(Slip Opinion)              OCTOBER TERM, 2012                                       1

                                       Syllabus

         NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
       being done in connection with this case, at the time the opinion is issued.
       The syllabus constitutes no part of the opinion of the Court but has been
       prepared by the Reporter of Decisions for the convenience of the reader.
       See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.


SUPREME COURT OF THE UNITED STATES

                                       Syllabus

  PPL CORP. ET AL. v. COMMISSIONER OF INTERNAL 

                       REVENUE


CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
                  THE THIRD CIRCUIT

     No. 12–43. Argued February 20, 2013—Decided May 20, 2013
In 1997, the United Kingdom (U. K.), newly under Labour Party rule,
  imposed a one-time “windfall tax” on 32 U. K. companies privatized
  between 1984 and 1996 by the Conservative government. The com-
  panies had been sold to private parties through an initial sale of
  shares, known as a “flotation.” Some of the companies were required
  to continue providing services for a fixed period at the same rates
  they had offered under government control. Many of those companies
  became dramatically more efficient and earned substantial profits in
  the process.
     Petitioner PPL Corporation (PPL), part owner of a privatized U. K.
  company subject to the windfall tax, claimed a credit for its share of
  the bill in its 1997 federal income-tax return, relying on Internal
  Revenue Code §901(b)(1), which states that any “income, war profits,
  and excess profits taxes” paid overseas are creditable against U. S.
  income taxes. Treasury Regulation §1.901–2(a)(1) interprets this sec-
  tion to mean that a foreign tax is creditable if its “predominant char-
  acter” “is that of an income tax in the U. S. sense.” The Commission-
  er of Internal Revenue (Commissioner) rejected PPL’s claim, but the
  Tax Court held that the U. K. windfall tax was creditable for U. S.
  tax purposes under §901. The Third Circuit reversed.
Held: The U. K. tax is creditable under §901. Pp. 4–14.
    (a) Treasury Regulation §1.901–2, which codifies longstanding doc-
 trine dating back to Biddle v. Commissioner, 302 U. S. 573, 578–579
 (1938), provides the relevant legal standard. First, a tax’s “predomi-
 nant character,” or the normal manner in which a tax applies, is con-
 trolling. See id., at 579. Thus, a foreign tax that operates as an in-
 come, war profits, or excess profits tax for most taxpayers is generally
2                     PPL CORP. v. COMMISSIONER

                                    Syllabus

    creditable. Second, foreign tax creditability depends not on the way a
    foreign government characterizes its tax but on whether the tax, if
    enacted in the U. S., would be an income, war profits, or excess prof-
    its tax. See §1.901–2(a)(1)(ii). Giving further form to these princi-
    ples, §1.901–2(a)(3)(i) explains that a foreign tax’s predominant char-
    acter is that of a U. S. income tax “[i]f . . . the foreign tax is likely to
    reach net gain in the normal circumstances in which it applies.”
    Three tests set forth in the regulations provide guidance in making
    this assessment, see §1.901–2(b)(1). The tests indicate that net gain
    consists of realized gross receipts reduced by significant costs and ex-
    penses attributable to such gross receipts, in combination known as
    net income. A foreign tax that reaches net income, or profits, is cred-
    itable. Pp. 4–7.
       (b) The U. K. windfall tax’s predominant character is that of an ex-
    cess profits tax, a category of income tax in the U. S. sense. The La-
    bour government’s conception of “profit-making value” as a backward-
    looking analysis of historic profits is not a typical valuation
    method. Rather, it is a tax on realized net income disguised as a
    tax on the difference between two values, one of which is a fictitious
    value calculated using an imputed price-to-earnings ratio. The sub-
    stance of the windfall tax confirms this conclusion. When rear-
    ranged, the U. K’s formula demonstrates that the windfall tax is eco-
    nomically equivalent to the difference between the profits each
    company actually earned and the amount the Labour government be-
    lieved it should have earned given its flotation value. For most of the
    relevant companies, the U. K. formula’s substantive effect was to im-
    pose a 51.71 percent tax on all profits above a threshold, a classic ex-
    cess profits tax. The Commissioner claims that any algebraic rear-
    rangement is improper because U. S. courts must take the foreign tax
    rate as written and accept whatever tax base the foreign tax purports
    to adopt. But such a rigid construction cannot be squared with the
    black-letter principle that “tax law deals in economic realities, not le-
    gal abstractions.” Commissioner v. Southwest Exploration Co., 350
    U. S. 308, 315. Given the artificiality of the U. K.’s calculation meth-
    od, this Court follows substance over form and recognizes that the
    windfall tax is nothing more than a tax on actual profits above a
    threshold. Pp. 7–11.
       (c) The Commissioner’s additional arguments in support of his po-
    sition are similarly unpersuasive. Pp. 11–14.
665 F. 3d 60, reversed.

  THOMAS, J., delivered the opinion for               a   unanimous      Court.
SOTOMAYOR, J., filed a concurring opinion.
                       Cite as: 569 U. S. ____ (2013)                              1

                            Opinion of the Court

    NOTICE: This opinion is subject to formal revision before publication in the
    preliminary print of the United States Reports. Readers are requested to
    notify the Reporter of Decisions, Supreme Court of the United States, Wash­
    ington, D. C. 20543, of any typographical or other formal errors, in order
    that corrections may be made before the preliminary print goes to press.


