LAKE, Justice.
In Case No. 65, decided 10 May 1972, In Re McLean Trucking Co., 281 N.C. 242, 188 S.E. 2d 452, we have held that the tax situs of the interstate vehicles here in question is Winston Township. We affirm that decision.
All references herein to Chapter 105 of the General Statutes, both as to section numbers and as to content, relate to statutes in effect in 1970, not to the 1971 revision of the Machinery Act.
G.S. 105-294 provides:
“All property, real and personal, shall as far as practicable be appraised or valued at its true value in money. The intent and purpose of this section is to have all property and subjects of taxation appraised at their true and actual value in money, in such manner as such property and subjects of taxation are usually sold, but not by forced sale thereof; and the words ‘market value,’ ‘true value,’ or ‘cash value,’ whenever used in this chapter, shall be held to mean for (sic) the amount of cash or receivables in the property and subjects can be transmuted into when sold in such manner as such property and subjects are usually sold.”
[383]*383G.S. 105-327 (g) provides, with reference to the powers and duties of the County Board of Equalization and Review:
“(1) It shall be the duty of the board of equalization and review to equalize the valuation of all property in the county, to the end that such property shall be listed on the tax records at the valuation required by law; and said board shall correct the tax records for each township so that they will conform to the provisions of this subchapter.
* * *
“(3) The board * * * shall correct all errors in the names of persons, in the description of property, and in the assessment and valuation of any taxable property appearing on said lists; shall increase or reduce the assessed value of any property which in their opinion shall have been returned below or above the valuation required by law; and shall cause to be done whatever else shall be necessary to make said lists comply with the provisions of this subchapter. * * * ”
G.S. 105-275, with reference to the duties and powers of the State Board of Assessment, provides:
“Duties of the Board. — The State Board of Assessment shall exercise general and specific supervision over the valuation and taxation of property taxation (sic) throughout the State, including counties and municipalities. It is constituted * * * a State Board of Equalization and Review of valuation and taxation of property in this State. It shall be the duty of the Board:
“(3) To hear and adjudicate appeals from the boards of county commissioners and county boards of equalization and review as to property liable for taxation that has not been assessed or of property that has been fraudulently or improperly assessed through error or otherwise, to investigate the same, and if error, inequality, or fraud is found to exist, to take such proceedings and to make such orders as to correct the same.”
G.S. 143-318 provides, with reference to administrative proceedings before State agencies, such as the State Board of Assessment:
[384]*384“(1) Incompetent, irrelevant, immaterial, unduly repetitious, and hearsay evidence shall be excluded. The rules of evidence as applied in the superior and district court divisions of the General Court of Justice shall be followed.
íjs H»
“(3) Notice may be taken of judicially cognizable facts. * * * The agency’s experience, technical competence, and specialized knowledge may be utilized in the evaluation of the evidence.”
G.S. 143-315, with reference to judicial review of decisions of administrative agencies, such as the State Board of Assessment, provides:
“The court may affirm the decision of the agency or remand the case for further proceedings; or it may reverse or modify the decision if the substantive rights of the petitioners may have been prejudiced because the administrative findings, inferences, conclusions, or decisions are:
“(1) In violation of constitutional provisions; or
“(2) In excess of the statutory authority or jurisdiction of the agency; or
“ (3) Made upon unlawful procedure; or
“ (4) Affected by other error of law; or
“(5) Unsupported by competent, material, and substantial evidence in view of the entire record as submitted; or
“ (6) Arbitrary or capricious.
“If the court reverses or modifies the decision of the agency, the judge shall set out in writing, which writing shall become a part of the record, the reasons for such reversal or modification.”
The first step to be taken in this matter is to determine “the true value in money” of the tractors and trailers listed by McLean — 635 tractors, and 1,409 unassigned and 51 assigned trailers — as of 1 January 1970. G.S. 105-294. This is separate and apart from any question of an apportionment of such value.
