Opinion for the Court filed by Circuit Judge SPOTTSWOOD W. ROBINSON, III.
Dissenting and Concurring Opinion filed by Senior Circuit Judge MacKINNON.
SPOTTSWOOD W. ROBINSON, III, Circuit Judge:
Today we conclude yet another chapter in the protracted dispute between D.C. Transit, Inc. (Transit), formerly the franchiser of mass transportation services in the Washington metropolitan area,1 and its patrons. The specifics of the controversy have been detailed in our prior decisions,2 and need only be briefly recounted from time to time. In Democratic Central Committee v. Washington Metropolitan Area Transit Commission (DCC I)3 and Democratic Central Committee v. Washington Metropolitan Area Transit Commission (DCC II)4 we reviewed Orders Nos. 7735 and 10526 of the Washington Metropolitan Area Transit Commission, which authorized, respectively, fare raises for Transit in 1968 and 1970. In those cases, we invalidated the increases and held that Transit’s riders were entitled to restitution for the overcharges.7 We remanded to the Commission for computation of the amount of restitution, and retained jurisdiction in full.
Our task now is to evaluate the Commission’s calculation of the restitution award [405]*405and to resolve related issues raised by the parties. In Part I of this opinion, we consider the Commission’s holding that Transit was sufficiently viable and efficient in 1970 to reap the benefit of a fare increase, and conclude that substantial evidence supports the Commission’s findings in this regard. In Part II, we examine the Commission’s identification of properties converted by Transit from operating to nonoperating status, the Commission’s computation of the amount of value appreciation on those properties, and the extent to which that amount should be shared by Transit’s fare-payers. In Part III, we allow the Commission reimbursement from the restitutionary fund for the expenses it incurred in connection with the remand, but hold that all other parties should bear their own costs. We decline to rule on the request for attorneys’ fees at this time, and instead remand to the Commission for additional findings pertinent thereto.8
I. Efficiency and Viability
The Washington Metropolitan Area Transit Regulation Compact, under which Transit operated, stipulated that the Commission could not call upon farepayers to bear the cost of inefficient management,9 and thus required the Commission to consider Transit’s operating efficiency before authorizing any fare increase. We ourselves held that Transit’s patrons could not be compelled to furnish a reasonable rate of return to investors if its operations were inherently unprofitable, and that therefore the Commission must satisfy itself that Transit was economically viable before allowing a higher fare.10
In DCC II, we concluded that the Commission did not discharge its duty to consider efficiency and viability when in 1970 it set a new fare in Order No. 1052.11 We noted that the gravity of this omission was underscored by the Commission’s denial of a 1972 fare increase because Transit did not meet the efficiency and viability criteria.12 We directed the Commission to examine these factors on remand and tell us whether there was a lack of efficiency or viability in 1970.
In compliance, the Commission sponsored a study by Pasquale A. Loconto exploring Transit’s efficiency and viability at the time of the 1970 fare increase.13 Loconto had previously reported on Transit’s 1972 operating condition, and that report had played a dispositive role in the Commission’s decision to deny Transit’s request for a fare increase that year.14 In addition, a Commission hearing examiner conducted 96 days of testimony on Transit’s 1970 financial status, which culminated in the issuance of a 448-page report on efficiency [406]*406and viability issues.15 The Commission, relying on the 1970 Loconto report and other evidence, upheld the hearing officer’s finding that Transit was both efficient and viable in 1970.16 Petitioner Black United Front (BUF) disputes this determination on several grounds.
BUF first contends that the Commission’s holding that Transit was managed efficiently in 1970 is not supported by the record evidence. In this regard, BUF asserts that a comparison of the two Loconto reports reveals that the same features that led to the Commission’s finding of managerial inefficiency in 1972 also appeared in the 1970 Loconto Report.17 Our review of those two reports, as well as the reports of the hearing officer and the Commission, leaves us in disagreement with BUF’s contention. There is ample evidence in the record to underpin the Commission's conclusion that Transit’s 1970 financial woes were caused, not by managerial inefficiencies, but by social factors beyond its control.18 Accordingly, we affirm the Commission’s ruling that Transit was efficiently managed at the time of the 1970 fare elevation.
BUF also argues that the Commission misconstrued the test of viability we articulated in DCCII.19 Therein we stated that, in order to determine whether Transit was viable in 1970, the Commission should investigate and determine
(a) if and to what extent the company would have been able to make a profit if there were no regulation at all, and (b) if and to what extent Transit could then earn a sufficient return so as to make it an attractive investment at any level of fares which could have been deemed “reasonable.”20
In phrasing our test that way, we asked the Commission to assume that Transit was operating in a hypothetical unregulated environment, and to disregard the knowledge gained from hindsight of Transit’s condition after 1970. The Commission found, on the basis of conservative financial estimates, that in 1970 Transit had the potential to continue to generate modest profits and thus it retained the interest of its shareholders and creditors.21 We find that the Commission’s determination of viability is based on substantial evidence, and that the Commission properly carried out our instructions.22
[407]*407The Commission thus has cured its neglect of Transit’s efficiency and viability when it promulgated Order No. 1052 by investigating and determining those matters on remand. It follows that Transit’s farepayers are not entitled to any restitution on the now-refuted theory of a lack of efficiency or viability on Transit’s part in 1970.