SUPREME COURT OF THE UNITED STATES
                                  _________________

                                   No. 12–43
                                  _________________


PPL CORPORATION AND SUBSIDIARIES, PETITION-
 ERS v. COMMISSIONER OF INTERNAL REVENUE
 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
            APPEALS FOR THE THIRD CIRCUIT
                                [May 20, 2013]

   JUSTICE THOMAS delivered the opinion of the Court.
   In 1997, the United Kingdom (U. K.) imposed a one-time
“windfall tax” on 32 U. K. companies privatized between
1984 and 1996. This case addresses whether that tax
is creditable for U. S. tax purposes. Internal Revenue Code
§901(b)(1) states that any “income, war profits, and excess
profits taxes” paid overseas are creditable against U. S.
income taxes. 26 U. S. C. §901(b)(1). Treasury Regula­
tions interpret this section to mean that a foreign tax is
creditable if its “predominant character” “is that of an
income tax in the U. S. sense.” Treas. Reg. §1.901–
2(a)(1)(ii), 26 CFR §1.901–2(a)(1) (1992). Consistent with
precedent and the Tax Court’s analysis below, we apply
the predominant character test using a commonsense
approach that considers the substantive effect of the tax.
Under this approach, we hold that the U. K. tax is credit­
able under §901 and reverse the judgment of the Court of
Appeals for the Third Circuit.
                          I
                          A
  During the 1980’s and 1990’s, the U. K.’s Conservative
2                PPL CORP. v. COMMISSIONER

                      Opinion of the Court

Party controlled Parliament and privatized a number of
government-owned companies. These companies were
sold to private parties through an initial sale of shares,
known as a “flotation.” As part of privatization, many com­
panies were required to continue providing services at the
same rates they had offered under government control
for a fixed period, typically their first four years of private
operation. As a result, the companies could only increase
profits during this period by operating more efficiently.
Responding to market incentives, many of the companies
became dramatically more efficient and earned substantial
profits in the process.
   The U. K.’s Labour Party, which had unsuccessfully
opposed privatization, used the companies’ profitability as
a campaign issue against the Conservative Party. In part
because of campaign promises to tax what it characterized
as undue profits, the Labour Party defeated the Conserva­
tive Party at the polls in 1997. Prior to coming to power,
Labour Party leaders hired accounting firm Arthur Ander­
sen to structure a tax that would capture excess, or “wind­
fall,” profits earned during the initial years in which the
companies were prohibited from increasing rates. Par­
liament eventually adopted the tax, which applied only to
the regulated companies that were prohibited from raising
their rates. See Finance (No. 2) Act, 1997, ch. 58, pt. I,
cls. 1 and 2(5) (Eng.) (U. K. Windfall Tax Act). It imposed
a 23 percent tax on any “windfall” earned by such compa­
nies. Id., cl. 1(2). A separate schedule “se[t] out how to
quantify the windfall from which a company was benefit­
ting.” Id., cl. 1(3). See id., sched. 1.
   In the proceedings below, the parties stipulated that the
following formula summarizes the tax imposed by the
Labour Party:
                                     P
               Tax = 23%	 ൤൬365 × ൬ ൰ × 9൰ − FV൨
                                     D
D equals the number of days a company was subject to
                    Cite as: 569 U. S. ____ (2013)                   3

                         Opinion of the Court

rate regulation (also known as the “initial period”), P
equals the total profits earned during the initial period,
and FV equals the flotation value, or market capitalization
value after sale. For 27 of the 32 companies subject to
the tax, the number of days in the initial period was 1,461
days (or four years). Of the remaining five companies, one
had no tax liability because it did not earn any windfall
profits. Three had initial periods close to four years
(1,463, 1,456, and 1,380 days). The last was privatized
shortly before the Labour Party took power and had an
initial period of only 316 days.
   The number 9 in the formula was characterized as a
price-to-earnings ratio and was selected because it repre­
sented the lowest average price-to-earnings ratio of the 32
companies subject to the tax during the relevant period.1
See id., sched. 1, §1, cl. 2(3); Brief for Respondent 7. The
statute expressly set its value, and that value was the
same for all companies. U. K. Windfall Tax Act, sched. 1,
§1, cl. 2(3). The only variables that changed in the wind­
fall tax formula for all the companies were profits (P) and
flotation value (FV); the initial period (D) varied for only a
few of the companies subject to the tax. The Labour gov­
ernment asserted that the term [365 × (P ⁄ D) × 9] repre­
sented what the flotation value should have been given the
assumed price-to-earnings ratio of 9. Thus, it claimed
(and the Commissioner here reiterates) that the tax was
simply a 23 percent tax on the difference between what
the companies’ flotation values should have been and what
they actually were.
                        B
  Petitioner PPL Corporation (PPL) was an owner,
——————
  1A  price-to-earnings ratio “is defined as the stock price divided by
annual earnings per share. It is typically calculated by dividing the
current stock price by the sum of the previous four quarters of earn­
ings.” 3 New Palgrave Dictionary of Money & Finance 176 (1992).
4                  PPL CORP. v. COMMISSIONER