The county tax appraisers valued the tractors in accordance with the Blue Book published by National Market Reports, [385]*385Inc. The Blue Book states one value for each tractor type and series, this being the publisher’s opinion as to the average retail value of the tractors in each such series. Taking the list filed by McLean, the county appraiser assigned to each tractor shown thereon the appropriate average value. The county followed this procedure in valuing all tractors listed for taxation in 1970, irrespective of whether the owner listed one tractor or many.
McLean offered the testimony of Mr. Phil Deans, Used Truck Manager of White Trucks, a division of White Motor Corporation. Mr. Deans classified the 635 tractors according to manufacturer, age and model number. He assigned a per unit value to each such group, giving to eight groups, containing a total of 408 tractors, a valuation within a range, the variation within each such range being either $250 or $500. The remaining four groups, containing 227 tractors, he assigned specific values per unit. Thus, he too assigned to the tractors average values.
McLean also introduced evidence of the book value of these tractors, using the same classification used by Mr. Deans. The book values of the respective groups varied substantially from the values assigned by Mr. Deans. For example: Mr. Deans valued 90 GMC 1963 tractors at $2,350 per unit, whereas the book value was $1,578 per unit, but Mr. Deans valued 179 White 1966 tractors at $4,500 to $5,000 per unit, whereas the book value was $6,462 per unit. Mr. Deans valued 125 White 1969 tractors at $11,000 per unit, whereas the book value was $13,499 per unit.
Mr. Deans testified that it has been his experience that the values stated in the Blue Book published by the National Market Reports, Inc., are substantially higher than the actual market values of such vehicles, and that in order to obtain a price approximating the value stated in the Blue Book, it is necessary to spend 20% to 25% thereof in reconditioning the truck. McLean describes the condition of all its vehicles as “good.”
The county, using the Blue Book value per unit, valued the 635 tractors at $6,295,810. McLean’s book value is $5,161,199.
There is no Blue Book for trailers. The county appraiser testified that he conferred with the sales manager at the local [386]*386office of the Fruehauf Company and with a dealer in new and used trailers. From the information so obtained, he arrived at the opinion that a new 45-foot trailer had a value of $8,000 and a new 40-foot trailer had a value of $7,000. To these figures he applied depreciation at the rate of 20% for the first year and at the rate of 10% of the preceding year’s value in each subsequent year. The depreciation rate so applied was based upon information given the appraiser by the above mentioned dealer. Upon this basis the county appaiser valued the 1,460 trailers, including 51 assigned to the Winston-Salem terminal, at $5,327,931. He used this method and these basic figures in appraising all trailers listed for taxation in Forsyth County in 1970, whether by McLean or by other taxpayers.
McLean offered evidence that in 1970 it purchased 225 new 45-foot tandem trailer units for an average cost of $6,104.81 per unit. These 1970 purchases were, of course, not included in the tax list in question. Upon cross-examination, it was developed that these purchases were in large blocks of not less than 60 units and McLean was given substantial price discounts due to volume. McLean further introduced in evidence its book value of its entire fleet of 2,918 trailers, the total being $8,714,122. The book value, of course, represents the price paid by McLean, less its computation of depreciation, and thus reflects similar volume discounts given McLean by its suppliers. McLean did not offer evidence of the book value of the 1,460 trailers involved in this proceeding. The State Board of Assessment simply assigned to these the proportionate part of the book value of the entire fleet.