II. Property Issues
In DCC I and DCC II, we found that Orders Nos. 773 and 1052 were defective because the Commission had not considered the extent to which appreciation in the value of Transit’s properties might have obviated the need to generate additional revenue through fare increases.23 We held that Transit’s farepayers were entitled, as restitution for fares unjustly exacted, to the accrued appreciation in value of in-service properties subsequently converted to non-operating status.24 We instructed the Commission to determine the amount of restitution due the farepayers by first sub-stracting the book value of each identified property from its market value at the time it was transferred out of service25 and then deducting the expenses that would have been incidental to any contemporaneous sale of the property.26
On remand, the Commission identified sixteen properties27 and estimated the market value of each on the date of its transfer to nonoperating status. From the property’s then market value, the Commission subtracted its net book value at the time it was acquired by Transit, and the brokerage fees and tax expenses that Transit likely would have incurred had the property been sold.28 The Commission concluded that Transit’s farepayers are entitled to the benefit of $3,947,134 in appreciation to offset [408]*408the increase in fares.29 Transit and petitioners BUF and Democratic Central Committee of the District of Columbia (DCC) dispute the Commission’s action in numerous respects, and we now address their contentions in turn.
A. Identification Issues
The first claim is that the Commission erred in identifying the properties to be included in the computation of the restitution award. BUF and DCC argue that the Brookland Garage and the Eastern Garage30 were not used for operating purposes after September, 1966, and that therefore the farepayers should receive the benefit of value appreciation on those properties.31 The Commission supports its exclusion of the two properties by adverting to its 1966 Order No. 634,32 which directed Transit to retain the Brookland and Eastern Garages as operating properties in order to meet supplementary service requirements should they arise.33 We agree that Order No. 634 is dispositive on the question of operating status of these properties and validates the Commission's decision to omit them from the calculation of accrued appreciation. The properties cannot be deemed to have been transferred out of operating status simply because the contingency for which they were held in service never occurred. We affirm the Commission’s refusal to include the Brookland and Eastern Garages in the restitution calculus.
Transit argues that the Commission erred by counting the Fourth Street Shop, the Southern Carhouse and the Georgia & Eastern Terminal among the identified properties because, Transit says, the gains on those properties were allocated by earlier orders of the Commission and its predecessor, the Public Utilities Commission of the District of Columbia (PUC).34 Those orders, Transit asserts, have preclusive effect, and bar any allotment of gains on the three properties to farepayers.
Transit’s contention impels us to examine closely the earlier orders and the contexts in which they arose. The Fourth Street Shop and the Southern Carhouse were transferred out of service in 1959 when they were purchased by the District of Columbia Redevelopment Land Agency at a price greatly in excess of their original cost to Transit.35 PUC considered the gain realized upon their sale in Order No. 4577.36 In the proceeding leading to that order, Transit requested an exception from standard public-utility accounting practices, which required all amounts received from the sale of depreciable property to be credited to the farepayers’ depreciation reserve as salvage.37 Transit argued that the properties’ high selling price served to rebut the assumption underlying the standard practice, namely, that the value of depreciable property will decrease with time.38 PUC credited $613,661.28 from the sale proceeds to the riders’ depreciation reserve fund in order to compensate the farepayers for excessive depreciation accruals they had funded through payment of fares.39 The remaining $837,210.75 of the gain realized from the sale of the depreciable portions of [409]*409the properties, along with all of the gain on the land, was credited to Transit’s earned surplus account, and thus inured to the benefit of Transit’s investors.40 We affirmed PUC’s disposition in 1961.41
The Georgia & Eastern Terminal was transferred out of service in 1960, and sold privately approximately two years later.42 When the Commission was called upon to distribute the proceeds from the sale of the terminal in Order No. 563,43 it credited all of the profit to Transit’s earned surplus account.44 The Commission’s decision was not appealed.
In order to determine the effect of PUC’s Order No. 4577 and the Commission’s Order No. 563 on the problem before us, we are guided by venerable principles of issue preclusion. Generally, “[w]hen an issue of fact or law is actually litigated and determined by a valid and final judgment ... the determination is conclusive in a subsequent action between the parties, whether on the same or a different claim.”45 With but few exceptions, however, issue preclusion cannot be asserted against a nonparty to a prior proceeding,46 and preclusive effect is given only to issues “actually litigated and ... essential to the judgment” therein.47 The party invoking the prior judgment as a barrier to relitigation has the burden of establishing that the conditions for preclusion have been satisfied,48 and Transit has not met that burden here.
