delivered the opinion of the Court.
Plaintiffs in error commenced action against the Board of County Commissioners of El Paso county to recover the entire amount of 1952 taxes levied on two separate parcels of their real estate situated in Colorado Springs, and paid by them under protest.
By their complaint plaintiffs allege that the tax assessment for the year 1952, while purporting to be that of the county assessor, actually was made by the Colorado Tax Commission (hereinafter referred to as Tax Commission, or Commission) pursuant to its state-wide *434reappraisal program, and that said assessment was imposed upon said assessor by the Commission by forcing that official to prepare 'an inventory of all buildings and property within his county, upon forms provided by the Commission, the valuations of said improvements to be fixed in accordance with a “Tax Manual,” or pricing manual, likewise furnished by the Commission, said completed inventory, with the values determined as stated, being referred to as “Building Description and Value Calculation” to be thereafter used as the basis for assessment as to all said properties. It further is alleged that all such valuations determined in accordance with said manual were based upon 1941 cost of reproduction; instead of present market value. Finally it is alleged that the assessment for 1952, made as outlined in plaintiffs’ complaint, is violative of section 8 of Article XIV of the Constitution of Colorado, and, therefore, is illegal and void, and that the acts of the Commission of which complaint is made, are without and beyond its authority and are contrary to law and of no legal effect.
The Tax Commission, appearing by the Attorney General, and the Attorney General, pro se, were granted leave to intervene, and joined the Board of Commissioners in answer to plaintiffs’ complaint. By the answer it is admitted that the 1952 assessment was made pursuant to the general reappraisal program directed by the Tax Commission; that the documents referred to in the plaintiffs’ complaint as 'having been transmitted to the assessor by the Tax Commission were so furnished and supplied; that said assessor was directed to make use of the same in determining the valuation of taxable property within his county, but it is denied that the acts of said Tax Commission in connection with said reappraisal, or the valuation of property thereunder, were, or that the assessment is, illegal in any respect; denied that the assessment was made by the Tax Commission; and affirmatively it is alleged that the same was made by the duly elected, qualified and acting assessor of said *435El Paso county; that all of the acts done by said assessor were required of him by law and were performed by him in pursuance of his duty as such officer. Following the specific admissions, denials and affirmative allegations by way of denial, is a general denial of “each and every allegation of the complaint not * * * specifically admitted or denied.” Then follows a second separate defense attacking the sufficiency of the complaint, and third and fourth separate defenses pleading failure on the part of plaintiffs to avail themselves of various 'administrative remedies, thus barring them from recovery.
The evidence consists only of the documents furnished the assessor by the Tax Commission; the orders, minutes and resolutions of the Commission; plaintiffs’ tax schedule; abstract of assessment, to which is appended the affidavit of the assessor verifying the assessment roll; and receipts for the payment of the tax under protest, all of which exhibits were admitted in evidence without objection, save as to their materiality. Only one witness was orally examined, and her testimony goes exclusively to an explanation of the manner in which the valuation index was compiled by use of the tax manual.
The trial court entered findings in effect that plaintiffs were the owners of the properties; that their 1951 valuation was $14,400, on which they paid a tax of $943.78; that the 1952 valuation was $34,930, on which they paid, under protest, a tax of $1,545.65; that the assessor of El Paso county, in fixing the valuation for 1952, caused a field inspection and appraisal of said premises to be made and “fixed the valuation thereon by applying to said field appraisal, the formulae set forth in the pricing manual and chart card furnished to the Assessor by the Colorado Tax Commission in pursuance of the state’s reappraisal program”; that said assessor used the same method for determining valuations of all property in said county and did not discriminate against plaintiffs or their property; that said assessor made use of said formulae and pricing manuals “of his *436own volition and without coercion or usurpation by the” Tax Commission; that proper notices of time and place for correction of errors by the assessor and by the Board of Equalization were given; but that plaintiffs failed to appear; nor did they make complaint to the Tax Commission nor to the State Board of Equalization; nor avail themselves of any administrative remedy whatsoever. The trial court specifically found, “that the said reappraisal program of the State of Colorado and the statutes authorizing the same, do not violate, or offend, the Constitution of the State of Colorado and particularly section 8 of Article XIV thereof.” Pursuant to the foregoing findings the court determined that the complaint failed to state a claim upon which relief could be granted and entered judgment against the plaintiffs.