                         Opinion of the Court

through a number of subsidiaries, of 25 percent of South
Western Electricity plc, 1 of 12 government-owned elec­
tric companies that were privatized in 1990 and that were
subject to the tax. See 135 T. C. 304, 307, App. (2010)
(diagram of PPL corporate structure in 1997). South
Western Electricity’s total U. K. windfall tax burden was
£90,419,265. In its 1997 federal income-tax return, PPL
claimed a credit under §901 for its share of the bill. The
Commissioner of Internal Revenue (Commissioner) rejected
the claim, but the Tax Court held that the U. K. wind-
fall tax was creditable for U. S. tax purposes under §901.
See id., at 342. The Third Circuit reversed. 665 F. 3d 60,
68 (2011). We granted certiorari, 568 U. S. ___ (2012), to
resolve a Circuit split concerning the windfall tax’s cred­
itability under §901. Compare 665 F. 3d, at 68, with
Entergy Corp. & Affiliated Subsidiaries v. Commissioner,
683 F. 3d 233, 239 (CA5 2012).
                               II
  Internal Revenue Code §901(b)(1) provides that “[i]n the
case of . . . a domestic corporation, the amount of any
income, war profits, and excess profits taxes paid or ac­
crued during the taxable year to any foreign country or to
any possession of the United States” shall be creditable.2
Under relevant Treasury Regulations, “[a] foreign levy is
an income tax if and only if . . . [t]he predominant charac­
ter of that tax is that of an income tax in the U. S. sense.”
26 CFR §1.901–2(a)(1). The parties agree that Treasury
Regulation §1.901–2 applies to this case. That regulation
codifies longstanding doctrine dating back to Biddle v.
——————
  2 Prior to enactment of what is now §901, income earned overseas was

subject to taxes not only in the foreign country but also in the United
States. See Burnet v. Chicago Portrait Co., 285 U. S. 1, 7 (1932). The
relevant text making “income, war-profits and excess-profits taxes”
creditable has not changed since 1918. See Revenue Act of 1918,
§§222(a)(1), 238(a), 40 Stat. 1073, 1080.
                  Cite as: 569 U. S. ____ (2013)             5

                      Opinion of the Court

Commissioner, 302 U. S. 573, 578–579 (1938), and pro­
vides the relevant legal standard.
   The regulation establishes several principles relevant to
our inquiry. First, the “predominant character” of a tax,
or the normal manner in which a tax applies, is control­
ling. See id., at 579 (“We are here concerned only with
the ‘standard’ or normal tax”). Under this principle, a for­
eign tax that operates as an income, war profits, or excess
profits tax in most instances is creditable, even if it may
affect a handful of taxpayers differently. Creditability is
an all or nothing proposition. As the Treasury Regula­
tions confirm, “a tax either is or is not an income tax, in its
entirety, for all persons subject to the tax.” 26 CFR
§1.901–2(a)(1).
   Second, the way a foreign government characterizes its
tax is not dispositive with respect to the U. S. creditability
analysis. See §1.901–2(a)(1)(ii) (foreign tax creditable if
predominantly “an income tax in the U. S. sense”). In
Biddle, the Court considered the creditability of certain
U. K. taxes on stock dividends under the substantively
identical predecessor to §901. The Court recognized that
“there is nothing in [the statute’s] language to suggest
that in allowing the credit for foreign tax payments, a
shifting standard was adopted by reference to foreign
characterizations and classifications of tax legislation.”
302 U. S., at 578–579. See also United States v. Goodyear
Tire & Rubber Co., 493 U. S. 132, 145 (1989) (noting in
interpreting 26 U. S. C. §902 that Biddle is particularly
applicable “where a contrary interpretation would leave”
tax interpretation “to the varying tax policies of foreign
tax authorities”); Heiner v. Mellon, 304 U. S. 271, 279, and
n. 7 (1938) (state-law definitions generally not controlling
in federal tax context). Instead of the foreign govern­
ment’s characterization of the tax, the crucial inquiry is
the tax’s economic effect. See Biddle, supra, at 579 (in­
quiry is “whether [a tax] is the substantial equivalent of
6                   PPL CORP. v. COMMISSIONER

                           Opinion of the Court

payment of the tax as those terms are used in our own
statute”). In other words, foreign tax creditability depends
on whether the tax, if enacted in the U. S., would be an
income, war profits, or excess profits tax.
   Giving further form to these principles, Treasury Regu­
lation §1.901–2(a)(3)(i) explains that a foreign tax’s pre­
dominant character is that of a U. S. income tax “[i]f . . .
the foreign tax is likely to reach net gain in the normal
circumstances in which it applies.” The regulation then
sets forth three tests for assessing whether a foreign tax
reaches net gain. A tax does so if, “judged on the basis of
its predominant character, [it] satisfies each of the realiza­
tion, gross receipts, and net income requirements set forth
in paragraphs (b)(2), (b)(3) and (b)(4), respectively, of this
section.” §1.901–2(b)(1).3 The tests indicate that net gain
(also referred to as net income) consists of realized gross
receipts reduced by significant costs and expenses attrib­
utable to such gross receipts. A foreign tax that reaches

——————
   3 The relevant provisions provide as follows:

“A foreign tax satisfies the realization requirement if, judged on the
basis of its predominant character, it is imposed—(A) Upon or subse­
quent to the occurrence of events (‘realization events’) that would result
in the realization of income under the income tax provisions of the
Internal Revenue Code.” 26 CFR §1.901–2(b)(2)(i).
    “A foreign tax satisfies the gross receipts requirement if, judged on the
basis of its predominant character, it is imposed on the basis of—(A)
Gross receipts; or (B) Gross receipts computed under a method that is
likely to produce an amount that is not greater than fair market value.”
§1.901–2(b)(3)(i).
    “A foreign tax satisfies the net income requirement if, judged on the
basis of its predominant character, the base of the tax is computed by
reducing gross receipts . . . to permit—(A) Recovery of the significant
costs and expenses (including significant capital expenditures) at­
tributable, under reasonable principles, to such gross receipts; or (B)
Recovery of such significant costs and expenses computed under a
method that is likely to produce an amount that approximates, or is
greater than, recovery of such significant costs and expenses.” §1.901–
2(b)(4)(i).
                  Cite as: 569 U. S. ____ (2013)            7