McLean also offered the affidavit of Mr. Harrison, the local Factory Branch Manager of the Fruehauf Corporation, which was received without objection. Mr. Harrison stated that he is familiar with the various types of trailers included in the McLean fleet and, from time to time, has made appraisals for McLean. Classifying McLean’s entire fleet of 2,918 trailers, only 1,460 of which are involved in this appeal, into 30 groups according to manufacturer, age, type and length, he gave his opinion as to the average unit value in each group. McLean also introduced the affidavit of Robert L. Millikin, Branch Manager for Trailmobile, Inc., to the same general effect, though varying slightly as to the respective unit values of the several groups of trailers. There is nothing to indicate that either of these witnesses ever saw or appraised any one [387]*387of the 1,460 trailers involved in this appeal and there is no evidence showing that the 1,409 unassigned trailers which move in and out of North Carolina and which are involved in this appeal, fall proportionately into each of the 30 groups or classifications into which these two witnesses divided McLean’s entire fleet.
The County Board of Equalization and Review affirmed the tax appraiser’s valuation of the 1,409 unassigned trailers at $5,141,569. The State Board of Assessment reduced this to $4,207,178, using McLean’s book value as its measure.
G.S. 105-294, quoted above, requires that tractors and trailers, like other property, be appraised for purposes of taxation at their “true value in moneyi.e., their sale value. A tractor or trailer which is part of a large fleet does not, for that reason, have a different sale value from that which it would have if it were the only tractor or trailer owned by the taxpayer. The appraisal of property for taxation cannot be made to depend upon the number of units of similar properties owned by the taxpayer or upon the varying abilities of the several taxpayers to negotiate for favorable terms in buying or selling such units. To hold otherwise would depart from the principle of equality of appraisal which is fundamental in the Machinery Act. In accepting McLean’s book value of its tractors and trailers as the “true value in money” of these properties, the State Board of Assessment erred, since the book value is based upon what McLean actually paid for the vehicles and, therefore, reflects McLean’s peculiar purchasing power due to the size of its fleet and the resulting volume of its purchases. See, Annot., 160 A.L.R. 684, 686.
The use of the Blue Book published by National Market Reports, Inc., in the valuation of trucks (tractors) for taxation has been approved by this Court. In re Block Company, 270 N.C. 765, 155 S.E. 2d 263. In that case he replied, at least in part, upon G.S. 105-428, which statute, by its terms, had no application to Forsyth County. It was repealed in 1971. We do not construe the omission of Forsyth from the list of counties to which G.S. 105-428 was made applicable as a prohibition against the use of the Blue Book for such purpose in Forsyth County. As we said in the Block Company case, at page 769:
“The task of examining and appraising each of the thousands of trucks and cars in [Forsyth] County would [388]*388be almost impossible. To avoid this, the County is justified in using some recognized dependable and uniform method of valuing them. There is no ‘the’ Blue Book nor a ‘the’ Red Book, any more than there is a ‘the’ Almanac, but the authorities may use this type publication as a guide, and in the absence of merited complaint adopt figures given by the publication as valuations which would be subject to the assessment ratio. But we know that not all 1964 Buicks, for instance, are of the same value. One may have been driven 200,000 miles and be almost worn out while another had been carefully driven for only 6,000 or 8,000 miles. One may be wrecked and damaged almost to the extent of uselessness, in which event the taxpayer would be entitled to some consideration. And the owner making such a showing should not be taxed upon the arbitrary valuation placed in a publication giving no consideration to the condition of the article.” (Emphasis added.)
Obviously, the Blue Book figure is an estimate as to the value of the average vehicle in the designated class. Its reliability increases, however, when used as a guide to the value of the units in a large fleet of vehicles, such as that here in question. The use of such a publication and its uniform application to all such vehicles listed by all taxpayers in the county cannot be deemed arbitrary per se. As suggested in the appeal of the Block Company, supra, the burden is upon the complaining taxpayer to show that the application of such standard to his vehicles results in their being appraised at a figure in excess of their market value. G.S. 143-318 does not apply to county authorities. The Blue Book was introduced without objection at the State Board hearing. Furthermore, it is within an exception to the Hearsay Rule. See, Stansbury, N. C. Evidence, 2d Ed., § 165.
