UNITED STATES
SECURITIES AND EXCHANGE COMMISSIONWashington, D.C. 20549

FORM 40-F

o

REGISTRATION STATEMENT PURSUANT TO SECTION 12 OF THE SECURITIES EXCHANGE ACT OF 1934ORý

ANNUAL REPORT PURSUANT TO SECTION 13(a) OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934


For the fiscal year ended December 31, 2012
Commission File Number 001-15150

ENERPLUS CORPORATION(Exact name of Registrant as specified in its charter)

Alberta, Canada(Province or other jurisdiction of
incorporation or organization)

1311(Primary Standard Industrial
Classification Code Number
(if applicable))

N/A(I.R.S. Employer Identification
Number (if applicable))


The Dome Tower, 3000, 333 - 7th Avenue S.W.
Calgary, Alberta, Canada T2P 2Z1
(403) 298-2200(Address and telephone number of Registrant's principal executive offices)

CT Corporation System
111 Eighth Avenue, 13th Floor
New York, New York 10011
(212) 894-8940(Name, address (including zip code) and telephone number (including area code)
of agent for service in the United States)

Securities
registered or to be registered pursuant to Section 12(b) of the Act:

Title of each class

Name of each exchange on which registeredCommon Shares

Toronto Stock Exchange
The New York Stock Exchange


Securities
registered or to be registered pursuant to Section 12(g) of the Act: None

Securities
for which there is a reporting obligation pursuant to Section 15(d) of the Act: None

For
annual reports, indicate by check mark the information filed with this Form:

ý    Annual
information form                                    ý Audited annual financial statements

Indicate the number of outstanding shares of each of the issuer's classes of capital or common stock as of the close of the period covered by the annual report.

198,684,166
Common Shares

Indicate
by check mark whether the Registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Exchange Act during the preceding 12 months (or for such
shorter period that the Registrant was required to file such reports) and (2) has been subject to such filing requirements for the past 90 days.

Yes    ý                                    No
    o

Indicate by check mark whether the Registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and
posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the Registrant was
required to submit and post such files).

Yes    o                                    No
    o





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FORWARD-LOOKING STATEMENTS

This Annual Report on Form 40-F contains or incorporates by reference forward-looking statements relating to future
events or future performance. In some cases, forward-looking statements can be identified by terminology such as "may", "should", "expects", "projects", "plans", "anticipates" and similar expressions.
These statements represent management's expectations or beliefs concerning, among other things, future operating results and various components thereof or the economic performance of the Registrant.
Undue reliance should not be placed on these forward-looking statements which are based upon management's assumptions and are subject to known and unknown risks and uncertainties which may cause
actual performance and financial results in future periods to differ materially from any projections of future performance or results expressed or implied by such forward-looking statements.
Accordingly, readers are cautioned that events or circumstances could cause results to differ materially from those predicted. For a description of some of these risks, uncertainties, events and
circumstances, readers should review the disclosure under the heading "Risk Factors" in the Registrant's Annual Information Form for the year ended December 31, 2012, which is attached as
Exhibit 99.1 to this Annual Report on Form 40-F and is incorporated by reference herein. Other than as required by applicable law, the Registrant undertakes no obligation to
update publicly or revise any forward-looking statements contained herein and such statements are expressly qualified by the cautionary statement.

ANNUAL INFORMATION FORM, AUDITED ANNUAL CONSOLIDATED
FINANCIAL STATEMENTS AND MANAGEMENT'S DISCUSSION AND ANALYSIS

A.    Annual Information Form

The Registrant's Annual Information Form for the year ended December 31, 2012 is attached as Exhibit 99.1 to this Annual Report on
Form 40-F and is incorporated by reference herein.

B.    Audited Annual Consolidated Financial Statements

The Registrant's audited annual consolidated financial statements for the year ended December 31, 2012, including the report of the independent registered
chartered accountants with respect thereto, are attached as Exhibit 99.2 to this Annual Report on Form 40-F and are incorporated by reference herein.

C.    Management's Discussion and Analysis

The Registrant's Management's Discussion and Analysis for the year ended December 31, 2012 is attached as Exhibit 99.3 to this Annual Report on
Form 40-F and is incorporated by reference herein.

DISCLOSURE REGARDING CONTROLS AND PROCEDURES

A.    Disclosure Controls and Procedures

As of the end of the Registrant's fiscal year ended December 31, 2012, an evaluation of the effectiveness of the Registrant's "disclosure controls and
procedures" (as such term is defined in Rules 13a-15(e) and 15d-15(e) of the Securities Exchange Act of 1934, as amended (the "Exchange Act")) was carried out by the
Registrant's principal executive officer and principal financial officer. Based upon that evaluation, the Registrant's principal executive officer and principal financial officer have concluded that
as of the end of that fiscal year, the Registrant's disclosure controls and procedures (which include, without limitation, controls and procedures designed to ensure that information required to be
disclosed by the Registrant in the reports that it files or submits under the Securities Exchange Act of 1934 is accumulated and communicated to the Registrant's management, including its principal
executive and principal financial officers, or persons performing similar functions, as appropriate to allow for timely decisions regarding required disclosure) are effective to ensure that the
information required to be disclosed by the Registrant in the reports
that it files or submits under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in Securities and Exchange Commission rules and forms.

