FERREN, Associate Judge:

Appellant Wolf and other general partners of MidCity Investment Company appeal from a decision of the Tax Division of the Superior Court denying their petition for a partial refund of real property taxes for tax year 1986. Appellants own the office building located at 1001 Connecticut Avenue, Northwest, on the corner of K Street (above the Farragut North Metro station). They maintain that the trial court (1) erred in concluding that the District conducted an independent assessment for tax year 1986 when, as appellants see it, the District simply reiterated its proposed 1985 assessment; (2) erred in upholding the District's comparable sales and income valuation methods, since the District's calculations failed to consider the actual leasing and financing arrangements encumbering this and other comparable properties; and (3) erred in approving the District's initial 1986 tax assessment after the District, at trial, "abandoned" that initial assessment in an attempt to prove the building was worth more. Finding no errors, we affirm.

I.

The office building at 1001 Connecticut Avenue, N.W., built in the 1950s and never renovated, is located at one of the best commercial sites in the city. In tax year 1985, the District's proposed assessment was $14,620,500, of which $9,149,400 was allocated to land and $5,471,100 was allocated to the building and other improvements. Upon appeal to the Board of Equalization and Review (the Board), the proposed 1985 assessment was reduced to $13,539,022.

For tax year 1986, the parcel was assessed at the same value as it was for 1985: $14,620,500, with $9,149,400 allocated to land and $5,471,100 allocated to building and other improvements. Unlike the previous year, the Board affirmed the proposed 1986 assessment. Appellants paid the tax and filed a timely petition for refund in Superior Court, alleging that the proper assessment should be $10,356,360, the building's assessed value in tax year 1984. Before trial, the District amended its answer to say that the proper valuation of the property, including the building and other improvements, was $17,830,000.

During the two day trial, both Robert L. Klugel, Chief of the Real Property Tax Section of the District of Columbia Department of Finance and Revenue, and Troy Davis, the District's line assessor, testified regarding the methods they used to determine the total value of 1001 Connecticut Avenue. Both witnesses considered two of the three accepted procedures for valuation; the "comparable sales approach," i.e., comparing recent sales of properties similar to 1001 Connecticut Avenue, see 9 DCMR § 307.3 (1986), and the "income approach," i.e., using statutory guidelines to determine the amount an investor would be willing to pay to receive the future income stream that the property is expected yield, see id. § 307.5. After calculating the total value of the property, the assessors obtained the estimated value of the building by using the standard "building residual" method under which they subtracted the land value, $9,149,400, from the total value, $14,620,500, to arrive at a figure of $5,671,100 for improvements.

Klugel also testified that for tax year 1986 he directed all line assessors to give considerable weight to the 1985 assessments arrived at for 1985 but to alter them if market data and other considerations warranted a change. He explained that economic conditions in the early 1980s, which included overbuilding and high interest rates, had resulted in an oversupply of office space, making it unlikely that building values would increase between January 1, 1984 (the valuation date for tax year 1985) and January 1, 1985 (the valuation date for tax year 1986). For the 1985 assessments the Board had reduced, Klugel directed assessors to determine the validity of the Board's valuations in light of available data. Where the 1985 Board valuations appeared justified, these were to be used as base figures for 1986 assessments, but where Board figures were unjustified, assessors were to use the Department's originally proposed 1985 figures. In all cases, 1985 valuations were to be modified if available information demonstrated a reason to change the valuation for 1986. Klugel stressed to his assessors that each property "starts off a tax year fresh." Assessors, therefore, were not to see themselves bound by the Board's prior year valuations.

Appellant Wolf, whose law firm in the building had received a below-market rental rate, testified that the proper 1986 assessed value for the building was the property's tax year 1984 valuation. He argued that the value of the building had not increased between January 1, 1983 and January 1, 1985 because the actual net income from the building had not increased during that period. He explained that the building was in a "time warp" because of "the structure, its age, its amenities, its lack of amenities, and first and foremost, its [below market rate] leases." In addition, he concluded that the net operating income from the property went from $1,136,440 in 1982 to $1,218,512 in 1983 and back down to $1,167,944 in 1984. He did not, however, estimate future "income earning potential," nor did he use the comparable sales method of valuation.