The State Board of Assessment found that used tractors will not sell for the Blue Book value unless they have been reconditioned at a cost of approximately 20% to 25% of that value. This is in accord with the testimony of Mr. Deans. However, 75% of the Blue Book value of these 635 tractors is $4,721,857, whereas Mr. Deans’ estimate of the value of these vehicles, using the upper limits of his several value ranges, was only $3,314,250. The book value of these vehicles was $5,161,199, and the board concluded that the book value is the best indication of fair market value in this case. The State Board of [389]*389Assessment never actually found the fair market value of the 635 tractors. However, we interpret its statement concerning book value as a finding that such fair market value of the 635 tractors was $5,161,199. We hold that such finding is “unsupported by competent, material, and substantial evidence in view of the entire record as submitted.”
For the reasons above mentioned, the book value of the trailers is not the measure of their fair market value. Also, McLean’s evidence that in 1970 (after the listing in question) it purchasesd 225 new 45-foot trailer units for an average price of $6,104.81 is not indicative of the sale price of a new 45-foot tandem trailer. The record shows these purchases were made in large blocks from the same dealer, so that the price reflects a substantial volume discount. Thus, the evidence does not show the county’s appraisal based upon its information as to the selling price, new, of such trailers resulted in an excessive valuation. The testimony of Witness Harrison that Fruehauf advertises a 40-foot trailer for $4,495 does not tend to refute the county’s valuation for the reason that this witness stated the trailer so advertised is not of the same quality as those used by McLean.
On the other hand, there was no competent evidence before the State Board of Assessment supporting the county’s appraisal of these trailers. The evidence for the county and city consisted of the testimony of two of the county’s tax appraisers. Both testified that their appraisal was based upon information as to the price of trailers, new, obtained by them from an official of the Fruehauf Corporation and from a dealer in trailers. Neither the official of Fruehauf Corporation nor the dealer was called as a witness. Neither witness for the county and city purported to have basis for an opinion of his own as to the market value of the trailers, new or used. Neither made an inspection of any of the vehicles in question.
This is not to say that there was an impropriety in their making their original appraisals on the basis of information so obtained. Such appraisals are not required to be based upon evidence competent in a judicial proceeding. However, in a proceeding before the State Board of Assessment upon an appeal from the action of the county taxing authorities, G.S. 143-318 governs the admissibility of evidence. It provides that the rules [390]*390of evidence as applied in the superior and district court divisions of the General Court of Justice shall be followed. While the testimony of these witnesses was competent to show the method they used in reaching their appraisal of trailers (those of McLean’s and those of other taxpayers alike), it was not competent on the question of the correctness of those appraisals. It was hearsay and does not fall within any exception to the hearsay rule.
There was no competent evidence before the State Board of Assessment as to the “true value in money” of the McLean trailers, except the testimony of Messrs. Harrison and Millikin, witnesses for McLean, each of whom valued McLean’s entire fleet of 2,918 trailers far below the book value thereof, which the board found to be the entire fleet’s true value in money.
We hold, therefore, that the superior court erred in its Conclusion No. 1 that the findings of fact and conclusions of law made by the State Board of Assessment respecting the fair market or true value of the equipment in question are supported by competent and material evidence.
The State Board of Assessment actually made no finding as to the “true value in money” of the 635 tractors which travel in and out of North Carolina. It valued McLean’s entire fleet of 1,166 tractors at the book value thereof, $8,884,945, and valued the 1,409 trailers, unassigned by McLean to any terminal, at their book value, $4,207,178. It then attributed 9.62% of each of these amounts to Forsyth County as the tax value of the portion of McLean’s interstate vehicles attributable to Forsyth County.