                      Opinion of the Court

net income, or profits, is creditable.
                               III
                                A
   It is undisputed that net income is a component of the
U. K.’s “windfall tax” formula. See Brief for Respondent
23 (“The windfall tax takes into account a company’s prof­
its during its four-year initial period”). Indeed, annual
profit is a variable in the tax formula. U. K. Windfall Tax
Act, sched. 1, §1, cls. 2(2) and 5. It is also undisputed that
there is no meaningful difference for our purposes in the
accounting principles by which the U. K. and the U. S.
calculate profits. See Brief for Petitioners 47. The dis­
agreement instead centers on how to characterize the tax
formula the Labour Party adopted.
   The Third Circuit, following the Commissioner’s lead,
believed it could look no further than the tax formula that
the Parliament enacted and the way in which the Labour
government characterized it. Under that view, the wind­
fall tax must be considered a tax on the difference between
a company’s flotation value (the total amount investors
paid for the company when the government sold it) and
an imputed “profit-making value,” defined as a company’s
“average annual profit during its ‘initial period’ . . . times
9, the assumed price-to-earnings ratio.” 665 F. 3d, at 65.
So characterized, the tax captures a portion of the differ­
ence between the price at which each company was sold
and the price at which the Labour government believed
each company should have been sold given the actual
profits earned during the initial period. Relying on this
characterization, the Third Circuit believed the windfall
tax failed at least the Treasury Regulation’s realization
and gross receipts tests because it reached some artificial
form of valuation instead of profits. See id., at 67, and
n. 3.
   In contrast, PPL’s position is that the substance of the
8               PPL CORP. v. COMMISSIONER

                      Opinion of the Court

windfall tax is that of an income tax in the U. S. sense.
While recognizing that the tax ostensibly is based on the
difference between two values, it argues that every “vari­
able” in the windfall tax formula except for profits and
flotation value is fixed (at least with regard to 27 of the 32
companies). PPL emphasizes that the only way the La­
bour government was able to calculate the imputed “profit­
making value” at which it claimed companies should have
been privatized was by looking after the fact at the actual
profits earned by each company. In PPL’s view, it matters
not how the U. K. chose to arrange the formula or what it
claimed to be taxing, because a tax based on profits above
some threshold is an excess profits tax, regardless of how
it is mathematically arranged or what labels foreign law
places on it. PPL, thus, contends that the windfall taxes it
paid meet the Treasury Regulation’s tests and are credit­
able under §901.
   We agree with PPL and conclude that the predominant
character of the windfall tax is that of an excess profits
tax, a category of income tax in the U. S. sense. It is
important to note that the Labour government’s concep­
tion of “profit-making value” as a backward-looking analy­
sis of historic profits is not a recognized valuation method;
instead, it is a fictitious value calculated using an imputed
price-to-earnings ratio. At trial, one of PPL’s expert wit­
nesses explained that “ ‘9 is not an accurate P/E multiple,
and it is not applied to current or expected future earn­
ings.’ ” 135 T. C., at 326, n. 17 (quoting testimony). In­
stead, the windfall tax is a tax on realized net income
disguised as a tax on the difference between two values,
one of which is completely fictitious. See App. 251, Report
¶1.7 (“[T]he value in profit making terms described in the
wording of the act . . . is not a real value: it is rather a
construct based on realised profits that would not have
been known at the date of privatisation”).
   The substance of the windfall tax confirms the accuracy
                       Cite as: 569 U. S. ____ (2013)                       9

                            Opinion of the Court

of this observation. As already noted, the parties stipulated
that the windfall tax could be calculated as follows:
                                    P
                Tax = 23%	 ൤൬365 × ൬ ൰ × 9൰ − FV൨
                                    D
This formula can be rearranged algebraically to the follow­
ing formula, which is mathematically and substantively
identical:4
               (365 × 9 × 23%)                  D
        Tax = ൤               ൨ × ൜P − ൤FV ×           	൨ൠ
                      D                      (365 × 9)
The next step is to substitute the actual number of days
for D. For 27 of the 32 companies subject to the windfall
tax, the number of days was identical, 1,461 (or four
years). Inserting that amount for D in the formula yields
the following:
                (365 × 9 × 23%)                 1,461

         Tax = ൤               ൨ × ൜P − ൤FV ×           	൨ൠ

                     1,461                    (365 × 9)
Simplifying the formula by multiplying and dividing num­
bers reduces the formula to:
                                   FV
            Tax = 51.71% × ൤P − 	 ൬ ൰ × 4.0027൨
                                    9
As noted, FV represents the value at which each company
was privatized. FV is then divided by 9, the arbitrary
“price-to-earnings ratio” applied to every company. The
——————
  4 The rearrangement requires only basic algebraic manipulation.