The trial court sustained the Department's assessment for tax year 1986, concluding that the assessment figure represented "a reasonable and conservative estimate of value in view of other sales and upon review of the indicated value obtained by the income capitalization approach." The court was satisfied that the Department had conducted a new assessment for 1986 because the assessor had made an independent analysis that took into consideration new information not available in the prior year. The court concluded that, overall "the assessors applied the generally recognized approaches to value in making the assessment for tax year 1986. The resulting assessment appears to be justified from the evidence. Therefore, the decision of the Board of Equalization and Review should be affirmed" (citation omitted).

The trial court also found appellants' proposed valuation "flawed factually and legally" primarily because their income approach to value was based on "a snapshot of a single year's income and expenses" and because they had made no effort to take into account longer term income potential or comparable sales.

II.

Appellants argue that the trial court erred in concluding that the District conducted a genuine reappraisal of their property for tax year 1986 because, they maintain, the District simply reiterated its own tax year 1985 assessment despite the Board's reduction of that 1985 assessment. They rely on District of Columbia v. Burlington Apartment House Co., 375 A.2d 1052 (D.C. 1977) (en banc), in which we held that "an equalized assessment from the Board . . . becomes the basis for taxation until a subsequent reassessment has been made according to law." Id. at 1056. In Burlington Apartment House, we refused to validate an assessment that "was exactly the same as that which had been set for the previous fiscal year by the Board," because "it is clear that the [new] figure was not based upon a reassessment utilizing updated sources of information, but rather was simply a routine repetition of the [previous year's] assessment." Id. at 1056 n. 8.

Assessments are not necessarily invalid because they are the same as in the previous year. See Brisker v. District of Columbia, 510 A.2d 1037, 1040 (D.C. 1986). Nor are they invalid because, in the course of reassessing, the assessor looked at the prior assessment. See id. In this case, the trial court specifically found as a matter of fact that the reassessment relied on updated sources of information:

The taxpayer attempted to show that no assessment was made for the property for tax year 1986 because the same assessment for 1985, which had been rejected by the Board of Equalization and Review, was repeated. Although the assessment for both years was the same, the evidence shows that the property was assessed again in tax year 1986. The fact that the new assessor relied in part upon information developed by the prior assessor does not alter the validity of the assessment. He made an independent analysis, conferred with his superior, and concurred in the results. Further, additional information was taken into consideration when the assessment was made for tax year 1986.

Wagner, J., Findings of Fact, Conclusions of Law and Order Affirming Assessment at 11 (Aug. 18, 1989) (Order).

Our review of Tax Division appeals is the same as it is for other civil cases tried without a jury. See D.C. Code § 47-3304(a) (1990). "The trial court's factual findings are binding upon this court 'unless they are clearly erroneous; if the findings are acceptable, we will not disturb the court's judgment unless it is plainly wrong or without evidence to support it.' " George Washington Univ. v. District of Columbia, 563 A.2d 759, 761 (D.C. 1989) (quoting Rock Creek Plaza-Woodner Ltd. Partnership v. District of Columbia, 466 A.2d 857, 859 (D.C. 1983)); see D.C. Code § 17-305(a) (1989).

Appellants argue that the testimony at trial clearly shows that the 1986 assessment was merely a routine reiteration of the original 1985 assessment and that assessor Davis felt compelled merely to repeat the 1985 assessment made by Klugel, his superior. The trial court, however, found otherwise:

5. . . . After going over the data with Mr. Klugel, [Mr. Davis] agreed with the figure indicated by the Chief of Standards and Review. Mr. Davis had also examined the income for the subject property for at least two years and market data for other income producing properties in the city. Mr. Davis and Mr. Klugel also reviewed equalization charts. . . .

* * * * * *

7. . . . In this case the line assessor concurred with the conclusions reached by Mr. Klugel after reviewing all the available data. . . .

8. . . . For tax year 1986, [Mr. Klugel] also had the owners' income and expense statement for 1983, as well as the information about income streams for other office buildings in the city. He also had leasing information for the subject property. Based upon the information, he felt the change from the Board's results in the prior year was justified as did Mr. Davis.