The allocation of the gain on the Fourth Street Shop and the Southern Carhouse in PUC’s Order No. 4577 does not foreclose a reallocation in this case because the parties here are not identical to, or in privity with, the parties to the earlier litigation. Only Transit and the Commission — then PUC— were parties to the proceeding leading to Order No. 4577 and judicial review thereof;49 the farepayers had no presence or representation therein at all. While a non-party may under certain conditions be bound when “[a]n official or agency invested by law with authority to represent the person’s interests” was a party to the first proceeding,50 that proposition can have no bearing here. PUC’s representation of the public interest was not exclusively for fare-payers and the many battles fought by [410]*410citizens against fare increases for Transit51 illustrate that the Commission’s representation of them was clearly less than the advocacy of private parties.52 Furthermore, it would be unfair to now forestall farepayers simply on the basis of PUC’s participation in the earlier proceeding because the interests of PUC and Transit’s farepayers differed markedly.53 The position advanced by DCC and BUF in the DCC cases — that all in-service property appreciation should be allocated to farepay-ers — was not advocated by PUC when it issued Order No. 4577, and was in fact opposed by the Commission, its successor, both in DCC I and DCC II. Our DCC holdings cannot be frustrated by a prior proceeding in which the farepayers had no meaningful voice.
The allocation of the gain from the sale of the Georgia & Eastern Terminal in Order No. 563 similarly fails to bind the parties here. While the interests of farepay-ers were represented in the proceeding culminating in that order, the question of proper allocation of in-service appreciation was neither actually litigated nor necessary to the outcome thereof. Order No. 563 was precipitated by this court’s determination in D. C. Transit System, Inc. v. Washington Metropolitan Area Transit Commission 54 that any gain realized on depre-ciable property sold in consequence of Transit’s termination of trolley service must be used to offset the farepayers’ liability for losses suffered on other property conveyances occasioned by the conversion from a trolley-bus to an all-bus system.55 We remanded to the Commission to enable it to determine whether the profitable sale of the Georgia & Eastern Terminal was a result of the conversion and, if so, to “address itself to the question ... whether the riders should be afforded some participation in the benefits of the sale.”56 There is no indication that the parties litigated any other issue on remand. The Commission found that “the sale of the terminal was occasioned neither in whole nor in part by the abandonment of rail operations,”57 but went further, however, to say that “the ratepayer is not entitled to a share in any portion of the proceeds of that sale, unless there was a profit on the depreciable portion of the asset sold. There was none in this case.”58
We decline to give the latter statement any preclusive effect with regard to the existence or ultimately proper allocation of in-service value appreciation of the Georgia & Eastern Terminal. The question of allocation was not raised or litigated by the parties,59 and a determination of that mat[411]*411ter was not essential to the Commission’s decision, for once it found that the Georgia & Eastern sale was not prompted by the conversion, the purpose of this court’s remand was achieved.60 Under these circumstances, we refuse to accept the Commission’s inconsequential observation in Order No. 563 as a barrier to the farepayers’ endeavor here.
The absence of preclusion does not, however, lead us to allocate the entire gain on these three properties to the farepayers. When PUC issued Order No. 4577, it directed that $613,661.28 of the gain realized on the sale of the Fourth Street Shop and the Southern Carhouse be credited to Transit’s depreciation reserve,61 and that credit redound to the benefit of the farepayers. Consequently, our calculation of the fare-payers’ entitlement must be reduced by an equivalent amount to avoid a double benefit.
B. Calculation of Gains
Petitioners raise four issues concerning the Commission’s computation of gains by appreciation of the identified properties. We consider each of these disputes seri-atim, and find that the Commission ruled correctly in most respects but erred in several.
1. Accounting Methods
Transit contends that in calculating the gain allocable to farepayers, the Commission should have employed the “market-to-market” method of accounting62 rather than the “book-to-market” method.63 Because the market value of the properties exceeded their book value — their cost to Transit — at the time they were acquired, Transit asserts that the book-to-market method denies it the benefit of bargain purchases.64 We have weighed and rejected this very argument in both of our prior DCC decisions. In DCC I, we told the Commission to compute the “dollar amount of restitution ... by subtracting the book value of the properties from the market value at the time of the transfer.”65 Similarly, in DCC II, we directed the Commission to calculate “the amount of the increase in market value over book value of lands which Transit” transferred out of service.66 On remand, the Commission heeded our instructions, and we can see no reason to reconsider them now.