First, because order of operations does not matter for multiplication
and division, the formula is rearranged to the following:
                                              ୔
                      Tax = 23%	 ቂ൬365 × 9 × ቀୈቁ൰ − FVቃ
                                                              (ଷ଺ହ×ଽ)
Next, everything outside the brackets is multiplied by ቂ                ቃ,	and
                                                                ୈ
                                                                        ୈ
everything inside the brackets is multiplied by the inverse, ቂ(ଷ଺ହ×ଽ)ቃ.
The effect is the same as multiplication by the number one (since
   (ଷ଺ହ×ଽ)       ୈ
ቄቂ         ቃ ×	ቂ   ቃቅ = 	1). That multiplication yields the formula in the
    ୈ       (ଷ଺ହ×ଽ)
text.
10              PPL CORP. v. COMMISSIONER

                      Opinion of the Court

economic effect is to convert flotation value into the profits
a company should have earned given the assumed price­
to-earnings ratio. See 135 T. C., at 327 (“ ‘In effect, the
way the tax works is to say that the amount of profits
you’re allowed in any year before you’re subject to tax is
equal to one-ninth of the flotation price. After that, profits
are deemed excess, and there is a tax’ ” (quoting testimony
from the treasurer of South Western Electricity plc)). The
annual profits are then multiplied by 4.0027, giving the
total “acceptable” profits (as opposed to windfall profit)
that each company’s flotation value entitled it to earn
during the initial period given the artificial price-to­
earnings ratio of 9. This fictitious amount is finally sub­
tracted from actual profits, yielding the excess profits,
which were taxed at an effective rate of 51.71 percent.
   The rearranged tax formula demonstrates that the
windfall tax is economically equivalent to the difference
between the profits each company actually earned and the
amount the Labour government believed it should have
earned given its flotation value. For the 27 companies
that had 1,461-day initial periods, the U. K. tax formula’s
substantive effect was to impose a 51.71 percent tax on all
profits earned above a threshold. That is a classic excess
profits tax. See, e.g., Act of Mar. 3, 1917, ch. 159, Tit. II,
§201, 39 Stat. 1000 (8 percent tax imposed on excess prof­
its exceeding the sum of $5,000 plus 8 percent of invested
capital).
   Of course, other algebraic reformulations of the windfall
tax equation are possible. See 665 F. 3d, at 66; Brief for
Anne Alstott et al. as Amici Curiae 21–23 (Alstott Brief).
The point of the reformulation is not that it yields a par­
ticular percentage (51.75 percent for most of the compa­
nies). Rather, the algebraic reformulations illustrate the
economic substance of the tax and its interrelationship
with net income.
   The Commissioner argues that any algebraic rear­
                 Cite as: 569 U. S. ____ (2013)           11

                     Opinion of the Court

rangement is improper, asserting that U. S. courts must
take the foreign tax rate as written and accept whatever
tax base the foreign tax purports to adopt. Brief for Re­
spondent 28. As a result, the Commissioner claims that
the analysis begins and ends with the Labour govern­
ment’s choice to characterize its tax base as the difference
between “profit-making value” and flotation value. Such a
rigid construction is unwarranted. It cannot be squared
with the black-letter principle that “tax law deals in eco­
nomic realities, not legal abstractions.” Commissioner v.
Southwest Exploration Co., 350 U. S. 308, 315 (1956).
Given the artificiality of the U. K.’s method of calculating
purported “value,” we follow substance over form and
recognize that the windfall tax is nothing more than a tax
on actual profits above a threshold.
                              B
   We find the Commissioner’s other arguments unpersua­
sive as well. First, the Commissioner attempts to buttress
the argument that the windfall tax is a tax on value by
noting that some U. S. gift and estate taxes use actual,
past profits to estimate value. Brief for Respondent 17–18
(citing 26 CFR §20.2031–3 (2012) and 26 U. S. C. §2032A).
This argument misses the point. In the case of valuation
for gift and estate taxes, past income may be used to esti­
mate future income streams. But, it is future revenue­
earning potential, reduced to market value, that is subject
to taxation. The windfall profits tax, by contrast, undis­
putedly taxed past, realized net income alone.
   The Commissioner contends that the U. K. was not
trying to establish valuation as of the 1997 date on which
the windfall tax was enacted but instead was attempting
to derive a proper flotation valuation as of each company’s
flotation date. Brief for Respondent 21. The Commissioner
asserts that there was no need to estimate future in-
come (as in the case of the gift or estate recipient) because
12              PPL CORP. v. COMMISSIONER

                     Opinion of the Court

actual revenue numbers for the privatized companies were
available. Ibid. That argument also misses the mark. It
is true, of course, that the companies might have been
privatized at higher flotation values had the government
recognized how efficient—and thus how profitable—the
companies would become. But, the windfall tax requires
an underlying concept of value (based on actual ex post
earnings) that would be alien to any valuer. Taxing ac­
tual, realized net income in hindsight is not the same as
considering past income for purposes of estimating future
earning potential.
   The Commissioner’s reliance on Example 3 to the
Treasury Regulation’s gross receipts test is also misplaced.
Id., at 37–38; 26 CFR §1.901–2(b)(3)(ii), Ex. 3. That ex­
ample posits a petroleum tax in which “gross receipts from
extraction income are deemed to equal 105 percent of the
fair market value of petroleum extracted. This computa­
tion is designed to produce an amount that is greater than
the fair market value of actual gross receipts.” Ibid.
Under the example, a tax based on inflated gross receipts
is not creditable.
   The Third Circuit believed that the same type of alge­
braic rearrangement used above could also be used to
rearrange a tax imposed on Example 3. It hypothesized:
     “Say that the tax rate on the hypothetical extraction
     tax is 20%. It is true that a 20% tax on 105% of re­
     ceipts is mathematically equivalent to a 21% tax on
     100% of receipts, the latter of which would satisfy the
     gross receipts requirement. PPL proposes that we
     make the same move here, increasing the tax rate
     from 23% to 51.75% so that there is no multiple of re­
     ceipts in the tax base. But if the regulation allowed
     us to do that, the example would be a nullity. Any tax
     on a multiple of receipts or profits could satisfy the
     gross receipts requirement, because we could reduce
                      Cite as: 569 U. S. ____ (2013)                13