Order at 4-6. We cannot say that the court's decision to credit the testimony of the assessors was "plainly wrong or without evidence to support it." D.C. Code § 17-305(a). "Where there are two permissible views of the evidence, the factfinder's choice between them cannot be clearly erroneous." Anderson v. Bessemer City, 470 U.S. 564, 574, 105 S.Ct. 1504, 1511, 84 L.Ed.2d 518 (1985). Mr. Davis testified that he made use of some figures from 1985 but that he had independently evaluated them with attention to "arriving at the best equalization among office buildings;" he also conducted an independent comparable sales analysis. In addition, assessor Davis flatly denied appellant Wolf's charge that Klugel had told him to repeat the prior year's assessment. Klugel testified, moreover, that he had evaluated new data on income streams that had not been available to him in 1985. Under these circumstances, we cannot say the trial court's judgment was unsupported by the evidence.

III.

We turn to appellant's challenge to the District's valuation methods. "The assessed value of property for real property taxation purposes shall be the 'estimated market value' of the property on January 1st of the year preceding the tax year." District of Columbia v. Washington Sheraton Corp., 499 A.2d 109, 112 (D.C. 1985) (citing D.C. Code § 47-820(a) (1981)). The D.C. Code defines "estimated market value" as:

100 per centum of the most probable price at which a particular piece of real property, if exposed for sale in the open market with a reasonable time for the seller to find a purchaser, would be expected to transfer under prevailing market conditions between parties who have knowledge of the uses to which the property may be put, both seeking to maximize their gains and neither being in a position to take advantage of the exigencies of the other.

D.C. Code § 47-802(4) (1990). In determining the "estimated market value," the assessor must "take into account any factor which might have a bearing on the market value of the real property. . . ." Id. § 47-820(a). The regulations promulgated under the statute "give the Director of Finance and Revenue discretion in choosing the method or approach for an assessor to use in estimating the market value of a particular property." Safeway Stores, Inc. v. District of Columbia, 525 A.2d 207, 209 (D.C. 1987); see 9 DCMR § 307.2 (1986) (Director may apply "one or more of the generally recognized approaches to valuation set forth in this section or any other method the Director deems necessary to arrive at estimated market values"). Appellants argue the District incorrectly applied two of the "generally recognized" approaches to valuation: the "income" and "comparable sales" methods.

A.

The "income" approach to valuation "bases assessed value on the amount that investors would be willing to pay to receive the income that the property could be expected to yield. . . ." 9 DCMR § 307.5 (1986). That approach

entails deriving a "stabilized annual net income" by reference to the income and expenses of the property over a period of several years. That annual net income is then divided by a capitalization rate — a number representing the percentage rate that taxpayers must recover annually to pay the mortgage, to obtain a fair return on taxpayers' equity in the property, and to pay real estate taxes.

Rock Creek Plaza-Woodner, 466 A.2d at 858. In conducting the analysis in this case, the assessors determined the estimated market value of the property by using a "stabilized net income" figure and applying a capitalization rate to arrive at a total value. The stabilized net income figure of $1,797,588 was obtained by multiplying the square footage of the finished area in the building by $11.50. The assessors then capitalized this income figure to arrive at an estimated market value of $14,520,500.

Appellants argue that the District's "income" approach was flawed because the assessors disregarded the actual income and expenses of the building in favor of creating an estimated "stabilized net income." We rejected a similar argument in Washington Sheraton, however, where we held that

[e]stimated market value is not determined, as [appellant] suggested, by reference to "income available to the property as of the assessment" but by reference to "income earning potential." The fundamental notion that the market value of income-producing property reflects the "present worth of a future income stream" is at the heart of the income capitalization approach.

499 A.2d at 115 (citations omitted); see 9 DCMR § 307.5 (1986). Actual earnings, of course, may be relevant evidence of a building's future "income earning potential," but it is the future potential, not the current earnings themselves, that must constitute the legal basis for valuation. In assessing 1001 Connecticut Avenue, therefore, the District was not required to confine itself to current earnings but could take into account other information relevant to estimating the future income stream an investor could expect from the building. And the trial court found that the District had done just that:

[The assessors] obtained the [stabilized net income] figure by examining the income and expense statements for the subject property for 1983, and earlier years and the income streams for numerous other office buildings in the city. . . . Mr. Davis had also examined the income for the subject property for at least two years and market data for other income producing properties in the city. Mr. Davis and Mr. Klugel also reviewed equalization charts.

Order at 4-5.