2. Value of the Fourth Street Shop and the Southern Carhouse
As we have mentioned, the Fourth Street Shop and the Southern Carhouse were sold under threat of condemnation to the District of Columbia Redevelopment Land Agency for a combined price of $2,954,693.67 On remand, the Commission decided that for purposes of restitution it would calculate appreciation on these properties by utilizing their market value, rather than their actual selling price, at the time. The Commission found that the selling price did not accurately reflect true market value since the sale took place in the presence of a looming prospect of con[412]*412demnation.68 On this account, the Commission based its computation of gain upon its expert’s estimate of their combined market value of $1,847,50069 when the sale occurred. BUF objects to the use of estimated market values for properties sold simultaneously with their transfer out of service,70 and argues in the alternative that the Commission should simply have accepted the actual sale price of the two properties as conclusive evidence of their market value.71 We hold that, for the purpose of calculating the gain allocable, the sale price should have been employed.
The Commission misconceived the role of market value in determining the amount due farepayers as restitution. Generally speaking, estimated market value is pertinent, only because — and only to the extent thatr — we lack a selling price for the date pertinent.72 With respect to the two properties under discussion, however, the selling price is available, and its use is more appropriate because it provides precisely the information that only less dependably could be sought by an appraisal of market value. Had the appraiser’s estimate of market value exceeded the actual sale price, it would have been unfair to require Transit to make restitution in an amount greater than the profit actually realized; by the same token, Transit is not entitled to a windfall merely because the sale price of the Fourth Street Shop and the Southern Carhouse exceeded market value by more than $1 million.73 The theory underlying our DCC decisions74 dictates the conclusion that farepayers should receive the benefit of the actual gain on the properties in this instance.75
3. Brokerage Fees and Taxes on the Sale of the Fourth Street Shop and the Southern Carhouse
BUF lofts a similar objection to the Commission’s allowance of deductions for theoretical brokerage fees and federal taxes in connection with the sale of the Fourth Street Shop and the Southern Carhouse.76 Since Transit paid no brokerage fees or [413]*413taxes when it sold these properties, BUF argues that the Commission should not have permitted deductions for these theoretical expenses.77 We agree with BUF that only brokerage fees actually paid should be subtracted from amount of appreciation due farepayers. Because, however, taxes on the sale were merely deferred, not forgiven, we hold that tax expenses on the two properties should be computed in the manner we later prescribe for the other identified properties.78
Our decision that a deduction for brokerage fees should be limited to those actually paid follows from our ruling that the actual net sale price for the properties guides the amount of restitution to which farepayers are entitled. In DCC I, we directed the Commission to calculate the net gain on the identified properties by subtracting from the amount of value appreciation “the taxes and sale expenses which would have been deducted from Transit’s profit if the assets had been sold outright instead of simply being moved into nonoperating status.”79 Here again we need not use an estimate, for the properties were “sold outright” on the same day they were moved “below the line” — that is, from operating to non-operating status. Since the sale under scrutiny was effected without payment of any brokerage fee, the Commission’s allowance of a deduction for such a fee conferred a windfall on Transit.80
Tax expenses are distinguishable from other sales costs in one important respect. Federal tax liability on the sale of the Fourth Street Shop and the Southern Carhouse was deferred because Transit invested the proceeds from the sale in “like-kind property.”81 Unlike brokerage fees, which will never be paid, taxes attributable to the gain on these properties will ultimately fall on Transit when it disposes of the replacement properties.82 Consequently, the tax liability on these properties should be deducted from the amount payable to farepayers as restitution.
4. Capital Gains Tax Calculations
In the DCC cases, we remanded to the Commission with instructions to calculate the capital gains taxes on all appreciated properties, and to deduct the amount thereof from the farepayers’ restitution award.83 The Commission computed the tax expense prospectively, reckoning that future dispositions could result in a 28.75 percent tax rate on property appreciation, and concluding that Transit was entitled to a deduction for taxes at that rate.84 The farepayers [414]*414attack this calculation from several quarters.
BUF and DCC first challenge Transit’s entitlement to any deduction at all for capital gains taxes. They note that fare-payers have already been required to shoulder Transit’s tax burden in the form of increased fares, since each rate escalation included a component to compensate for additional income taxes generated thereby.85 They further contend that Transit stands to benefit from a substantial tax deduction when it makes restitution.86 These parties therefore insist that fairness militates against any requirement that farepayers take on Transit’s capital gains taxes.
We believe that these arguments overlook a key factor. It is true that the Commission, during Transit’s operating years, set fares at a level sufficient to produce enough revenue to cover Transit’s income tax expenses. BUF and DCC, however, fail to acknowledge that restitution will reimburse farepayers for the totality of fare excessiveness. Farepayers thus will be made whole once the process of restitution is completed.