                          Opinion of the Court

     the starting point of its tax base to 100% of gross
     receipts by imagining a higher tax rate.” 665 F. 3d,
     at 67.
The Commissioner reiterates the Third Circuit’s argu­
ment. Brief for Respondent 37–38.
   There are three basic problems with this approach. As
the Fifth Circuit correctly recognized, there is a difference
between imputed and actual receipts. “Example 3 hypoth­
esizes a tax on the extraction of petroleum where the
income value of the petroleum is deemed to be . . . deliber­
ately greater than actual gross receipts.” Entergy Corp.,
683 F. 3d, at 238. In contrast, the windfall tax depends
on actual figures. Ibid. (“There was no need to calculate
imputed gross receipts; gross receipts were actually
known”). Example 3 simply addresses a different foreign
taxation issue.
   The argument also incorrectly equates imputed gross
receipts under Example 3 with net income. See 665 F. 3d,
at 67 (“[a]ny tax on a multiple of receipts or profits”). As
noted, a tax is creditable only if it applies to realized gross
receipts reduced by significant costs and expenses attribut-
able to such gross receipts. 26 CFR §1.901–2(b)(4)(i). A
tax based solely on gross receipts (like the Third Circuit’s
analysis) would be noncreditable because it would fail the
Treasury Regulation’s net income requirement.
   Finally, even if expenses were subtracted from imputed
gross receipts before a tax was imposed, the effect of in­
flating only gross receipts would be to inflate revenue
while holding expenses (the other component of net in­
come) constant. A tax imposed on inflated income minus
actual expenses is not the same as a tax on net income.5
——————
  5 Mathematically, the Third Circuit’s hypothetical was incomplete. It
should have been:
            20% [ 105% (Gross Receipts) − Expenses ] = Tax
But 105% of gross receipts minus expenses is not net income. Thus, the
14                 PPL CORP. v. COMMISSIONER

                         Opinion of the Court

  For these reasons, a tax based on imputed gross receipts
is not creditable. But, as the Fifth Circuit explained in
rejecting the Third Circuit’s analysis, Example 3 is “faci­
ally irrelevant” to the analysis of the U. K. windfall tax,
which is based on true net income. Entergy Corp., supra,
at 238.6
                         *     *    *
   The economic substance of the U. K. windfall tax is that
of a U. S. income tax. The tax is based on net income, and
the fact that the Labour government chose to characterize
it as a tax on the difference between two values is not
dispositive under Treasury Regulation §1.901–2. There­
fore, the tax is creditable under §901.
   The judgment of the Third Circuit is reversed.

                                                     It is so ordered.




——————
20% tax is not a tax on net income and is not creditable.
  6 An amici brief argues that because two companies had initial peri­

ods substantially shorter than four years, the predominant character of
the U. K. windfall tax was not a tax on income in the U. S. sense. See
Alstott Brief 29 (discussing Railtrack Group plc and British Energy
plc). The argument amounts to a claim that two outliers changed the
predominant character of the U. K. tax. See 135 T. C. 304, 340, n. 33
(2010) (rejecting this view).
  The Commissioner admitted at oral argument that it did not preserve
this argument, a fact reflected in its briefing before this Court and in
the Third Circuit. See Tr. of Oral Arg. 35–36; Opening Brief for Appel­
lant and Reply Brief for Appellant in No. 11–1069 (CA3). We therefore
express no view on its merits.
                   Cite as: 569 U. S. ____ (2013)              1

                    SOTOMAYOR, J., concurring

SUPREME COURT OF THE UNITED STATES
                           _________________

                            No. 12–43
                           _________________


PPL CORPORATION AND SUBSIDIARIES, PETITION-
 ERS v. COMMISSIONER OF INTERNAL REVENUE
 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
            APPEALS FOR THE THIRD CIRCUIT
                          [May 20, 2013]

   JUSTICE SOTOMAYOR, concurring.
   The Court’s conclusion that the windfall tax is a creditable
excess profits tax under 26 U. S. C. §901(b)(1) depends on
two interrelated analytic moves: first, restricting the “predom-
inant character” analysis to those companies that shared an
“initial period” of rate regulation of 1,461 days; and second,
treating the tax’s initial period variable as fixed. See ante,
at 9–10. But there is a different way of looking at this
case. If the predominant character inquiry is expanded to
include      the     five   companies       that     had     dif-
ferent initial periods, especially those with much shorter
initial periods, it becomes impossible to rewrite the wind-
fall tax as an excess profits tax. Instead, it becomes clear
that the windfall tax is functionally a tax on value. But
because the Government took the position at oral argu-
ment that the predominant character inquiry should
disregard such “outlie[r]” companies, see Tr. of Oral Arg.
38–39, and this argument is therefore only pressed by
amici, Brief for Anne Alstott et al. as Amici Curiae 28–30
(hereinafter Alstott Brief), I reserve consideration of this
argument for another day and another context and join
the Court’s opinion.
                     *    *    *
  The Internal Revenue Code provides that “income, war
2                  PPL CORP. v. COMMISSIONER

