 521, 280 S.E.2d 248 (1981) (business and occupation tax case).
The consumers sales and service tax exemption and the use tax exemption, addressed by these regulations, and set forth in, respectively,
W.Va.Code,
11-15-9(6) [1974] and
W.Va.Code,
ll-15A-3(3) [1969],
see supra
note 5, are for certain purchases by persons engaged in certain businesses, including “contracting” businesses. The consumers sales and service tax and the use tax legislation at the time in controversy did not define “contracting” or any of the other businesses named in these exemptions. A “contracting” business was defined, however, by the related West Virginia business and occupation tax legislation at the time, specifically,
W.Va.Code,
11-13-1 [1972], which provided (in the last paragraph thereof) as follows: “ ‘Contracting’ shall include the furnishing of work, or both materials and work,
in the fulfill-
merit of a contract
for the construction, alteration, repair, decoration or improvement of a new or existing building or structure, or any part thereof, or for the alteration, improvement or development of real property.” (emphasis added)
This related statutory definition of “contracting” supports the regulations’ exclusion of “speculative builders” from the sales and use tax exemptions for certain purchases to be used or consumed directly in “contracting” businesses because
“speculative builders” do not work “in the fulfillment of a contract” for the improvement of real property; instead, they work for themselves.
For the same reason the taxpayer’s reliance upon
Stolze Lumber Co. v. Stratton,
386 Ill. 334, 54 N.E.2d 554 (1944), is misplaced. That case involved actual “contractors” working under realty improvement contracts with the owners of the premises.
Id.
at 335-36, 54 N.E.2d at 555. In contrast, in the present case the taxpayer in its speculative building activities did not work under realty improvement contracts with the owners of the premises; instead, it worked for itself.
Furthermore, the rules of statutory construction support the regulations in question excluding “speculative builders” from the sales and use tax statutory exemptions for certain purchases to be used or consumed directly in “contracting” businesses. First, “[w]here the language of the statute is of doubtful meaning or ambiguous, rules of construction may be resorted to and the construction of such statute by the person charged with the duty of executing the same is accorded great weight.” Syl. pt. 4,
Pennsylvania & West Virginia Supply Corp. v. Rose,
185 W.Va. 214, 368 S.E.2d 101 (1988) (upholding State Tax Department’s interpretation of another sales tax/ use tax statutory exemption). The consum
ers sales and service tax and use tax exemption statutes in question were ambiguous because the sales and use tax legislation at the time in controversy did not define “contracting.” The then State Tax Department reasonably could rely upon the related West Virginia business and occupation tax statute’s definition of “contracting,” which required the realty improvement work to be “in the fulfillment of a contract[,]” thereby excluding speculative builders, who work for themselves, not “in the fulfillment of a contract” for improvement of another person’s realty. This long-standing administrative interpretation is reasonable and is entitled to great weight.
A second rule of statutory construction applicable here is set forth in syllabus point 5 of
Pennsylvania & West Virginia Supply Corp. v. Rose,
185 W.Va. 214, 368 S.E.2d 101 (1988): “ ‘Where a person claims an exemption from a law imposing a license or tax, such law is strictly construed against the person claiming the exemption.’ Syl. Pt. 2,
State ex rel. Lambert v. Carman, State Tax Commissioner,
145 W.Va. 635, 116 S.E.2d 265 (I960).”
Consistent with the foregoing, this Court holds that the former consumers sales and service tax and use tax regulations excluding “speculative builders” from the former consumers sales and service tax and use tax statutory exemptions for purchases of services, machinery, supplies and materials directly used or consumed in the business of “contracting,”
W.Va.Code,
11-15-9(6) [1974] and
W.Va.Code,
ll-15A-3(3) [1969], were valid and enforceable during the time they were in effect.
Ill
EQUAL PROTECTION
The circuit court agreed with the taxpayer’s argument that the former sales and use tax exemption statutes in question were violative of the equal protection guarantees of the State
Constitution
if such statutes are interpreted as excluding “speculative builders” from the definition of “contracting” businesses. We disagree.
The generally applicable fundamental principle is that the powers of the legislature are almost plenary: “The Constitution of West Virginia being a restriction of power rather than a grant thereof, the legislature has the authority to enact any measure not inhibited thereby.” Syl. pt. 1,
Foster v. Cooper,
155 W.Va. 619, 186 S.E.2d 837 (1972).
Moreover, in light of the constitutionally required principle of the separation of powers among the judicial, legislative and executive branches of state government,
W.Va. Const.
art. V, § 1, courts ordinarily presume that legislation is constitutional, and the negation of legislative power must be shown clearly:
‘In considering the constitutionality of a legislative enactment, courts must exercise due restraint, in recognition of the principle of the separation of powers in government among the judicial, legislative and executive branches.