We also remain unpersuaded by the fare-payers’ assertion that no liability on their part for taxes need be recognized because Transit stands to recoup tax expenses through deduction of the restitution award. We put aside an identical contention in Bebchick III,87 stating that “[a]s for the taxes to be saved by Transit in the future years in which it pays restitution ..., we cannot calculate that saving or even [determine whether] it will exist.”88 Furthermore, petitioners’ argument is foreclosed by our determination in DCC I that Transit is entitled to offset its capital gains liability from the amount owing to farepayers.89 We find nothing new in the farepayers’ current objection, and hold that estimated capital gains taxes should be deducted from the restitution award.
The second objection, pressed only by BUF, relates to the Commission’s computation of the deduction for capital gains taxes. BUF insists that the Commission erred in predicating its calculation on anticipated future transfers of the properties,90 since we directed formulation of the deduction on the basis of the taxes Transit would have paid had it sold the properties on the dates they were taken out of service.91 The Commission endeavors to support its methodology by noting that “Transit cannot roll back the clock and sell the properties when the rates were lower or tax advantages would have been available,”92 and by arguing further that had property appreciation been taken into account when it authorized the fare increases, it would have computed the tax offset at the highest prospective marginal rate.93 We agree with BUF that the taxes should have been calculated as if the properties were actually sold on the dates they respectively shed their operating status, and we must remand to the Commission for recalculation of the tax offsets accordingly.
In our DCC cases, we ordered the Commission to compute and subtract from the restitution award “the taxes ... which would have been deducted from Transit's [415]*415profit if the assets had been sold outright instead of simply being moved into non-operating status.”94 This harmonized with our admonition in Bebchick 7/95 that any recovery by farepayers must “tak[e] into account taxes and costs which might have reduced the gain if the properties had been sold.”96 In light of this clear mandate, the Commission erred in calculating Transit’s tax offset by considering the assumed impact of hypothetical sales at wholly uncertain points in the future. The mere fact that the Commission would have deducted prospective taxes had it given attention to property appreciation in the formulation of the contested fare orders does not persuade us that it should do so now. Indeed, when confronted by the same argument in Bebchick III, we declared that “it is wholly reasonable to make a hypothetical recalculation of Transit’s taxes for the transfer years to see what tax impact the assumed gain would presumptively have had. There is no compelling need to try to compute the burden Transit will actually bear when it comes to sell the property.”97 Given the similarity of our directives in Bebchick II and the DCC cases, we think the rationale of Bebchick III controls here.
We therefore will remand to the Commission for recomputation of the tax offset on the basis of Transit’s tax posture in the years during which the identified properties were respectively transferred out of service. The offset should reflect Transit’s actual tax rate, and as well any credits or deductions that were available to Transit for the operative periods.98 The hearing officer entertained detailed testimony from a Commission staff member on Transit’s tax position during the years that properties were removed from service. The Commission would be well advised to draw upon this evidence in the calculation of Transit’s deductible tax expenses.99
C. Calculation of Restitution
In the previous sections of this opinion, we have delineated the methodology appropriate for computation of the amount of value appreciation available for inclusion in an award of restitution. Transit and BUF seek adjustments in the restitutional amount. Transit argues that the amount of restitution in DCC I should be limited to $738,720; that Transit should be permitted to set bus maintenance and cost-of-living expenses off against the amount of restitution; and that Transit is entitled to additional offsets by reason of equitable considerations. BUF asks for interest on the award of restitution. We now consider each of these claims.
1. Amount of Restitution Available in DCC I
Transit urges us to limit restitution in DCC I to $738,720, the aggregate of excess fares collected during the period in which the invalid fare raise allowed by Order No. 773 was in effect.100 Since this order superseded, and was in turn superseded by, rate orders that were never appealed by the farepayers, Transit argues that the Commission’s recommended award of $2,605,588 as restitution in that case violates principles of claim preclusion by reopening fare proceedings that were never challenged in court, and thereby deprives Transit of its property without due process [416]*416of law.101 We find these contentions unavailing.
Order No. 773 went into effect on January 28, 1968,102 and was replaced 277 days later by Order No. 882.103 Two further fare increases were authorized while Transit remained in operation under its franchise.104 The hearing officer and the Commission found that the fare set in Order No. 773 — the subject of review in DCC / — served as the base fare for all subsequent orders, and thus that its effect persisted until Transit ceased transportation operations.105 We agree with the Commission that the maximum amount of restitution allowable in DDC I is the fare increment authorized by Order No. 773 over the remainder of Transit’s life as a public utility.106 This conclusion does not disturb any authorization of an additional fare increase following Order No. 773, and thus raises no issue of preclusion or due process.107
2. Bus Maintenance and Cost-of-Living Allowances
Transit asks us to deduct from the amount of restitution the sums owed Transit for bus maintenance and cost-of-living allowances. In Bebchick II, we held that the Commission had undercompensated Transit for its expenditures for maintenance of its buses, and that Transit was entitled to recoup the balance.108 In a related case, we ruled that Transit was entitled to reimbursement for additional expenses of labor it incurred under a cost-of-living escalation clause in its bargaining agreement.109 Transit has requested that these sums be subtracted from the amount of restitution emanating from either Beb-chick III or this proceeding.110 Since the bus maintenance offset has already been allowed in Bebchick IV,111 we need only consider whether Transit is entitled to deduct the extra cost-of-living expenses from the restitution award herein.
