FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

AMANDA ARMSTRONG; HUI MIN             
ZHAO; XIU ZHEN QI; MEI LIAN
CHEN; EDWARD LIEBERMAN; JOHN
DOES,                                       No. 07-16126
             Plaintiffs-Appellants,
               v.                            D.C. No.
                                          CV-07-00002-ARM
COMMONWEALTH OF THE NORTHERN                  OPINION
MARIANA ISLANDS; DEPARTMENT OF
FINANCE,
            Defendants-Appellees.
                                      
       Appeal from the United States District Court
      for the District of the Northern Mariana Islands
         Alex R. Munson, District Judge, Presiding

                Argued and Submitted
          November 18, 2008—Honolulu, Hawaii

                   Filed August 7, 2009

     Before: Mary M. Schroeder, Richard A. Paez, and
             N. Randy Smith, Circuit Judges.

                  Opinion by Judge Paez




                           10647
                   ARMSTRONG v CNMI                 10649


                       COUNSEL

Alexis Ann Fallon, Fallon Law Offices, Saipan, MP, for the
plaintiffs-appellants.
10650                    ARMSTRONG v CNMI
Gregory Baka, Deputy Attorney General, Office of the Attor-
ney General, Saipan, MP, for the defendant-appellee.


                              OPINION

PAEZ, Circuit Judge:

   Amanda Armstrong and twenty-eight taxpayers (hereinafter
referred to collectively as “Armstrong”) appeal from the dis-
trict court’s order dismissing their action against the Com-
monwealth of the Northern Mariana Islands (“CNMI”)
seeking recovery of income tax rebates and accrued interest
under the CNMI tax code. Armstrong also seeks declaratory
and injunctive relief regarding the manner in which the CNMI
government administers the payment of rebates. The district
court concluded that it lacked subject matter jurisdiction over
the claims, and dismissed the action pursuant to Federal Rule
of Civil Procedure 12(b)(1).

   Armstrong contends first that the district court had federal
question jurisdiction over the claims under 28 U.S.C. § 1331
because the CNMI has adopted the Internal Revenue Code, 26
U.S.C. § 1 et seq. (“IRC”), as a local territorial income tax
called the Northern Mariana Territorial Income Tax
(“NMTIT”). Armstrong argues that because the provisions of
the NMTIT “mirror” those of the IRC, claims that arise under
the NMTIT raise a federal question and therefore “arise
under” the laws of the United States for the purposes of
§ 1331.

   Armstrong also argues that the district court had original
jurisdiction over her claims pursuant to a provision in the
Covenant to Establish a Commonwealth of the Northern Mar-
iana Islands in Political Union with the United States of
America (“Covenant”), reprinted in 48 U.S.C. § 1801 (note),1
  1
    In her reply brief, Armstrong also argued that because the tax rebate
claims “arise out of and directly concern the scope and effect” of the Cov-
                        ARMSTRONG v CNMI                         10651
which provides that the United States tax laws shall be
adopted by the CNMI as a local territorial income tax and
shall be in force in the same manner as those laws are in force
in Guam. Thus, argues Armstrong, just as the Guam district
court has jurisdiction over tax-related matters that arise under
the provisions of Guam’s tax code, which also mirrors United
States tax laws, the CNMI district court has jurisdiction over
tax-related matters that arise under the provisions of the
CNMI’s tax code.

   We have jurisdiction under 28 U.S.C. § 1291 and 48 U.S.C.
§ 1821(a). Because we agree with the district court’s determi-
nation that it lacked subject matter jurisdiction over Arm-
strong’s claims, we affirm.

                                   I.