At the outset, counsel for plaintiffs, emphasizing the fact that it is not the intention to claim a refund of 'any part of the tax paid, but insistence on the part of plaintiffs that the entire tax is illegal and void, voluntarily removes them from any relief that might have been afforded under the administrative procedures provided by statute. They insist that if their action is maintainable at all, it is pursuant to the provisions of C.R.S. ’53, 137-1-22. Other points alleged by plaintiffs to be1 erroneous in the findings and conclusions of the trial court are:
(1) That the finding of the court that the assessor made use of the formulae and pricing manuals provided by the Commission as of his own volition, without coercion by the Commission, is unwarranted.
(2) That the trial court erred in finding that the reappraisal program, and the statutes authorizing the same, do not violate the Constitution of the State of Colorado and particularly section 8 of Article XIV thereof.
(3) That the Tax Commission violated section 8 of Article XIV of the Colorado Constitution by substituting its assessment for that which should have been made by the county assessor; and
*437(4) That said, assessment is based upon reproduction value rather than market value and therefor is contrary to law.
At the outset counsel for plaintiffs was confronted with a dilemma in determining the form of his attack. His difficulty in this respect was first presented when he drew his pleadings; again when the case was heard by the trial court; and it pursues him likewise upon this review. If he admits the constitutionality of the statute and asserts that injury resulted to his client only by reason of the improper application and administration of valid law, then his complaint falls into that class of proceeding where the tax may be said to be irregular, improper or erroneous, making recourse* to the courts conditional upon his first having exhausted the usual administrative remedies. In such case the tax could not be said to have been illegally laid but erroneously computed, thus bringing the issues squarely within the rule announced in Bordner v. Board of County Commissioners, 92 Colo. 81, 18 P. (2d) 323; Miller v. Board of County Commissioners, 92 Colo. 425, 21 P. (2d) 714, and other decisions of this Court cited in Citizens’ Committee v. Warner, 127 Colo. 121, 136, 254 P. (2d) 1005, wherein the Miller and Bordner cases were given approval.
Plaintiffs’ approach would seem to be somewhat double-barrelled in that it is contended that if the statute is not unconstitutional and invalid, the proceedings conducted pursuant thereto were irregular and illegal. This lends merit to the separate defenses interposed on behalf of defendants to take advantage of the fact that the administrative remedies provided by various statutes had not been pursued; and, in the light of such defenses, also warrants the special findings of the trial court that plaintiffs had failed to pursue said administrative remedies, to which findings plaintiffs now object on the ground that they are immaterial and irrelevant to any issue in the case. It could well be that the case might be disposed of upon this issue alone, but we hesi*438tate to pursue that theory to its extremity in view of the insistence of plaintiffs’ counsel that his entire case is based upon the invalidity of the law and his admission that, unless he has an action maintainable under C.R.S. ’53, 137-1-22, the proceeding must fail in its entirety.
In passing, attention should be called to the well-established rule that where one attempts to maintain a proceeding for 'a tax refund pursuant to the statute above cited, he has the burden of showing that the tax was illegally laid, is erroneous in its entirety, and incapable of adjustment. If the property be assessed too high, or illegally assessed because of error capable of adjustment, then the administrative remedies must be pursued. Northcutt v. Burton, Assessor, 127 Colo. 145, 152, 254 P. (2d) 1013.
It also is important to bear in mind the general rule that “every statute, duly passed, must be declared constitutional unless the contrary appear beyond a reasonable doubt.” Watrous, State Highway Engineer v. Golden Chamber of Commerce, 121 Colo. 521, 547, 218 P. (2d) 498.