In D.C. Transit System, Inc. v. Washington Metropolitan Area Transit Commission,112 we ordered that the added expense attributable to the cost-of-living clause “be set off against whatever amounts ... are determined to be necessary to restore to the farepayers through the equitable restitutional remedies man[417]*417dated” in other Transit cases.113 We think it appropriate to permit that offset here. The sum of $283,869,114 representing this item will accordingly be subtracted from the amount of restitution ultimately found due.
3. Equitable Considerations
Transit advances five grounds upon which it contends that equitable adjustments in the amount of restitution are in order. First, Transit maintains that the restitution should not be computed in a manner that would deprive its investors of a reasonable rate of return.115 The Commission estimated that the fares authorized by Order No. 773 would generate a net operating income of approximately $1.5 million, but Transit’s actual net operating income fell short of this calculation by approximately $1.3 million.116 Similarly, actual net operating income derived during the life of Order No. 1052 was nearly $5.5 million lower than Commission projections.117
Transit now argues, in effect, that it should be reimbursed for these income deficiencies. We cannot agree. A fare once set cannot be given retroactive operation by either the Commission or this court.118 The fares established by Orders Nos. 773 and 1052 were based upon the Commission’s best estimates of the amounts of revenue necessary to meet Transit’s costs of service and produce a reasonable rate of return for its investors. The simple fact that these estimates were not borne out by experience does not support Transit’s argument since, as we held long ago, Transit is not guaranteed a minimum rate of return.119 Transit’s investors were required to shoulder the risk that the company’s earnings might not support the expected return, just as they enjoyed the right to keep any larger amounts legitimately earned. Any other approach would have forced farepayers to insure Transit’s profitability.
Transit’s second equitable argument is that it should be permitted to retain the amount of value appreciation attributable to the difference between market value and book value of the identified properties on the date they were acquired.120 We have already considered and rejected this argument, and Transit gives us no reason to continue the dialogue.121
Third, Transit seeks reimbursement for monies paid to the District of Columbia in consequence of Transit’s contractual obligation to remove abandoned trolley tracks and repair the streets.122 At the time of the franchise agreement, PUC estimated the cost of doing so at $10,441,958 and established for that purpose a reserve to be subsidized by Transit at an annual rate of $1,044,196 for ten years.123 The annual accruals were treated as operating expenses and charged to farepayers through rate increases.124 By December of 1962, [418]*418accruals to the reserve totaled $6,656,-748.22, of which only $1,842,499.10 had been expended by Transit on track removal. At that time, the Commission estimated that track removal planned through mid-1965 would cost an additional $4.1 million,125 and ruled that, since the reserve was already sufficient to fund the projects anticipated, further additions to the reserve should be suspended indefinitely.126 We affirmed the Commission’s decision.127
In January of 1973, in contemplation of Transit’s imminent demise as a public utility, the District of Columbia assumed Transit’s track removal duties in exchange for a payment by Transit of $3,290,000.128 This amount exceeded the balance available in the reserve by $3,128,292,129 which Transit now claims as an offset against the restitution award. To buttress its position, Transit points out that when we approved the Commission’s decision to halt accruals to the reserve for track removal, we observed that “neither the Commission nor we have foreclosed Transit, should it in fact incur expenses for track removal in excess of existing reserves at some time in the future, from seeking to recover such- expenses from the users of its service.” 130 Since Transit had no opportunity to recover the excess of $3,128,292 from farepayers— because it was incurred after its franchise was terminated — it insists that equity calls for reimbursement through the medium of an offset in this amount.
Several factors convince us that Transit is not entitled to an equitable offset on this account. In the first place, we cannot know the extent to which the long delay in removing the trolley tracks caused the expense thereof to rise. From aught that appears, the accumulation in the reserve may have been adequate had the track removal program been carried out expediently; instead, the reserve was constantly and substantially eroded over the years by escalating costs. In the degree that Transit’s dalliance increased the expense of track removal, it would be unfair to charge farepayers by reducing the amount of restitution. In addition, we are left in the dark as to the effect of Transit’s settlement with the District. Obviously, fare-payers should not be saddled with what may have been a poor bargain on Transit’s part. And, regardless of whether Transit was made whole for its final track removal outlay by the condemnation award following the takeover of its transportation operation,131 Transit accepted the settlement with full knowledge of the fact that there would be no future ratemaking proceeding in which that expense could be recovered from farepayers. For these reasons, we hold that equity does not require a deduction from the amount of restitution to reimburse Transit for track removal.