                       SOTOMAYOR, J., concurring

profits, and excess profits taxes” paid to a foreign country
are creditable. 26 U. S. C. §901(b)(1). Whether a foreign
tax falls within one of these categories depends on whether
its “predominant character . . . is that of an income tax
in the U. S. sense.” 26 CFR §1.901–2(a)(1)(ii) (2010). As
the Court explains, there are three components to this in-
quiry, ante, at 4–7, but at its core the inquiry simply asks
whether a foreign tax resembles a typical income, war
profits, or excess profits tax, ante, at 6.
   Importantly, though, the relevant Treasury Regulations
also provide that a foreign tax “is or is not an income tax,
in its entirety, for all persons subject to the tax.” 26 CFR
§1.901–2(a)(1). One way to understand this language is
that for a tax to be classed as a creditable income tax,
its predominant character must be that of an income tax
with respect to “all persons subject to the tax.” Of course,
among the many persons subject to a tax, some may face
tax burdens different from the majority of affected taxpay-
ers. The challenge in applying predominant character
analysis will sometimes lie in determining whether and
how such outlier taxpayers affect the characterization of a
given tax.1
——————
  1 For example, some taxes may produce outliers that might suggest

that the tax is not an income tax, when in fact the tax is attempting
to reach net gain and therefore has the predominant character of an
income tax. This situation often arises when a tax relies on imperfect
estimates and assumptions in attempting to calculate net gain. Such a
tax strives to treat similarly situated taxpayers the same but fails to do
so only because the estimated component inadvertently affects some
taxpayers differently. A situation of this kind occurred in Texasgulf,
Inc. v. Commissioner, 172 F. 3d 209 (CA2 1999). In that case, a Cana-
dian mining tax did not permit taxpayers to deduct their specific
expenses, but did permit them to deduct a fixed “processing allowance.”
Id., at 211–213. The taxpayer argued that the tax was creditable
because the processing allowance was an attempt to reach net income,
gross income minus expenses, by using “ ‘a method that is likely to
produce an amount that approximates, or is greater than, recovery of
such significant costs and expenditures.’ ” Id., at 215 (quoting 26 CFR
                    Cite as: 569 U. S. ____ (2013)                   3

                      SOTOMAYOR, J., concurring

  The windfall tax at issue here exemplifies this problem.
As the Court notes, ante, at 2–3, the parties stipulated to
the following form of the windfall tax:
                                        ܲ
               ܶܽ‫ × %32 = ݔ‬൤൬365
×        × 9൰ − ‫ ܸܨ‬൨
                                        ‫ܦ‬
If the predominant character analysis is restricted to those
27 companies that share an identical initial period length,
then it makes sense to fix D at 1,461, as the Court does.
Ante, at 9–10. And from there, it is just a matter of basic
algebra, ante, at 9, and n. 4, to show that these companies’
tax liability is equal to total profits minus a threshold
amount (in this case, 44.47% of each company’s flotation
value) multiplied by a percentage-form tax rate: ܶܽ‫= ݔ‬
51.71% × [ܲ − (44.47% × ‫ .])ܸܨ‬See ante, at 9; Brief for
Petitioners 10. Because an excess profits tax is generally
a tax levied on the profits of a business beyond a particu-
lar threshold, see Wells, Legislative History of Excess
Profits Taxation in the United States in World Wars I and
II, 4 Nat. Tax J. 237, 243 (1951), it appears to follow that
the windfall tax can properly be characterized as an excess
profits tax.
   But not all of the 32 affected companies had an initial
——————
§1.901–2(b)(4)(i)(B) (1999)). To support its argument, the taxpayer
introduced empirical evidence that roughly 85% of companies facing
mining tax liability had nonrecoverable expenses less than the pro-
cessing allowance. Texasgulf, Inc., 172 F. 3d, at 215–216. The Court of
Appeals agreed with the taxpayer that the tax was a creditable income
tax because it was clear that the mining tax was attempting to reach
net income, albeit by using an estimate to calculate deductions. Id.,
at 216–217. This result is sensible: A company that happens to have
deductible expenses greater than the fixed amount set by the pro-
cessing allowance is not an instructive outlier regarding the mining
taxes predominant character. The mining tax is attempting to reach
that company’s net income, but fails to do only because it relies on an
approximate value for deductions.
4                  PPL CORP. v. COMMISSIONER

                      SOTOMAYOR, J., concurring

period length of 1,461 days; 5 of the companies had dif-
ferent initial periods. See App. 34, 39–41. When these
different initial period values are inserted into the formu-
lation proposed by PPL, two results follow. First, these
companies have tax rates different from the 51.71% rate
the Court calculates for the 27 other companies. Second,
their excess profits threshold also varies.
  For example, consider Railtrack Group, a clear outlier
with an initial period of 316 days. Inserting this value
into the stipulated formula yields the following:
                                         ܲ
              ܶܽ‫ × %32 = ݔ‬൤൬365
×           × 9൰ − ‫ ܸܨ‬൨
                                        316
Applying the Court’s algebra, this formula can be reduced
to the following: ܴ݈ܽ݅‫− ܲ[ × %01.932 = ݔܽܶ ݏ’݌ݑ݋ݎܩ ݇ܿܽݎݐ‬
(9.62% × ‫ 
 .]) ܸܨ‬Railtrack Group’s “effective” tax rate and
its excess profits threshold (239.10% and 9.62% respec-
tively) are very different from those companies with the
common initial period length of 1,461 days (51.71% and
44.47%). See ante, at 10. Railtrack Group is not alone in
this respect: four other companies also had tax rates and
excess profits thresholds that differed from the majority of
affected companies. See App. 34, 38–40.2
   Once these outlier companies are included in the cred-
itability analysis, it becomes clear that the windfall tax “is
not an income tax . . . for all persons” subject to it. 26 CFR
——————
  2 The figures for the other four companies are as follows: Powergen