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B.    Management's Annual Report on Internal Control Over Financial Reporting

The Registrant's report of management on the Registrant's internal control over financial reporting is included under the heading "Management's Report on Internal
Control Over Financial Reporting" contained in Exhibit 99.2 to this Annual Report on Form 40-F, which report of management is incorporated by reference herein.

C.    Attestation Report of the Registered Public Accounting Firm

The attestation report of the independent registered chartered accountants on the effectiveness of internal control over financial reporting is included under the
heading "Report of Independent Registered Chartered Accountants" contained in Exhibit 99.2 to this Annual Report on Form 40-F, which attestation report is incorporated by
reference herein.

D.    Changes in Internal Control over Financing Reporting

During the fiscal year ended December 31, 2012, there were no changes in the Registrant's internal control over financial reporting that have materially
affected, or are reasonably likely to materially affect, the Registrant's internal control over financial reporting.

NOTICES PURSUANT TO REGULATION BTR

None.

AUDIT COMMITTEE FINANCIAL EXPERT

The board of directors of the Registrant has determined that Mr. Robert B. Hodgins, a member and the chairman of the
Registrant's Audit & Risk Management Committee, is an "audit committee financial expert" (as such term is defined by the rules and regulations of the Securities and Exchange Commission) and is
"independent" (as that term is defined by the New York Stock Exchange's listing standards applicable to the Registrant).

The
Securities and Exchange Commission has indicated that the designation or identification of a person as an "audit committee financial expert" does not (i) mean that such person
is an "expert" for any purpose, including without limitation for purposes of Section 11 of the Securities Act of 1933, (ii) impose on such person any duties, obligations or liability
that are greater than the duties, obligations and liability imposed on such person as a member of the audit committee and the board of directors in the absence of such designation or identification,
or (iii) affect the duties, obligations or liability of any other member of the audit committee or the board of directors.

CODE OF ETHICS

The Registrant has adopted a "code of ethics" (as that term is defined by the rules and regulations of the Securities and Exchange
Commission), entitled the "Code of Business Conduct" (as amended to the date of this Form 40-F, the "Code of Business Conduct"), that applies to each director, officer (including
its principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions), employee and consultant of the Registrant. The
Registrant amended the Code of Business Conduct effective February 23, 2012 and January 31, 2013. The only amendment of a substantive nature was the addition of more comprehensive
anti-corruption practices. During the fiscal year ended December 31, 2012, there were no waivers, including implicit waivers, granted from any provision of the Code of Business
Conduct that applied to the Registrant's principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions.

The
Code of Business Conduct is attached as Exhibit 99.11 to this Annual Report on Form 40-F and is incorporated by reference herein.

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PRINCIPAL ACCOUNTANT FEES AND SERVICES AND
PRE-APPROVAL POLICIES AND PROCEDURES

The aggregate fees paid by the Registrant to Deloitte LLP, Independent Registered Chartered Accountants, the Registrant's
principal accountant, for professional services rendered in the Registrant's last two fiscal years are as follows:

2012

2011(in Cdn$
thousands)Audit fees(1)


809.9


855.8Audit-related fees(2)





Tax fees(3)


678.9


504.7All other fees(4)





Total


1,488.8


1,360.5


(1)Audit
fees were for professional services rendered by Deloitte LLP for the audit of the Registrant's annual financial statements and reviews of the
Registrant's quarterly financial statements, as well as services provided in connection with statutory and regulatory filings or engagements.(2)Audit-related
fees are fees for assurance and related services reasonably related to the performance of the audit or review of the Registrant's financial
statements and not reported under "Audit Fees" above.(3)Tax
fees were for tax compliance, tax advice and tax planning.(4)All
other fees are fees for products and services provided by Deloitte LLP other than those described as "Audit fees", "Audit-related fees" and "Tax
fees".


The
Registrant's Audit & Risk Management Committee has implemented a policy restricting the services that may be provided by the Registrant's auditors and the fees paid to the
Registrant's auditors. Prior to the engagement of the Registrant's auditors to perform both audit and non-audit services, the Audit & Risk Management Committee
pre-approves the provision of the services. In making their determination regarding non-audit services, the Audit & Risk Management Committee considers the compliance
with the policy and the provision of non-audit services in the context of avoiding an adverse impact on auditor independence. All audit and non-audit fees paid to
Deloitte LLP in 2011 and 2012 were pre-approved by the Registrant's Audit & Risk Management Committee and none were approved on the basis of the de minimis exemption set
forth in Rule 2-01(c)(7)(i)(C) of Regulation S-X. Based on the Audit & Risk Management Committee's discussions with management and the independent
auditors, the committee is of the view that the provision of the non-audit services by Deloitte LLP described above is compatible with maintaining that firm's independence from the
Registrant.