                            BACKGROUND

  A. The CNMI Covenant and adoption of federal tax law
  as a local territorial tax system

   From 1947 until 1986, what is now the CNMI was a trust
territory administered by the United States pursuant to an
agreement with the Security Council of the United Nations.
See generally Joseph E. Horey, The Right of Self-Government
in the Commonwealth of the Northern Mariana Islands, 4
Asian-Pac. Law & Policy Journal 180, 181 (2003) (providing
brief overview of CNMI history); see also 48 U.S.C. § 1801

enant, the district court had jurisdiction pursuant to Covenant § 903,
reprinted in 48 U.S.C. § 1801 (note), which provides that “[n]othing
herein shall prevent the presentation of cases or controversies arising
under this Covenant to courts established by the Constitution or laws of
the United States.” At oral argument, however, Armstrong withdrew this
additional argument. We therefore need not address either its merits or
whether, as the CNMI contends, Armstrong waived the argument by not
raising it in the district court or in her opening brief.
10652                    ARMSTRONG v CNMI
(quoting language of Pub. L. 94-241, describing trusteeship
terms); United States v. De Leon Guerrero, 

, 751
(9th Cir. 1993). In 1972, the Islands entered into formal nego-
tiations with the United States to finalize and make permanent
the relationship between the entities. See 

15, 1975, the negotiations culminated with the
signing of the Covenant.2 See De Leon 

; see also Horey, 4 Asian-Pac. Law & Policy Journal at
181-85 (describing history of Covenant and several Covenant
provisions). This instrument, which governs the CNMI’s
political relationship with the United States, provides that the
United States District Court for the Northern Mariana Islands
(“NMI district court”), as a court established under Article IV
of the United States Constitution, shall have the same jurisdic-
tion as other United States District Courts. See Covenant
§ 402(a), codified as amended at 48 U.S.C. § 1822; see also
Nguyen v. United States, 

, 72-73 (2003) (describ-
ing how jurisdiction is vested in Article IV courts by acts of
Congress).

   The Covenant also contains provisions that govern the
adoption of an income tax system for the CNMI. First, Cove-
nant section 601 provides that “[t]he income tax laws in force
in the United States will come into force in the Northern Mar-
iana Islands as a local territorial income tax on the first day
of January following the effective date of this Section, in the
same manner as those laws are in force in Guam.” To imple-
ment this provision, the CNMI legislature adopted the
NMTIT, enacting the Northern Marianas Income Tax Act of
1982 and 1984, currently codified as amended in the Northern
Mariana Islands Commonwealth Code (“CMC”) at 4 CMC
§§ 1701-17 (2004). See N. Mar. I. Pub. L. 3-11 (May 27,
  2
    In 1986, with the Covenant fully in effect, the United States—by Presi-
dential Proclamation—terminated the Trusteeship Agreement with respect
to the CNMI. See De Leon 

.
                       ARMSTRONG v CNMI                     10653
1982), N. Mar. I. Pub. L. 4-24 (Dec. 11, 1984), N. Mar. I.
Pub. L. 9-22, § 6 (Jan. 24, 1995).

  Under the NMTIT, CNMI taxpayers

    are not required to pay federal income taxes to the
    United States Internal Revenue Service. However,
    over the course of a tax year, a CNMI taxpayer pays
    the exact same amount of tax to the CNMI govern-
    ment, through either payroll withholding deductions
    or quarterly payments, as a citizen of one of the sev-
    eral States with the same income would pay to the
    United States government.

Olopai v. Guerrero, No. 93-0002, 

, at *1 (D.
N. Mar. I. Sept. 24, 1993); see 4 CMC § 1802 (describing a
General Fund “into which all revenues raised pursuant to the
tax laws and other revenue laws . . . shall be deposited . . . .”).

   Section 601’s provision that the CNMI shall adopt the
United States tax laws as a local territorial income tax consti-
tutes what is commonly referred to as a “mirror code” system.
Congress has described such systems, which are implemented
in several insular areas, including Guam, the Virgin Islands,
and Puerto Rico, as “the provisions of law . . . which make
the provisions of the income tax laws of the United States . . .
in effect in a possession of the United States.” 26 U.S.C.
§ 931 (note); see 48 U.S.C. § 1421i (Guam); 48 U.S.C. § 1397
(Virgin Islands); 48 U.S.C. § 734 (Puerto Rico).