Nothing else appearing, tangible personal property may be taxed at its full value by the state of the owner’s domicile even though it is frequently taken or sent out of such state during the tax year. New York Central Railroad Co. v. Miller, 202 U.S. 584, 26 S.Ct. 714, 50 L.Ed. 1155. The state of the domicile may determine how the taxable value of property, subject to its taxing jurisdiction, shall be allocated among its several counties. With exceptions not here material, this State has determined that the tangible personal property of a domestic corporation shall be listed for taxation at its true value in money in the county and township wherein the principal office of the corporation is located. G.S. 105-302 (a); In re McLean [391]*391Trucking Co., supra. In the absence of legislative authority, the value of tangible personal property, subject to the taxing power of this State, may not be apportioned between such county and any other taxing unit in or out of North Carolina. In re Freight Carriers, 263 N.C. 345, 139 S.E. 2d 633. The Machinery Act of 1971 makes certain provisions for the allocation or apportionment of the valuation of properties of truck companies for tax purposes, but those provisions did not become effective until 1 January 1972 and, consequently, have no bearing upon this appeal. G.S. 105-395. For the tax year 1970, there was no statutory authority in this State for the allocation or apportionment of the value of McLean’s vehicles as between Forsyth County and other taxing units in or out of this State.
The failure of the Legislature to provide for constitutionally required apportionment of the tax valuation of property between this and other states cannot, of course, enlarge the taxing jurisdiction of this State or of its counties. Obviously, Forsyth County may not tax McLean upon property which is beyond the taxing jurisdiction of North Carolina. On the other hand, this State’s jurisdiction to tax a domestic corporation upon property which is outside, its borders during part or all of the tax year does not depend upon what other states do, in fact, with reference to imposing taxes upon the corporation on account of such property. A tax improperly imposed by another state cannot deprive this State of taxing jurisdiction, nor does the election of another state not to tax that which is within its taxing power confer upon North Carolina authority to tax that which it could not otherwise tax. Central Railroad Company of Pennsylvania v. Pennsylvania, 370 U.S. 607, 613, 82 S.Ct. 1297, 8 L.Ed. 2d 720, reh. den., 371 U.S. 856, 83 S.Ct. 15, 9 L.Ed. 2d 93; Northwest Airlines v. Minnesota, 322 U.S. 292, 64 S.Ct. 950, 88 L.Ed. 1283.
It is now well settled that a state may not tax a domestic corporation on account of tangible personal property which is permanently located in another state. Union Refrigerator Transit Co. v. Kentucky, 199 U.S. 194, 26 S.Ct. 36, 50 L.Ed. 150. Likewise, the domiciliary state may not tax its domestic corporation on account of property which is habitually located and used in the business of the corporation in another state, even though such property may occasionally come into the state of the domicile. Central Railroad Company of Pennsylvania v. Pennsylvania, supra. On the basis of these principles, McLean [392]*392has not listed in Forsyth County its Group I tractors or its Class A trailers (for a description of these vehicles, see In re McLean, supra). The county and city do not here contend that those vehicles should have been listed for taxation by them. Thus, they are not involved in this appeal and we are not presently required to determine the correctness of such conclusion as to those vehicles.
The question of apportionment, assuming it to be applicable to any of the McLean vehicles, relates only to the vehicles which run in and out of North Carolina in the course of McLean’s business; that is, its Class II tractors and its Class B trailers. Only the value of these vehicles would be subject to apportionment and, assuming that the ratio of miles traveled in North Carolina to total miles traveled is the appropriate allocation factor, the mileage to be used in computing that factor would be the mileage accumulated by these vehicles only. Thus, the State Board of Assessment erred in allocating the value of all of McLean’s tractors between North Carolina and other states, since that figure included the value placed upon vehicles totally beyond the taxing jurisdiction of North Carolina. It also erred in using as the allocation factor the ratio of miles traveled in North Carolina to the total miles traveled by all of McLean’s interstate vehicles, since the latter figure included the miles traveled by vehicles not taxable in North Carolina because they never, or only rarely, come into this State.