plc, which had an initial period of 1,463 days had a tax rate of 51.64%
and an excess profits threshold of 44.54%, App. 38–39; National Power
plc, which had an initial period of 1,456 days, had a rate of 51.89% and
a threshold of 44.32%, id., at 39–40; Northern Ireland Electricity plc,
which had an initial period of 1,380 days, had a rate of 54.75% and a
threshold of 42.01%, id., at 40; and British Energy plc, which had an
initial period of 260 days, had a rate of 290.60% and a threshold of
7.91%, id., at 34. British Energy, however, did not end up having any
windfall tax liability. Id., at 33.
                     Cite as: 569 U. S. ____ (2013)                   5

                      SOTOMAYOR, J., concurring

§1.901–2(a)(1) (emphasis added). A typical income tax
applies a fixed percentage rate to a base income that
varies across taxpayers. An excess profits tax does the
same, but incorporates a threshold, which may or may not
vary across taxpayers, to exempt a portion of the base
from taxation. In contrast, here both of the rate and
threshold components vary from company to company
according to the D variable.3
   Seen through this lens, the windfall tax is really a tax
on average profits. See Alstott Brief 28–30. Under the
parties’ stipulated form of the windfall tax, each company
pays a fixed tax rate of 23% on a base that is calculated by
first multiplying a company’s daily average profits during
its initial period (i.e.,	(
 ‫ ,
)ܦ‬or total profits over the initial
                           ܲ/
period divided by the length of the initial period) by a fixed
price-to-earnings ratio; and then subtracting that com-
pany’s flotation value (‫ .) ܸܨ‬See ante, at 2. In practice, this
means that, for example, a company that earns $100
million over 1,461 days would pay approximately the same
amount of taxes as a company that has earned $25 million
over 365 days. These two companies would have almost
the same average profits. See Alstott Brief 28. This is not
how an income tax works.
   The difference between a tax on profits and tax on aver-
age profits is especially significant for properly character-
izing a tax such as the windfall tax. Average daily profits
multiplied by a price-to-earnings ratio, rather than being a
——————
  3 At oral argument, PPL contended that an excess profits tax in which

the excess profits threshold varies according to market capitalization
would also have an effective tax rate that varies across taxpayers but
remains creditable. Tr. of Oral Arg. 26–27. That might be true, but
that does not describe the situation here. In PPL’s hypothetical, any
shift in the effective tax rate depends on the profits threshold; Here,
under PPL’s version of the windfall tax, both the effective tax rate and
the profits threshold move proportionately to a company’s initial period
length.
6                  PPL CORP. v. COMMISSIONER

                      SOTOMAYOR, J., concurring

way of approximating income, is a way of approximating
value.4 See Thompson, A Lawyer’s Guide to Modern Val-
uation Techniques in Mergers and Acquisitions, 21 J.
Corp. L. 457, 532–533 (1996) (describing similar valuation
techniques using price-to-earnings ratios). Accordingly,
incorporating an outlier like Railtrack Group into the
predominant character analysis suggests that the windfall
tax is a tax on a company’s value. Railtrack Group and
the companies like it are not random outliers, Brief for
Petitioners 38, n. 3, but instead are critical pieces of data
for understanding how the tax actually functioned as a
matter of “economic realit[y].” Commissioner v. Southwest
Exploration Co., 350 U. S. 308, 315 (1956).
  This argument, however, rests on the premise that
because the relevant regulations state that “a tax either is
or is not an income tax, in its entirety, for all persons
subject to the tax,” 26 CFR §1.901–2(a)(1)(ii), a tax’s pre-
dominant character must be as an income tax for all tax-
payers. But if a tax only needs to be an income tax for
“a substantial number of taxpayers” and does not have to
“satisfy the predominant character test in its application
to all taxpayers,” Exxon Corp. v. Commissioner, 113 T. C.
338, 352 (1999), then this average profits argument cannot
get off the ground. Under this reading, the regulations tell
courts to treat outliers like Railtrack Group as flukes.
  At oral argument, the Government apparently rejected
the notion that “outliers” like Railtrack Group are relevant
to creditability analysis. See Tr. of Oral Arg. 35–39. The
Government also did not argue these outliers’ relevance
——————
   4 Petitioners suggested at oral argument that because some of the

outlier taxpayers may have been subject to a more favorable regulatory
regime in the wake of their privatization, their outsized tax rates are
less meaningful because they could recoup their windfall tax burdens.
See id., at 16–17. Even accepting the premise of this argument, it still
does not change that fact that in “substance,” ante, at 9, the tax func-
tioned as value tax for these companies.
                 Cite as: 569 U. S. ____ (2013)           7

                  SOTOMAYOR, J., concurring

before the Court of Appeals, ante, at 14, n. 6, and so this
argument, and the regulatory interpretation it depends
upon, has only been presented to this Court by amici, see
Alstott Brief 17–18, 28–30. We are not barred from con-
sidering statutory and regulatory interpretations raised in
an amicus brief, but we should be “reluctant to do so,”
Davis v. United States, 512 U. S. 452, 457, n. (1994), when
the issue is one of first impression and the Federal Gov-
ernment has staked out what appears to be a contrary
position. Thus, while I find this argument persuasive, I do
not base my analysis of this case on it and therefore con-
cur in the Court’s opinion.