One reason, under the income method, for the focus on future income potential is that the actual income from the building may not reflect what a reasonable buyer "would be willing to pay to receive the income that the property would be expected to yield." 9 DCMR § 307.5 (1986). For instance, if the income from the building is depressed because the owner entered into below-market leases that were not arm's length transactions, the income stream of the building owner would not necessarily reflect the total income-earning potential a willing buyer could expect from the building. See Folsom v. County of Spokane, 106 Wn.2d 760, 769, 725 P.2d 987, 992b (1986) (en banc). In the most egregious cases, landlords and tenants could manipulate rent levels and other economic variables to minimize tax payments. See, e.g., Safeway Stores, 525 A.2d at 211-12 (discussing use of sale and leaseback arrangements to minimize taxes if District were required to base assessment on actual rent levels.) Similarly, if a below-market lease would expire by its terms within a short time so that a willing buyer could be expected to ignore its short-term burden on the property's income-earning potential, such a lease should not necessarily constrain an assessor's exercise of judgment in determining market value. See Folsom, 106 Wn.2d at 769, 725 P.2d at 992. On the other hand, a purchaser would probably be unwilling to pay full market value for property encumbered by long-term below-market leases which the purchaser would be required to assume, unless the lease permitted the lessor to pass the tax burden on to the lessees. See id. 106 Wn.2d at 767, 725 P.2d at 991. The fact is:

The amount of rental fixed by a lease, even though negotiated at arm's length, could be very misleading, as to true value of property, for it is well known that many rental contracts may be at excessive or inadequate rentals because of poor business judgment on the part of one party or another[, or because long-term contracts were] made in boom times or in times of depression. . . .

People ex rel. Gale v. Tax Comm'n, 17 A.D.2d 225, 230, 233 N.Y.S.2d 501, 506 (1962). See also 72 AM.JUR.2D State and Local Taxation § 760 (1974); Annotation, Income or Rental Value as a Factor in Evaluation of Real Property for Purposes of Taxation, 96 A.L.R.2d 666, 678-79 (1964).

We need not decide how leases under various circumstances should be considered in determining market value. We can say on this record, however, that the trial court did not err in refusing to determine value solely by reference to income from the building's leases. Proper application of the definition of "estimated market value" found in § 47-802(4) requires consideration not merely of actual earnings but of an adjusted income figure reflecting a variety of factors (including the impact of current leases) that influence the market value of the potential income stream of the building.

The trial court was aware that below-market leases encumbered the property. The court, however, correctly discounted the importance of these leases for an accurate income valuation on this record. The court noted that

[Mr. Wolf] conceded that an investor would look at 5 years of income and expenses to make projections [of future income]. [Moreover, he] failed to make an adjustment for the substantial income loss for the property due to the substantial rent concession given his law firm. The failure to project the potential income for the property is inconsistent with the income approach to value. The failure to make adjustments for rents substantially below market which [adjustments] could be achieved [through anticipated expiration of the leases] within a reasonable period ignores the income potential for the property. Therefore, this analysis should be rejected.

Order at 7.

Under these circumstances, we sustain the trial court's view that the District's use of past earnings and other market data to determine future income potential was consistent with our precedents and with statutory requirements.

B.

An assessor may also employ the comparable sales approach to real property valuation. This approach "bases assessed value on the price or prices at which reasonably comparable properties have recently sold." 9 DCMR § 307.3 (1986) (emphasis added). Similarly, D.C. Code § 47-820(a) provides that the District shall take into account "sales information on similar types of real property." (emphasis added); see 9 DCMR § 307.1(b) (1986).

Appellants contend the trial court erroneously accepted the District's comparable sales data because the District gave no testimony regarding the leases, the physical condition, or the acquisition financing terms which would have a significant bearing on the total sales prices of the comparable property. Without such testimony, appellants contend, comparability cannot be shown because gross prices are meaningless.

The statute and regulations that define the comparable sales approach refer to comparisons of "similar types" of property and "reasonably comparable" property, recognizing that different properties will rarely be identical and thus that comparable sales data need not reflect perfect comparability. In this case, the court found that the assessors compared recent land sales in which

prices for the properties ranged from $422.63 to $1,194.40 per square foot of land area. [Appellants'] property was valued at $690 per square foot of land area. . . . The assessor's estimate of value took into account differences in the location, size, configuration and other characteristics which make one property more valuable than another.