The acts of the Tax Commission of which complaint is made, and its authority therefor, are to be measured by the provisions of C.R.S. ’53, 137-6-12, which grants to said Commission authority over the general administration and enforcement of all laws pertaining to the assessment and levy of taxes, directing that, it “shall exercise supervision over the county assessors, boards of county commissioners, county board of equalization, and all other officers and boards of assessment and levy, to the end that all assessment of property, real, personal, and mixed, be made relatively just and uniform and at its true and full cash value; to require all county assessors * * * to assess all property of every kind or character at its actual and full cash value.” The Commission also is authorized to prepare and transmit to the assessors, “such instructions as it deems conducive to the best interests of the state upon any subject affecting *439taxation, * * *. It shall see that all laws concerning the valuation and assessment of all classes of property are faithfully obeyed. It shall issue such orders and instructions to the different taxing officers as will carry into effect the provisions of law relating to taxation and shall enforce the same agreeably to the provisions of this chapter.” The various officers are required to forward to the Commission such records and information “as are deemed necessary by the Commission to properly and effectually -carry into operation the provisions of this chapter.” The Commission also is directed to investigate the works and methods of the -county assessors and other officers in order to bring about the equalization of taxes on all kinds of property. The foregoing would seem to cover the general duties and obligations of the Tax Commission.
That said general objective may be accomplished, specific authorization is granted the Commission, by subdivision (6) -of said section, to make reap-praisement, the portion thereof pertinent to this case reading as follows:
“Whenever in the judgment of the tax commission property in any county or municipal subdivision thereof has not been assessed at its true and full cash value the Commission may make a re-appraisement of the property therein, to the -end that all classes of property in such taxing district shall be assessed in compliance with the law. When a reappraisement is ordered in any taxing district the commission shall appoint an appraiser, and assistant appraisers if necessary, who shall forthwith proceed to appraise such property in such taxing district, and who shall have all the powers, shall perform all the duties pertaining to the appraisement -of property and shall receive the same compensation from the same sources as provided by law for assessors of real or personal property, as the -case may be. * * * ”
Here again plaintiffs fire with both barrels. They contend: (1) That the statute itself is unconstitutional *440because it permits an intrusion upon the duties of the county assessor as a constitutional officer; and (2) that if said statute be cleared of such charge, then the actions of the Commission in attempted- pursuance thereof are violative of the Constitution.
With respect to the first contention counsel’s argument closely parallels that of the plaintiff in error in Ames, County Assessor v. People, ex rel., 26 Colo. 83, 92, 56 Pac. 656, wherein was involved an attack upon -a statute authorizing the then State Board of Equalization to determine the assessment of railroads for taxation purposes. The objection there, as in the instant case, was that the statute conflicted with section 8 of article XIV of the Constitution of the State of Colorado. Said section, with reference to the assessor, simply provides that “There shall be elected in each county * * * ; one county assessor;” who shall be paid as may be provided by law. His duties are not prescribed, and, as in the Ames case, it is contended that it is to be conclusively presumed -that the duties of the assessor are such as ordinarily are -attached to that office at common law. Because thereof, it further is contended, as likewise in the Ames case, supra, that the legislature is forbidden to authorize any other officer, or board, to assess any class of property and that the only officer of the state qualified under the law to make any assessment is the county assessor.
The decision in the Ames case, supra, bars the door against any such narrow construction as that contended for by counsel in the instant case. In that case this Court specifically held that, while the office of assessor is stipulated by the Constitution, the legislature is not inhibited from passing a law placing the fixing of valuation for assessment of certain properties under 'another authority, and generally, that control of matters of taxation is plenary to the legislative branch of the government, unless restricted by some constitutional provision. The section of the Constitution under discussion *441is not such a limitation, and the 'assessor is not thereby clothed with the sole authority of assessing property.
The rule in the Ames case was approved, broadened, and as so extended, applied in the case of People, ex rel. Colorado Tax Commission v. Pitcher, 56 Colo. 343, 138 Pac. 509, wherein the court had under consideration the original legislation constituting the Tax Commission and granting said Commission jurisdiction over, and power and authority to supervise and direct, the actions of assessors and the assessment of all taxable property in the State of Colorado for ad valorem levy. The Act has since been amended and is herein-above cited as C.R.S. ’53, 137-6-12, but no amendment thereto since the decision in the Pitcher case, supra, has changed the fundamental principles therein considered. In that case the constitutionality of the Act now under discussion was firmly established, and it was made definitely certain that, “The legislature may adopt a pl'an whereby the work of assessors may be corrected, supplemented, added to or changed.” It was specifically declared that:
“So here, we decline to hold how far the general assembly may go in that respect. Nevertheless, in view of the constitutional provisions hereinbefore mentioned and to which reference will again be made, we are certain the legislature may adopt a plan whereby the work of assessors may be corrected, supplemented, added to or changed. Thereby that which the assessors were previously authorized to do by law need not be taken 'away, but those agencies may still be left free to perform those functions.”