We conclude, however, that upon this record the question of apportionment of Class II tractors and Class B trailers (the vehicles' which operate in interstate commerce' in and out of North Carolina) does not arise at all. Billings Transfer Co. v. Davidson, supra. In the Billings Case, we said, at page 34, “The burden is on the taxpayer who contends that some portion of his tangible personal property is not within the taxing jurisdiction of his domiciliary state to prove that the same property has acquired a tax situs in another jurisdiction.” We also said in the Billings Case, at page 34, “With respect to tangible movable property, a mere general showing of its continuous use in other states is insufficient to exclude the taxing power of the state of domicile,” and, at page 33, “When a fleet of vehicles is operated into, through, and out of a nondomiciliary state, a Tax situs’ sufficient to satisfy constitutional requirements is acquired if (a) the vehicles are operated along fixed routes and [393]*393on regular schedules, or (b) the vehicles are habitually situated and employed within the nondomiciliary jurisdiction throughout the tax year.” The record before us does not show that Class II tractors and Class B trailers are habitually situated and employed in any other state throughout the tax year. Nor does the record show that these vehicles are operated on regular schedules. McLean’s Witness Wells testified:
“The period of frequency and the time within which trailers might leave a designated terminal to another could vary depending on the volume of traffic. So when you speak of timetables, there are no timetables on an hour or minute basis. There are timetables on a daily basis.
“I would say that with respect to schedules and the number of trailers at a particular terminal, it would depend on the demand and need that are dictated by the volume of business.”
McLean’s Witness Elkins testified:
“A typical example of our operation — a truck, at least one or more trucks, would be dispatched to Boston, Massachusetts, [apparently from Winston-Salem] every day and when they arrive in Boston, Massachusetts, they do not remain there as permanent fixtures. They come back out to various other places. I am referring to interstate equipment. It is conceivable that after this equipment arrives in Boston, it might not return to Boston for some months.”
Thus, any specific tractor or trailer has no fixed, regular route or schedule. It moves from one terminal to another as the current volume of business requires. The total number of vehicles moving to or from any specific terminal varies from day to day as the volume of business fluctuates. This does not establish a tax situs for these vehicles in any other state in accordance with the rule of Billings Transfer Company v. Davidson, supra. Therefore, for the year 1970, McLean was taxable in Forsyth County upon the full value of the 635 Class II tractors and the 1,409 Class B trailers. The State Board of Assessment erred in allocating to Forsyth County only a portion of the value of these vehicles and the superior court erred in remanding the matter to the State Board of Assessment for further consideration with regard to the question of apportionment. The matter must, however, be remanded [394]*394to the State Board of Assessment for further consideration and determination of the value as of 1 January 1970 of the properties of McLean here in question after due notice to all parties to this proceeding and an opportunity to them to present such evidence upon the question of valuation as may he competent under G.S. 143-318.
The judgment of the superior court must, therefore, he modified and to that end this matter is remanded to that court for the entry of a judgment by it which shall:
1. Affirm the final decision of the State Board of Assessment insofar as it finds, concludes and orders' that the proper tax situs of the vehicles in question for the year 1970 is Winston Township;
2. Vacate and set aside the decision of the State Board of Assessment insofar as it purports to determine and fix the value, for the purposes of taxation by Forsyth County for the year 1970, of the properties of McLean here in question;
3. Vacate and set aside the decision of the State Board of Assessment insofar as it orders McLean to list in counties of North Carolina, other than Forsyth County, the properties of McLean specified in the said decision of the State Board of Assessment; and
4. Remand this matter to the State Board of Assessment for the determination by it of the true value in money, as of 1 January 1970, of the 635 tractors, the 1,409 unassigned trailers and the 51 assigned trailers to which this proceeding relates, and the allocation by it to Forsyth County of the entire value of such properties, for the purpose of taxation for the year 1970, such determination to be made by the State Board of Assessment following a further hearing by it, of which hearing all parties to this proceeding shall be given due notice and at which hearing they may offer evidence competent under G.S. 143-318.
Error and remanded.