Order at 3. The court then found that the assessors compared recent building sales using the comparable sales approach:

[The assessor] analyzed building sales west of 15th Street. Among these were 1250 Connecticut Avenue, 1000 16th Street, N.W. and 1625 K Street, N.W. Like the subject property, each of these properties are older buildings. The Connecticut Avenue property sold for $156.82 per square foot of finished area; the Sixteenth Street property, for $75.45 per square foot of finished area; and the K Street property, for $107.48 per square foot of finished area. The value of the subject property was estimated by the assessor at $93.53 per square foot of finished area. This figure represents a reasonable and conservative estimate of value in view of other sales and upon review of the indicated value obtained by the income capitalization approach.

Id. at 4. When the District has selected buildings that are "reasonably comparable" to the building subject to assessment (based on such usual criteria as location, age, and configuration), the District is entitled to presume that the sales prices for the buildings reasonably reflect market prices properly used for comparable sales analysis. See, e.g., Shawmut Inn v. Town of Kennebunkport, 428 A.2d 384, 395 (Me. 1981) (recent public sale of real property is evidence of market value). The District need not undertake laborious comparisons of acquisition financing arrangements to conclude that buildings sold within approximately the same time frame were subject to similar market forces.

"[A] taxpayer bears the burden of proving that an assessment is incorrect or illegal. . . ." Safeway Stores, 525 A.2d at 211; see Super.Ct.Tax R. 11(d). Appellants accordingly were entitled to introduce evidence regarding the financing, lease terms, and other characteristics of the buildings used in the District's comparable sales analysis, and to attempt to prove that there was something unusual about these arrangements that affected the reported sales prices in a way that caused them not to reflect normal sales prices for buildings comparable to the one under assessment. Appellants, however, introduced no evidence of any kind to challenge the District's choice of comparable properties. Appellants, therefore, have failed to rebut the District's comparable sales analysis.

IV.

Finally, appellants contend the trial court erred in failing to release them from the burden of proving that the District's original 1986 assessment of $14,620,500 was incorrect. They argue that by attempting to prove the proper assessment for 1986 should have been $17,830,000, the District "abandoned" its original $14,620,500 assessment and thus assumed the burden of proving that the entire revised $17,830,000 assessment was correct. According to appellants, if the District failed in carrying that burden, then the entire 1986 assessment failed, leaving in place the last assessment conducted in accordance with law: the $13,539,022 assessment levied by the Board of Equalization and Review for tax year 1985. See Burlington Apartment House, 375 A.2d at 1056.

Appellants argue, more specifically, that under Super.Ct.Tax Rule 11(d), see supra note 7, the District was required to assume the burden of proof "[i]n respect to any new matter pleaded in its answer" (emphasis added), which in this case meant the burden of proof regarding to the entire new assessment. We disagree. The original assessment of $14,620,500 obviously implied that the property was worth at least that amount. The newly proposed assessment is consistent with that proposition. The fact that the District now contends the property is worth even more cannot, for that reason, shift from the taxpayer to the District the burden of proof as to the lower figure, which the District has always stood behind. If anything, the District's proposed increased assessment has placed even greater emphasis on the District's position that $14,620,500 is not too high. Accordingly, the burden remains on the taxpayer to establish the contrary.

Appellants also rely on District of Columbia v. ACF Indus., Inc., 122 U.S.App.D.C. 12, 350 F.2d 795 (1965), for the argument that once the District explicitly disclaims reliance on its original legal position, it assumes the burden of proving the correctness of its entire new case. See id. at 15 n. 11, 350 F.2d at 798 n. 11. Appellants' argument, however, is inconsistent with the facts of this case. The District's witness, Klugel, testified that the District was "not backing off where we were originally" and that the original assessment figure was correct based on the information available at the time. Rather, the District increased its assessment based on data submitted by appellants in support of their petition for refund to the Superior Court. The trial court specifically credited the assessor's testimony in its findings of fact: "[Mr. Klugel] states, however, he was not 'backing off' from where the assessment was in tax year 1986." Order at 9. Unlike the situation in ACF Industries, the District neither "abandoned" its original data nor changed its legal theory.

Under Super.Ct.Tax R. 11(d), then, the burden of proof shifted to the District only with respect to the new data it introduced to support an increase over the original $14,620,500 assessment for 1986 — an assessment which the Board already had approved. The burden therefore remained with appellants to prove the incorrectness of the original 1986 assessment. See Brisker, 510 A.2d at 1039. Because appellants failed to carry that burden, see supra Part III, the trial court correctly upheld the Board's decision affirming the District's 1986 proposed assessment.

Affirmed.