In its fourth equitable argument, Transit seeks an offset for the $613,661.28 credited by the Commission to the farepayers’ fund at the time of the sale of the Fourth Street [419]*419Shop and the Southern Carhouse. 132 We have already considered this claim and upheld it.133
Finally, Transit argues that it should be permitted to recoup from the farepayers any deficiency that existed in its reserve for injuries and damages at the time its franchise was terminated.134 A Commission-sponsored study conducted in 1971 found that the reserve had a $1.6 million deficit.135 Transit contended that since it would have been entitled to recover this deficiency from its farepayers through increased fares, but as a result of the takeover lost the opportunity to do so, it should be allowed an equitable offset of the $1.6 million against the amount of the restitution award.
For much the same reasoning underlying our denial of a recovery for the track-removal expenses, we deny the request for an offset for the deficiency in the reserve for injuries and damages. Since Transit discontinued transportation operations before a new rate order charging the deficiency to farepayers could be considered,136 we do not know whether the Commission would have adopted the $1.6 million estimate of the deficiency, or whether the Commission would have ordered a fare increase on this account.137 Transit’s asserted right to this offset is thus entirely speculative, and we refuse to engage in the retroactive ratemaking that its recognition would necessitate.138 Moreover, the parties disagree, as they did with regard to track-removal expenses, on whether the condemnation award rescued Transit from the reserve deficiency. We reach the same conclusion here that we did before:139 Transit accepted the condemnation award in the face of a potential deficiency in the reserve, and with full understanding that in all likelihood further recourse against farepayers would be precluded. In these circumstances, we cannot say that the equities preponderate in Transit’s favor.
4. Interest
BUF and DCC urge us to allow interest on the amount of restitution due the fare-payers.140 Transit concedes that interest on the judgment fixing restitution is appropriate, but contends that prejudgment interest would be unjust and improper.141 Our task is first to determine the date from which interest should run, and then to consider the rate of interest proper.
BUF proposes alternatively three possible sets of “logical dates” from which interest might accrue: the dates upon which the appreciated properties were respectively removed from operation, the dates of improper fare increases, and the date of our decisions in DCC I and DCC [420]*420II. 142 Transit contends that interest cannot begin to run until we have determined the precise amount of restitution to be allowed.143 Since that amount was not fixed in our prior decisions144 — and is not computed today — Transit says that the obligation to pay interest has not yet matured.
We faced a similar question of entitlement to interest in Bebchick 777.145 There we decided that
the fair and appropriate date from which to accrue interest [is] ... the day on which Bebchick II was decided. In that decision the court decided for the first time that Transit had earned excess monies on prior fares which should be paid into the riders’ fund — overturning a contrary Commission ruling.146
Similarly our DCC decisions marked the turning point in the litigation now before us, for we there held for the first time that appreciation in the value of operating properties accruing while they were dedicated to the public service rightfully belonged to farepayers. Although the discussions in those cases did not reach the precise amount of restitution, they did set the maximum to which farepayers would be entitled.147 Consequently, we hold that interest on the amount of restitution ultimately awarded in this case should run from June 28,1973, the date of our decisions in DCC I and DCC II. Interest from that date is fully in order because of the substantial depletion in the value of money wrought by inflation, and the need to forestall unjust enrichment of Transit and to assist the effort to make the farepayers as whole as possible. Since, however, Transit did not know prior to issuance of these decisions that the fares authorized in Orders Nos. 773 and 1052 were improper, we decline to hold it responsible for interest before that date.
We must next determine the rate at which interest should be set, and find that the parties have provided little help on this issue. BUF suggests that we use the Consumer Price Index in order to “give [the farepayers] back today the economic equivalent of what was unlawfully taken from them.” 148 DCC urges us to employ “such rate as [we] deem appropriate under the criteria ... announced in Bebchick III.”149 Transit concentrates solely upon its denial of liability for prejudgment interest and fails to recommend any appropriate rate.150
In Bebchick III, we adopted an interest rate of 7.1 percent for the period from June 28, 1973, to December 19, 1974.151 This rate, proposed in that proceeding by the Bebchick group, was based upon the Consumer Price Index and the prime rate of a local bank,152 and we believe that it would be fair and equitable to use that rate in this proceeding as well. December 19, 1974, was the date on which monies now to be used for the farepayers’ restitution were deposited in a bank account under judicial [421]*421control,153 and in Bebchick III we ruled that interest from that date onward should be allowed at the rate earned by the monies in that account.154 Although no deposit arrangement was made in the DCC cases, we think the rate of interest allowed the Beb-chick group would be appropriate in the case at bar. We are guided in this connection by the American Law Institute’s suggestion that “a person owing restitution in money should make restitution as if he had invested the sum so owed.”155 The money in the court-held account is invested conservatively at minimum risk, and we are convinced that the rate may appropriately be adopted here. On remand, the Commission must calculate prejudgment interest accordingly.