   In addition to Covenant section 601, Covenant section 602
authorizes the CNMI to enact additional local tax laws: “The
Government of the Northern Mariana Islands may by local
law impose such taxes, in addition to those imposed under
section 601, as it deems appropriate and provide for the rebate
of any taxes received by it . . . .” 48 U.S.C. § 1801 (note).
Accordingly, several provisions of the NMTIT impose addi-
tional tax obligations on the CNMI and its taxpayers, and set
10654                    ARMSTRONG v CNMI
forth a procedure by which CNMI taxpayers may obtain sig-
nificant rebates on taxes owed. See 4 CMC § 1708 (establish-
ing rebate amounts); 4 CMC § 1711(b) (establishing rebate
procedures); 4 CMC § 1713 (specifying that the interest on
overpayments shall be calculated only on the amount not
already rebated); 4 CMC § 1714 (discussing special rebate
trust account); 4 CMC § 1810(b) (discussing authority to
make refunds).

  B.    Armstrong’s Claims

   On January 19, 2007, Armstrong filed a complaint in the
NMI district court.3 She alleged, on behalf of herself and all
others similarly situated, that the CNMI failed to calculate and
pay statutory interest due on accrued rebate claims in viola-
tion of the NMTIT. Armstrong sought a judicial declaration
that (1) interest applies to late-paid CNMI rebates; (2) the
CNMI government is required to pay such interest; (3) CNMI
taxpayers are entitled to offset their accrued rebates, plus
interest, as a credit against taxes owed on wages; and (4) the
CNMI government is estopped from asserting the applicable
statute of limitations contained in 26 U.S.C. § 6511, due to
the CNMI government’s inaccurate representations that
CNMI taxpayers were not entitled to interest on late-paid
rebates.

   Armstrong also sought injunctive relief enjoining the
CNMI government from expending funds set aside in the Spe-
cial Rebate Trust Account, as required by 4 CMC § 1714, so
that the outstanding and accrued rebate claims could be satis-
fied. Last, Armstrong sought payment of accrued interest, in
amounts to be proven at trial.
  3
   Because the district court dismissed Armstrong’s action under Federal
Rule of Civil Procedure 12(b)(1) without making any factual findings, we
take the allegations in the complaint as true. Ojo v. Farmers Group, Inc.,

, 1183 (9th Cir. 2009) (quoting Carson Harbor Village Ltd.
v. City of Carson, 

, 826 (9th Cir. 2004)).
                         ARMSTRONG v CNMI                          10655
  C.    The District Court’s Ruling

   In response to Armstrong’s complaint, the CNMI moved to
dismiss under Federal Rule of Civil Procedure 12(b)(1) on the
ground that the district court lacked subject matter jurisdic-
tion. The district court granted the CNMI’s motion. Although
the court recognized that the CNMI adopted the United States
tax laws as required by the Covenant, it reasoned that those
laws came into force as local territorial taxes, and that there-
fore no provision in the Covenant—and no other authority—
authorized the court to exercise jurisdiction over claims seek-
ing enforcement of these local laws. Armstrong timely
appealed.

                                   II.

                               ANALYSIS

  Armstrong presents two arguments that the district court
had subject matter jurisdiction over her claim.4 We address,
and reject, each in turn.

   First, Armstrong contends that the claims invoke federal
question jurisdiction under 28 U.S.C. § 1331. Because the
rebate provisions of the NMTIT provide the legal basis for
Armstrong’s rebate claims, however, we conclude that the
claims do not arise under federal law for the purposes of fed-
eral question jurisdiction.