OFF-BALANCE SHEET ARRANGEMENTS

The Registrant has no off-balance sheet arrangements that have or are reasonably likely to have a current or future effect
on the Registrant's financial condition, changes in financial condition, revenues or expenses, results of operations, liquidity, capital expenditures or capital resources that is material to
investors.

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TABULAR DISCLOSURE OF CONTRACTUAL OBLIGATIONS

The following table sets forth the Registrant's known contractual obligations as of December 31, 2012:

Payments due by period
(in Cdn$ millions)Contractual Obligations(1)

Total

2013

2014 to 2015

2016 to 2017

2018 +Bank credit facility

$
261.0

$


$
261.0

$


$
Senior unsecured notes(2)


808.6


45.6


136.1


115.4


511.5Transportation commitments


126.5


49.5


42.5


21.2


13.3Processing commitments


1.2


0.4


0.6


0.2


Drilling and completions commitment


25.5


20.1


5.4





Decommissionary liability(3)


659.7


25.8


52.0


52.0


529.9Office leases


81.8


13.3


23.8


22.8


21.9Total commitments(4)

$
1,964.3

$
154.7

$
521.4

$
211.6

$
1,076.6


Notes: (1)U.S.
dollar commitments have been converted to Canadian dollars using the December 31, 2012 foreign exchange rate of Cdn$1.00 = US$1.0051.(2)Interest
payments have not been included.(3)Based
on the Registrant's current spending estimates.(4)Crown
and surface royalties, lease rentals and mineral taxes (hydrocarbon production rights) have not been included as amounts paid depend on future
ownership, production, prices and the legislative environment.


Additional
disclosure regarding the Registrant's contractual obligations as of December 31, 2012 is provided under the heading "Liquidity and Capital
ResourcesCommitments" in the Registrant's Management's Discussion and Analysis for the year ended December 31, 2012 attached as Exhibit 99.3 to this Annual Report on
Form 40-F, which disclosure is incorporated by reference herein, and in Note 17 to the Registrant's audited annual consolidated financial statements for the year ended
December 31, 2012 attached as Exhibit 99.2 to this Annual Report on Form 40-F, which note is incorporated by reference herein.

IDENTIFICATION OF THE AUDIT COMMITTEE

The Registrant has a separately-designated standing audit committee established in accordance with section 3(a)(58)(A) of the
Exchange Act. The members of the Registrant's Audit & Risk Management Committee are Robert B. Hodgins (as Chairman), Elliott Pew, Glen D. Roane and Sheldon B. Steeves. Douglas R. Martin, the
chairman of the board of directors of the Registrant, is anex officiomember of the Audit & Risk Management Committee.

COMPLIANCE WITH NYSE CORPORATE GOVERNANCE RULES

The Registrant has reviewed the New York Stock Exchange's corporate governance rules and confirms that the Registrant's corporate
governance practices are not significantly nor materially different than those required of domestic companies under the New York Stock Exchange's listing standards except that, as a foreign private
issuer, the Registrant is not obligated to, and does not have, an internal audit function.

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UNDERTAKING AND CONSENT TO SERVICE OF PROCESS

A.    Undertaking

The Registrant undertakes to make available, in person or by telephone, representatives to respond to inquiries made by the Commission staff, and to furnish
promptly, when requested to do so by the Commission staff, information relating to: the securities registered pursuant to Form 40-F; the securities in relation to which the
obligation to file an annual report on Form 40-F arises; or transactions in said securities.

B.    Consent to Service of Process

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SIGNATURES

Pursuant to the requirements of the Exchange Act, the Registrant certifies that it meets all of the requirements for filing on
Form 40-F and has duly caused this annual report to be signed on its behalf by the undersigned, thereto duly authorized.

ENERPLUS CORPORATIONBy:

/s/ GORDON J. KERR Gordon J. Kerr
President and Chief Executive OfficerDate: February 22, 2013


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EXHIBIT INDEX

99.1

Annual Information Form for the year ended December 31, 2012 dated February 22, 2013.99.2

Audited annual consolidated financial statements for the year ended December 31, 2012.99.3

Management's Discussion and Analysis for the year ended December 31, 2012.99.4

Consent of Independent Registered Chartered Accountants.99.5

Consent of McDaniel & Associates Consultants Ltd.99.6

Consent of Haas Petroleum Engineering Services, Inc.99.7

Certification of the Chief Executive Officer pursuant to Rule 13a-14(a) or Rule 15d-14(a) of the Securities Exchange Act of 1934.99.8

Certification of the Chief Financial Officer pursuant to Rule 13a-14(a) or Rule 15d-14(a) of the Securities Exchange Act of 1934.99.9

Certification of the Chief Executive Officer pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.99.10

Certification of the Chief Financial Officer pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.99.11

Code of Business Conduct dated January 31, 2013.


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