III. Costs and Fees
We must now determine who must bear the expenses incurred by the Commission in connection with the remand proceedings already conducted. As we discussed in Bebchick III, the Commission initially assessed against Transit the costs in the Beb-chick and DCC disputes, and collected in advance approximately $200,000 from Transit to cover the Commission’s expenses on remand.156 Upon completion of those proceedings, however, the Commission concluded that Transit should bear none of the costs of the remand, and ruled that Transit was entitled to recover not only the $200,-000 previously collected from it for expenses of the Commission but also all of Transit’s own expenses.157 The Commission felt that the remand proceedings were essentially continuations of the prior rate-making proceedings, the costs of which fa-repayers are generally required to bear, and that the expenses on remand should be levied against the farepayers’ award of restitution.158
In Bebchick III, we upheld the initial assessment of the Commission’s costs against Transit, but reversed the decision contemplating reimbursement by farepay-ers for Transit’s own costs.159 We noted that while the Compact permitted the costs of ratemaking to be borne by farepayers, it also provided that “[a]H reasonable expenses of any investigation, or other proceeding of any nature, conducted by the Commission, of or concerning any carrier, and all expenses of any litigation, including appeals, arising [therefrom] shall be borne by such carrier.” 160 Because the remand in Bebchick III placed the Commission in a role not envisioned by the Compact — that of special master for the court, not rate-maker — the question of cost allocation was “not one of the Commission’s authority but of the court’s own judgment.”161 Accordingly, we concluded that the Bebchick group should not bear the expenses of either Transit or the Commission.
An examination of the variant circumstances surrounding the remand in the DCC cases, however, leads us to depart from our holding in Bebchick III with respect to the Commission’s own costs. In Bebchick III, we were influenced by the fact that “the remand was largely unnecessary. Transit rejected figures which it later accepted on the remand, and ... part of the Commission’s activities did not require any further hearings at all.” 162 Here, on the contrary, the immense value of the remand proceedings has been fully proven. The Commission, compliably with our in[422]*422structions in the DCC decisions, hired experts, compiled testimony and exhibits, commissioned studies, analyzed the massive record data and reported meaningfully its findings and conclusions to us. From this heavy investment of Commission time and labor, the farepayers and the court alike have benefited greatly. In keeping with the rationale of Bebchick III, we hold that the Commission’s costs on the last-conducted remand in these cases are to be paid from the fund for restitution. The exact amount of these costs will have to be calculated by the Commission, as the data before us163 do not demarcate the expenses in the DCC remands from those incurred in the remand from Bebchick II.
As to Transit’s costs, however, we cannot accept the Commission’s conclusion that they too should be paid out of the fund for restitution. Each participant before the Commission has sought to serve its own discrete interests, and we think it equitable to require each to pay its own way. Fairness thus dictates that each should bear its own expenses in connection with the remand.164
Finally, we reach an issue of attorneys’ fees. Prior to oral argument, we requested fee applications from petitioners,165 then assuming that today’s decision would mark the resolution of all controversies remaining. As still another remand to the Commission is necessary, we deem it best to defer consideration of awards of attorneys’ fees until ultimate disposition of these cases by this court. We will request supplemental fee applications at the appropriate time, and we do not ask the Commission to tackle the question of attorneys’ fees on remand.
IV. Conclusion
It is with much regret that once more we must remand to the Commission. We are, of course, fully aware of the duration of this litigation, but we lack the data needed for computation of the precise amount of restitution to be awarded to farepayers.
In an effort to minimize confusion and expedite the remand proceedings, we summarize the Commission’s remaining tasks. First, in calculating the gain through value appreciation on the Fourth Street Shop and the Southern Carhouse, the actual 1959 selling price must be substituted for the appraiser’s estimate.166 No deduction for a brokerage fee may be allowed,167 and these properties are to be treated like all others involved for the purpose of estimating capital gains taxes.168 Second, the capital gains taxes on all properties must be recalculated by resort to the methodology approved in Bebchick 7//.169 Third, the Commission must ensure that the total amount of restitution does not exceed the total of the fare excesses purportedly authorized by the orders under review in these cases.170 Fourth, the Commission must reduce the net gain on the Fourth Street Shop and Southern Carhouse by $613,-661.28 to compensate for profits already allocated to farepayers,171 and must subtract $283,869 for cost-of-living expenditures from the total amount of restitution.172 The Commission must then calculate interest from June 28, 1973, at the rate we have prescribed.173 Finally, the Commission’s expenses on the prior DCC re[423]*423mands, as well as those on the remand we order today, must be subtracted from the restitution award.174
When the remand proceedings are completed, the Commission will report the results to this court. At that time, the court will entertain any objections to the proceedings on remand, suggestions for distribution of the restitutionary fund, and applications for attorneys’ fees.
So ordered.