We adhered to this principle in People ex rel. v. Pitcher, 61 Colo. 149, 167, 156 Pac. 812, wherein it was specifically stated that, “The office of County Assessor in each county was created by the Constitution, but the duties thereof were prescribed by legislative acts.” It also was held that the Tax Commission has authority to make original assessment of certain classes of property *442and can require the proper officials to make like assessments of all other property.
It, therefore, is clear that the constitutionality of the statutes pursuant to which the tax commission functions have been established not only with respect to section 8 of article XIV, but likewise as to various other constitutional objections raised in the cases cited, supra. With respect to the statute itself there can be no present question as to its constitutionality. However, counsel for plaintiffs contends that even if the statute be declared constitutional, the acts of the Commission pursuant thereto were exercised in an unconstitutional manner, in that the statute does not authorize the Commission to establish standards by which the assessor is required to determine valuations of taxable property. It is insisted that the authority of the Commission is limited only to a change in property valuations first made by the assessor. This position is unrealistic and is entirely too narrow in scope, as we shall undertake to demonstrate.
Fundamentally, in the necessity of obtaining public funds through taxation for the purpose of operating the government, valuations fixed on taxable property are within themselves, of no particular moment. The basic principle of taxation is not valuation, but equalization. From the very beginning of state government, stress h'as been placed upon equalization in the contribution of taxes levied for governmental use. The whole of Article X of the Colorado Constitution relates to revenue and taxation. Section 3 thereof provides that:
“All taxes shall be uniform upon the same class of subjects within the territorial limits of the authority levying the tax, and shall be levied and collected under general l'aws, which shall prescribe such regulations as shall secure a just valuation for taxation of all property, real and personal; * *
Numerous statutes have been passed at various times directing that all property shall be 'assessed at its full *443cash value. These words are emphasized by repetition in C.R.S. ’53, 137-6-12.
No doubt attainment of one hundred per cent equalization in the burden of taxation is beyond hope of full realization because of the necessity of dependence upon human agencies. In attempts to solve the problem, or 'at best to attain a higher degree of perfection, numerous efforts have been made to implement the procedures of taxation. The most effective approach yet developed has been to grant to the Tax Commission general supervisory authority over all of the officers and boards having to do with the assessment of property for taxation, including the specific authority to make reappraisement of all property within any one or more of the counties or subdivisions of the state wherein property has not been assessed at its true and full cash value. By the statute, such appraisers are given equal authority with county assessors.
It is self-evident that in order to determine whether every subdivision of the state has assessed all property therein at its full and true cash value, the Tax Commission must of necessity fix and establish certain standards by which these various assessments and valuations are to be judged. No objection is made to the fixing of standards for that purpose. Why, then, should objection be raised to the establishment of standards so as to procure and bring about reasonably equal and equitable assessment in the first instance? If standards are necessary and advisable in determination of equality that the Commission may order correction, there is no logical re'ason why they should be considered as less beneficial, in the interest of good government, when applied as guides to procure more equitable original assessments. Adoption of the negative view would be to apply precaution at the wrong end of the transaction; to do so would condemn the locking of the door before the horse is stolen while commending similar precaution afterwards. In our view, the statute is sufficiently broad *444to fully justify the Commission in the adoption and application of reasonable standards essential to bring about a more accurate, equitable and equal original assessment.