   Second, Armstrong argues that the court had original juris-
diction over the claims under Covenant section 601, which
provides that the United States tax laws shall be in force in the
CNMI in the same manner as they are in force in Guam.
  4
   We review de novo the district court’s decision to dismiss a complaint
under Federal Rule of Civil Procedure 12(b)(1). Stratman v. Leisnoi, Inc.,

, 1167 (9th Cir. 2008); Wah Chang v. Duke Energy Trading
& Mktg., LLC, 

, 1225 (9th Cir. 2007).
10656                 ARMSTRONG v CNMI
Although in Guam, the district court has exclusive jurisdiction
over tax-related claims, the instrument that governs Guam’s
relationship with the United States—and that confers exclu-
sive jurisdiction over tax matters to the United States District
Court for Guam—is entirely different from the Covenant that
governs the CNMI’s relationship with the United States. See
48 U.S.C. § 1421i. We see no reason to interpret section 601’s
reference to Guam to incorporate a jurisdictional provision
that is (1) specific to the United States’s relationship with
Guam and (2) not contained in either the Covenant or the
IRC.

  A.    Federal Question Jurisdiction

   Armstrong contends that because the provisions of the
NMTIT “mirror” the provisions of the IRC, the claims she
brought under the NMTIT necessarily implicate questions of
federal law and are therefore subject to federal question juris-
diction under 28 U.S.C. § 1331. We disagree.

   [1] Section 1331 provides that “[t]he district courts shall
have original jurisdiction of all civil actions arising under the
Constitution, laws, or treaties of the United States.” As noted
above, section 402(a) of the Covenant affirms that the United
States District Court for the Northern Mariana Islands shares
the same jurisdiction as a district court of the United States.
Thus, if Armstrong’s claims “aris[e] under the Constitution,
laws, or treaties of the United States,” the NMI district court
would have federal question jurisdiction and could address the
merits of her claims.

   “The Court has consistently interpreted jurisdictional stat-
utes with an ‘arising under’ qualification,” including § 1331,
“as ‘giv[ing] the lower federal courts jurisdiction to hear,
originally or by removal from a state court, only those cases
in which a well-pleaded complaint establishes either that [1]
federal law creates the cause of action or that [2] the plain-
tiff ’s right to relief necessarily depends on resolution of a
                           ARMSTRONG v CNMI                            10657
substantial question of federal law.’ ” Williston Basin Inter-
state Pipeline Co. v. An Exclusive Gas Storage Leasehold and
Easement in the Cloverly Subterranean Geological Forma-
tion, 

, 1100 (9th Cir. 2008) (quoting Franchise
Tax. Bd. v. Constr. Laborers Vacation Trust, 

, 27-
28 (1983)). Where, as here, plaintiffs invoke the second basis
for jurisdiction—arguing not that federal law itself creates the
cause of action, but instead that their right to relief necessarily
depends on resolution of a substantial question of federal law
—we must examine whether such question is a necessary ele-
ment of one of their well-pleaded state (or, in this case, Com-
monwealth) claims. See Wander v. Kaus, 

, 858
(9th Cir. 2002) (quoting Franchise Tax. 

(1983)). Because the NMTIT provisions mirror the IRC pro-
visions, Armstrong argues that her claims “arise under” the
IRC and therefore raise a disputed and substantial federal
issue. See Williston 

(quoting Grable
& Sons Metal Prods., Inc. v. Darue Eng’g & Mfg., 

, 314 (2005)).

   [2] Here, Armstrong’s contention essentially amounts to an
argument that because the IRC serves as the basis for the
CNMI tax code, actions that arise under the NMTIT raise fed-
eral questions. Armstrong, however, presents us with no
authority for her argument that under a mirror code system,
it is federal law, not local law, that is in force, or that claims
arising under such a system necessarily raise federal questions.5
   5
     That the District Court of Guam has original, exclusive jurisdiction
over tax-related matters arising under the Guam “mirror code,” see 48
U.S.C. § 1421i(h)(1), does not further Armstrong’s § 1331 jurisdictional
argument, and the fact that at one time the District Court of the United
States Virgin Islands had jurisdiction over certain tax-related matters aris-
ing under the Virgin Islands’s “mirror code,” see 