[W.Va. Const,
art. V, § 1.] Every reasonable construction must be resorted to by the courts in order to sustain constitutionality, and any reasonable doubt must be resolved in favor of the constitutionality of the legislative enactment in question. Courts are not concerned with questions relating to legislative policy. The general powers of the legislature, within constitutional limits, are almost plenary. In considering the constitutionality of an act of the legislature, the negation of legislative power must appear beyond reasonable doubt.’ Syl. pt. 1,
State ex rel.
Appalachian Power Co. v. Gainer,
149 W.Va. 740, 143 S.E.2d 351 (1965).
Syl. pt. 2,
West Virginia Public Employees Retirement System v. Dodd,
183 W.Va. 544, 396 S.E.2d 725 (1990).
Accord,
syl. pt. 1,
Lewis v. Canaan Valley Resorts, Inc.,
185 W.Va. 684, 408 S.E.2d 634 (1991).
See also
syl. pt. 1,
State ex rel. Haden v. Calco Awning & Window Corp.,
153 W.Va. 524, 170 S.E.2d 362 (1969) (upholding constitutionality of sales tax statutory section).
Accordingly, a facial challenge to the constitutionality of legislation is the most difficult challenge to mount successfully. The challenger must establish that no set of circumstances exists under which the legislation would be valid; the fact that the legislation might operate unconstitutionally under some conceivable set of circumstances is insufficient to render it wholly invalid.
Rust v. Sullivan,
— U.S. -, -, 111 S.Ct. 1759, -, 114 L.Ed.2d 233, -(1991).
We now turn specifically to equal protection challenges to legislation. This Court, in syllabus point 2 of
Israel v. West Virginia Secondary Schools Activities Commission,
182 W.Va. 454, 388 S.E.2d 480 (1989), observed that “[e]qual protection of the law is implicated when a classification treats similarly situated persons in a disadvantageous manner. The claimed discrimination must be a product of state action as distinguished from a purely private activity.”
Israel
finally settled, in syllabus point 4, where this state’s equal protection concepts, not expressly set forth in this state’s
Constitution,
are located implicitly: “West Virginia’s constitutional equal protection principle is a part of the Due Process Clause found in Article III, Section 10 of the West Virginia Constitution.”
See also
syl. pt. 3,
Robertson v. Goldman,
179 W.Va. 453, 369 S.E.2d 888 (1988). The scope of our equal protection concepts “is coextensive [with] or broader than that of the fourteenth amendment to the United States Constitution.”
Id.
(in part).
.
Most legislative classifications, including those which involve economic rights, such as taxation classifications, are subjected to a minimum level of scrutiny, specifically, the traditional equal protection concept that the legislative classification will be upheld if it is reasonably related to the achievement of a legitimate state purpose. We recently reformulated this “rational basis” type of equal protection analysis in syllabus point 4 of
Gibson v. West Virginia Department of Highways,
185 W.Va. 214, 406 S.E.2d 440 (1991):
“ ‘ “Where economic rights are concerned, we look to see whether the classification is a rational one based on social, economic, historic or geographic factors, whether it bears a reasonable relationship to a proper governmental purpose, and whether all persons within the class are treated equally. Where such classification is rational and bears the requisite reasonable relationship, the statute does not violate Section 10 of Article III of the West Virginia Constitution, which is our equal protection clause.” Syllabus Point 7, [as modified,]
Atchinson v. Erwin,
[172] W.Va. [8], 302 S.E.2d 78 (1983).’ Syllabus Point 4, as modified,
Hartsock-Flesher Candy Co. v. Wheeling Wholesale Grocery Co.,
174 W.Va. 538, 328 S.E.2d 144 (1984).”
Accord,
syl. pt. 2,
Lewis v. Canaan Valley Resorts, Inc.,
185 W.Va. 684, 408 S.E.2d 634 (1991).
Judge Haymond, writing for the Court in syllabus point 5 of
United Fuel Gas Co. v. Battle,
153 W.Va. 222, 167 S.E.2d 890,
appeal dismissed and cert. denied,
396 U.S. 116, 90 S.Ct. 398, 24 L.Ed.2d 309 (1969), stated this “rational basis” equal protection test in a similar fashion in a case rejecting a challenge to the constitutionality of a classification under the West Virginia business and occupation tax statute:
A state by its legislature may make reasonable classifications in enacting
statutes[,] provided the classifications are based on some real and substantial relation to the objects sought to be accomplished by the legislation, and a person who assails any such classification has the burden of showing that it is essentially arbitrary and unreasonable.