Counsel further objects, however, to the methods of the Commission by insisting that its direction to the county assessor in El Paso county was a usurpation of his authority and the dictation of its judgment of property values rather than leaving such to the assessor. The record in this case does not bear out such contention. It is true that the Commission issued a pricing manual and various other data and forms which the assessor was directed to use, but these were designed only for the aid and assistance of the assessor and as standards by which he could more accurately appraise the property under his jurisdiction. In effect these directives simply gave the technical steps necessary to make an accurate valuation appraisal. They contain every possible situation that one can think of that could confront an assessor or appraiser in determining a fair valuation, including not only types of buildings, but also depreciation, obsolescence, locality, proximity to lower-class construction, and all manner of things which should enable a competent appraiser to determine a real and fair evaluation rather than a mere estimate or guess. The assessors were directed to make assessment at full cash value. The materials furnished them, according to the order of the Commission, were “to implement assessment procedures by prescribing standards of assessment and methods and forms.” This was the extent of the dictation. The assessment actually was made by the assessor and the officers under his supervision and 'direction, by and with the assistance of representatives from the Tax Commission’s office. The abstract was certified by the assessor himself. The trial court found that the assessor made the assessment and his findings are fully supported by the evidence.
By answer, and during the course of trial, defendants admitted that the Tax Commission furnished the assessor with the pricing manual, forms for the inventory *445of property, and for determination of reproduction cost at 'a certain period, and that said Commission likewise sent its representatives to assist the assessor in the completion of said inventory and to check his work with respect thereto. It is contended on behalf of plaintiffs that defendants likewise admitted that, by insisting upon the assessor complying with the directives of the Commission, said Commission usurped the authority of the assessor, coerced him into certifying an assessment not made by him, and that the resulting assessment actually was dictated and made by the Commision itself. In this latter contention the plaintiffs are clearly in error as a study of the pleadings, rather fully outlined at the beginning of this opinion, makes it very clear that the defendants definitely deny all acts of coercion and insist that the assessment actually was made by the assessor pursuant to the formulae and suggestions of the Commission. It also is insisted that the Commission had the right to demand these things. This phase of the issue already has been discussed and determined adversely to plaintiffs.
Lastly, it is urged that the assessment was required by the Commission to be made upon reproduction cost rather than market value. Here again plaintiffs are in error for the reason that the documents offered as exhibits, and relied upon in support of this contention, demonstrate that the Commission desired to make use of the selected reproduction cost only as a basis, guide, or standard for the determination of full cash value. Also, that its communication of this desire to the assessors was not in the nature of an order but as a suggestion. Exhibit L is entitled, “Suggestions to Assessors for Establishing ‘Full Cash Value’ on Real Estate:” The first paragraph reads: “A roll back of present day values to those in effect in the year 1941 will, in our opinion, comply with the laws requiring full cash value.”
Exhibit C, the appraisal manual, is not claimed by the Commission to be complete and it invites suggestions *446from, the assessors by way of improvement. Exhibit D, the pricing manual, is a compilation of scientific cost statistics. Exhibit B contains instructions on the procedure of pricing and determining values. It sets forth various forms and procedures for the appraisal of property and then in section F treats the important phase of reproduction cost appraisal as an element in determination of uniform property classification. Therein the Commission calls to attention that “In order to arrive at a relatively correct final appraised value, it may be necessary to consult the cost of production of properties, market or sales values, income, rentals, and related information. In the majority of cases reproduction cost alone may be sufficient indication of relative value among properties, and is the first approach to the determination of final value for assessment appraisal.” It then directs that from this figure so determined, there shall be deducted allowance for loss of value by reason of age, depreciation, and obsolescence, including in the latter, “losses in value may be by reason of mis-placement of improvements in certain locations; * * * changes in the character of certain neighborhoods due to changes in population, land use, occupancy or shifts in business, lessened demands for certain groups or types of commercial buildings, resulting in the failure of specific buildings or groups of buildings to earn a fair minimum return on their investment; and changes in building design.” Then follows the admonition that "“final procedure in the handling of the calculations is the checking process, which should be assigned by the assessor to himself or to a trusted deputy.” A number of items then are set forth which the assessor should be careful to check.
It is manifest that the sole purpose on the part of the Commission was to furnish standards by which the assessor might be guided, to aid and assist him in arriving at a complete equalization of all the property within his county for taxation purposes, and also to *447procure an equalized value of similar properties located wxthin the several counties of the state, that taxation throughout the state might be on a uniform basis as the law requires.
The finding by the trial court that the assessment was made by the assessor of El Paso county is fully supported by the record, and observing no error in the proceedings of the trial court, its judgment is affirmed.
Mr. Justice Holland dissents.