. Code Ann. tit.
33 § 1692; 48 U.S.C. § 1612, does not aid Armstrong either. See Edwards
v. Hovensa, LLC, 

(3d Cir. 2007) (explaining that the Virgin
Islands’s legislature withdrew such jurisdiction when it transferred juris-
diction to its local superior court). In providing for district court jurisdic-
tion over tax-related matters in Guam and the Virgin Islands, Congress
10658                     ARMSTRONG v CNMI
The Covenant’s mandate that the CNMI adopt the provisions
of the IRC as local territorial laws—which raise revenue for
the CNMI government, see Olopai, 

, at *1—
disaffirms Armstrong’s argument that Congress intended that
all claims brought under the NMTIT would invoke federal
question jurisdiction under § 1331. The language of the Cove-
nant suggests that the opposite is true.6

   [3] More importantly, as the district court pointed out,
Armstrong’s claims primarily involved the additional local
provisions of the NMTIT, not the NMTIT provisions that
were modeled after the IRC. In other words, Armstrong
sought enforcement of local territorial income tax laws
enacted pursuant to Covenant section 602. These local tax law
claims do not possess, as necessary elements, “substantial,
disputed” questions of federal law. See 

(quoting Franchise Tax. 

(1983)).

   [4] In sum, we conclude that because the NMTIT is a local,

enacted specific provisions tailored to the United States’s relationship with
these entities. Contrary to Armstrong’s suggestion, these provisions are
unrelated to the Covenant, which governs the relationship between the
United States and the CNMI. Indeed, the unique jurisdictional provisions
in the instruments governing the United States’s relationship with other
territories underscores the CNMI’s argument that whether a federal district
court has jurisdiction over tax-related matters does not turn on whether the
territorial government adheres to a “mirror code.”
    6
      We do not foreclose the possibility that there might be some claim
under the NMTIT of such a nature that its adjudication would involve a
substantial question of federal law that might give rise to jurisdiction
under § 1331. See 

-59 (“[C]ourts should approach
the issue of federal question jurisdiction as one requiring sensitive judg-
ments about congressional intent, judicial power, and the federal question.
. . . Accordingly, when determining the propriety of federal question juris-
diction, courts look both to congressional intent and the nature of the fed-
eral interest at stake.”) (internal quotation marks and citation omitted). See
also Grable & 

; Merrell Dow Pharms., Inc. v.
Thompson, 

, 810 (1986).
                          ARMSTRONG v CNMI                           10659
territorial income tax code, and because Armstrong’s NMTIT
claims seek to enforce the additional rebate provisions
enacted pursuant to Covenant section 602, Armstrong’s
NMTIT claims were not subject to federal question jurisdic-
tion under 28 U.S.C. § 1331.7

  B.    Original Jurisdiction under Covenant Section 601

   Armstrong also argues that the district court had original
jurisdiction over her action under Covenant section 601(a),
which, as noted above, provides that the income tax laws in
force in the United States will be enforced “in the same man-
ner as those laws are in force in Guam” (emphasis added).
Because tax-related disputes under Guam’s income tax laws
are subject to jurisdiction in the district court, Armstrong con-
tends that the NMI district court has jurisdiction over disputes
related to the NMTIT. Again, we disagree.