A corollary principle is that the judiciary may not sit as a superlegislature to judge the wisdom or desirability of legislative policy determinations made in areas that neither affect fundamental rights nor proceed along suspect lines.
City of New Orleans v. Dukes,
427 U.S. 297, 303, 96 S.Ct. 2513, 2517, 49 L.Ed.2d 511, 517 (1976).
Applying these principles to this case, we believe the distinction between “speculative builders” and “contractors” under the statutes in question does not deny equal protection. Speculative builders, who do not work under realty improvement contracts and who are, instead, essentially engaged in sales of their own improved realty, are rationally distinguished from “contractors,” who do work under such contracts with other persons who own the real estate lots. In addition, limiting the entitlement to sales and use tax exemptions for certain purchases by “contractors” to persons who are actual contractors is a legitimate governmental purpose. Finally, all persons actually in the “contracting” classification are treated the same under the statutes in question. As we stated in
Capitol Cablevision Corp. v. Hardesty,
168 W.Va. 631, 642-43, 285 S.E.2d 412, 419 (1981), “[wjhere ... the similarity between two businesses is only superficial and they make different products or perform different services, differential treatment in tax assessment will be upheld.”
Based upon the above, this Court holds that the former consumers sales and service tax and use tax exemptions for purchases of services, machinery, supplies and materials directly used or consumed in the business of “contracting,”
W.Va.Code,
11-15-9(6) [1974] and
W.Va.Code,
ll-15A-3(3) [1969], did not deny equal protection to “speculative builders” insofar as these statutory tax exemptions were interpreted as excluding “speculative builders” from the “contracting” classification.
IV
ADDITIONS TO TAX AND PENALTIES
By vacating the tax assessments in their entirety, the circuit court vacated the additions to tax and penalties, in addition to the actual tax amounts and accrued interest. While we believe the taxpayer is liable for the actual tax amounts of the assessments and the nonwaivable interest accruing to the date the tax is paid,
this Court concludes, on the other hand, that the circuit court correctly vacated the additions to tax and tax penalties.
W.Va. Code,
ll-10-18(a)(l)-(2) [1978, 1986] provide, in material part, for an addition to tax for the failure to file a required tax return or to pay any required tax, “unless it is shown that such failure is due to reasonable cause and not due to willful neglect[.]” Similarly, the pertinent part of
W.Va.Code,
ll-10-19(a) [1978] states that a tax penalty is due from any person required to account for and pay over any tax but “who willfully fails truthfully to account for and pay over such tax[.]”
In the present case the taxpayer challenged the tax assessments in good faith, and there has been a substantial legal controversy concerning the validity of the assessments. Accordingly, this Court holds that where, as here, a required tax return is not filed or a required tax is not paid due to a good-faith challenge to the validity of such requirement(s), the failure to file or to pay “is due to reasonable cause and not due to willful neglect,” and a court, upon an appeal of a tax assessment in such a case, should vacate the addition to tax or any tax penalty authorized by
W. Va. Code,
11-10-18 or -19, as amended, even if the
tax and interest portions of the tax assessment are affirmed.
See Pennsylvania & West Virginia Supply Corp. v. Rose,
179 W.Va. 317, 323, 368 S.E.2d 101, 107 (1988); syl. pt. 8,
United Fuel Gas Co. v. Battle,
153 W.Va. 222, 167 S.E.2d 890, and 153 W.Va. at 274-76, 167 S.E.2d at 918-20,
appeal dismissed and cert. denied,
396 U.S. 116, 90 S.Ct. 398, 24 L.Ed.2d 309 (1969).
V
CONCLUSION
For the reasons stated in sections II and III of this opinion, this Court reverses the final order of the circuit court to the extent that it vacated the tax and interest portions of the tax assessments. On the other hand, for the reasons stated in section IV of this opinion, we affirm the final order of the circuit court insofar as it vacated the additions to tax and tax penalties. We remand this case with directions for that court to modify its judgment in accordance with this opinion.
Reversed in part; affirmed in part; remanded with directions.