   [5] First, the Guam district court has jurisdiction over tax-
related matters pursuant to a provision of the Guam Organic
Act; no such provision is contained in the IRC, the NMTIT,
or the Covenant. Specifically, 48 U.S.C. § 1421i(h)(1) pro-
vides, in pertinent part, that “the District Court of Guam shall
   7
     Armstrong briefly argues that section 1271 of the Tax Reform Act of
1986, Pub. L. 99-514, 100 Stat. 2085, which authorizes insular areas such
as Guam and the CNMI to “de-link” from the mirror code income tax sys-
tem under certain conditions, further demonstrates the existence of federal
jurisdiction. Although Armstrong’s argument is not entirely clear, we con-
strue it as support for her § 1331 jurisdictional argument. According to
Armstrong, by providing for de-linkage in section 1971, Congress implic-
itly recognized that the federal income tax laws are in force in the CNMI
as federal law, not local law. This argument, however, disregards the man-
date of Covenant section 601 as explained both above and infra at 10660,
and misinterprets Congress’ authorization for insular areas such as the
CNMI and Guam to adopt a simplified income tax code that is tailored to
the unique circumstances of each area. Further, section 1271 does not
address the NMI district court’s jurisdiction over tax-related claims arising
under the NMTIT. In light of the text and purpose of section 1271, it does
not support Armstrong’s § 1331 jurisdictional argument.
10660                  ARMSTRONG v CNMI
have exclusive original jurisdiction over all judicial proceed-
ings in Guam . . . with respect to the Guam Territorial income
tax.” (emphasis added). See Gov’t of Guam v. Sup. Ct. of
Guam, 

, 755 (9th Cir. 1993) (affirming that 48
U.S.C. § 1421i(h) requires that all matters “involving” the ter-
ritorial income tax must be litigated in the district court).

   [6] No similar provision exists in the Covenant; in fact, the
Northern Marianas Tax Act of 1984, as amended, explicitly
contemplates that the local superior court shall have jurisdic-
tion over tax matters, stating that “[i]n applying the NMTIT
for any purpose . . . the . . . provisions of the IRC shall be read
so as to substitute ‘Commonwealth of the Northern Mariana
Islands’ for ‘United States’ . . . and . . . ‘Superior Court of the
Northern Mariana Islands’ for ‘district court’ . . . .” 4 CMC
§ 1701(e). The legislative history of Guam’s Organic Act,
moreover, reflects that section 1421i(h) was added in
response to a unique problem Guam faced regarding uniform
adjudication of refund claims pending in Guam’s local court.
See S. Rep. No. 85-2176 (1958), as reprinted in 1958
U.S.C.C.A.N. 3647, 3653-54.

   Second, as discussed above, Covenant section 601, which
directs the CNMI to adopt the federal tax laws, specifies that
the applicable IRC provisions shall be enforced as local terri-
torial laws. In contrast, 48 U.S.C. § 1421i provides that “[t]he
income-tax laws in force in the United States of America and
those which may hereafter be enacted shall be held to be like-
wise in force in Guam . . . .” Use of the word “local” high-
lights the distinction between the CNMI’s mirror code tax
system and Guam’s.

   [7] Last, the CNMI’s enactment of the Northern Mariana
Island Income Tax Act of 1982 and 1984, noted above, is best
understood as reflecting the CNMI’s intent to ensure that
local tax disputes are adjudicated in the CNMI superior court.
The Act’s mandate that “superior court” shall be substituted
for “district court” highlights the CNMI’s intent to vest juris-
                      ARMSTRONG v CNMI                     10661
diction in the superior court, consistent with section 402 of
the Covenant as amended. See 48 U.S.C. § 1822 (“The Dis-
trict Court for the Northern Mariana Islands shall have origi-
nal jurisdiction in all causes in the Northern Mariana
Islands[,] . . . jurisdiction over which is not vested by the Con-
stitution or laws of the Northern Mariana Islands in a court or
courts of the Northern Mariana Islands.”) (emphasis added).

   [8] In sum, we are unpersuaded by Armstrong’s argument
that the Covenant incorporates § 1421i(h)’s grant of exclusive
jurisdiction over tax matters to the United States District
Court for Guam. The legislative history of § 1421i(h), the text
of the Covenant, and the enactment of the Northern Mariana’s
Income Tax Act all suggest otherwise. We therefore conclude
that the district court lacked original jurisdiction over Arm-
strong’s NMTIT claims and properly dismissed her action.

  AFFIRMED.