EXHIBIT 99.7



                           IMPORTANT TAX INFORMATION



   This tax information is provided in connection with the Harken Energy
Corporation (the "Company") prospectus dated           , 2003 (the
"Prospectus").



   Under the United States federal income tax laws, dividend payments that may
be made by the Company on shares of its Common Stock, par value $0.01, issued
upon the exercise of non-transferable subscription rights (the "Rights") may be
subject to backup withholding. Generally such payments will be subject to
backup withholding unless the holder (i) is exempt from backup withholding or
(ii) furnishes the payer with its correct taxpayer identification number (TIN)
and certifies that the number provided is correct and further certifies that
such holder is not subject to backup withholding as a result of a failure to
report all interest or dividend income. Each Rights holder that exercises
Rights and wants to avoid backup withholding should provide the Subscription
Agent, as the Company's agent in respect of exercised Rights (the "Requester"),
with such holder's correct taxpayer identification number (or with a
certification that such holder is awaiting a taxpayer identification number)
and with a certification that such holder is not subject to backup withholding
by completing Substitute Form W-9 below.


   Certain holders (including, among others, all corporations and certain
foreign individuals) are exempt from these backup withholding and reporting
requirements. In general, in order for a foreign individual to qualify as an
exempt recipient, that holder must submit a statement, signed under the
penalties of perjury, attesting to that individual's exempt status. Such
statements may be obtained from the Subscription Agent. Exempt holders, while
not required to file Substitute Form W-9, should file Substitute Form W-9 to
avoid possible erroneous backup withholding. See the enclosed Guidelines for
Request for Taxpayer Identification Number and Certification on Substitute Form
W-9 for additional instructions.

   If backup withholding applies, the Company or the Subscription Agent, as the
case may be, will be required to withhold up to 30% of any such dividend
payments made to a Rights holder that exercises Rights. Backup withholding is
not an additional tax. Rather, the amount of backup withholding is treated,
like any other withheld amounts, as an advance payment of the person's tax
liability, and the tax liability of persons subject to backup withholding will
be reduced by the amount of tax withheld. If withholding results in an
overpayment of taxes, a refund may be obtained.

Purpose of Substitute Form W-9


   To prevent backup withholding on dividend payments, a Rights holder that
exercises Rights is required to notify the Subscription Agent of such holder's
correct taxpayer identification number by completing Substitute Form W-9 below
and certifying on Substitute Form W-9 that the taxpayer identification number
provided is correct (or that such Rights holder is awaiting a taxpayer
identification number). In addition, the holder is required to certify on
Substitute Form W-9 that it is (i) exempt from backup withholding, or (ii) not
subject to backup withholding due to prior under reporting of interest or
dividend income, or (iii) the Internal Revenue Service (the "IRS") has notified
it that it is no longer subject to backup withholding. Further, the holder must
also certify that it is a U.S. person.


What Number to Give the Subscription Agent

   The Rights holder that exercises Rights is required to give the Subscription
Agent the taxpayer identification number of the record owner of the shares of
Common Stock issued upon the exercise of the Rights. If such record owner is an
individual, the taxpayer identification number is the taxpayer's social
security number. For most other entities, the taxpayer identification number is
the employer identification number. If the shares of Common Stock issued upon
the exercise of the Rights are in more than one name or are not in the name of
the actual owner, consult the enclosed Guidelines for Request for Taxpayer
Identification Number and Certification on Substitute Form W-9 for additional
guidelines on what number to report. If the Subscription Agent is not provided
with the correct taxpayer identification number in connection with such
payments, the holder may be subject to a penalty imposed by the IRS.


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- -------------------------------------------------------------------------------------------------------------------

                    Requestor's Name:
                    Give form to the Requestor. DO NOT send to the IRS.
- -------------------------------------------------------------------------------------------------------------------

SUBSTITUTE                        -----------------------------------------------------------
Form W-9                          Name
                                  -----------------------------------------------------------
Department of the Treasury        Business name, if different from above
Internal Revenue Service          Check appropriate box:
                                  [_]  Individual/Sole Proprietor   [_]  Corporation  [_]  Partnership
                                  [_]  Other.......................................................................
                                  -----------------------------------------------------------
                                  Address (number, street, and apt. or suite no.)
                                  -----------------------------------------------------------
                                  City, State and Zip Code
                                  ---------------------------------------------------------------------------------

                                  PART I--Taxpayer Identification             Social Security Number:
                                  Number (TIN) Enter your TIN in the          ---------------------
                                  appropriate box. For most
                                  individuals, this is your social            Employer Identification Number:
                                  security number (SSN). For most             ---------------------
                                  other entities, it is your employer
                                  identification number (EIN).
                                  ---------------------------------------------------------------------------------

                                  PART II--If you do not have a TIN check the "TIN Applied for" box
                                  below. See "How to Get a TIN" in the enclosed guidelines. If you
                                  are exempt from backup withholding, check the "Exempt" box below.
                                  See "Exemption from Backup Withholding" in the enclosed guidelines.
                                  TIN Applied for [_]               Exempt [_]
- -------------------------------------------------------------------------------------------------------------------

                                  Part III--Certification
                                  Under penalties of perjury, I certify that:
                                  (1) The number shown on this form is my correct taxpayer
                                  identification number (or I am waiting for a number to be issued to
                                  me), and
                                  (2) I am not subject to backup withholding because: (a) I am exempt
                                  from backup withholding; or (b) I have not been notified by the
                                  Internal Revenue Service (IRS) that I am subject to backup
                                  withholding as a result of a failure to report all interest or
                                  dividends; or (c) the IRS has notified me that I am no longer
                                  subject to backup withholding.
                                  (3) I am a U.S. person (including a U.S. resident alien).
                                  Certification Instructions--You must cross out item (2) above if
                                  you have been notified by the IRS that you are subject to backup
                                  withholding because you have failed to report all interest and
                                  dividends on your tax return. However, if after being notified by
                                  the IRS that you were subject to backup withholding you received
                                  another notification from the IRS that you are no longer subject to
                                  backup withholding, do not cross out item (2). The Internal Revenue
                                  Service does not require your consent to any provision of this
                                  document other than the certifications required to avoid backup
                                  withholding.
                                  -----------------------------------------------------------
                                  Signature _________________________  Date __________________________
- -------------------------------------------------------------------------------------------------------------------



NOTE: Failure to complete this form may result in backup withholding of up to
30% on any payments made to you. Please review enclosed guidelines for request
for taxpayer identification number and certification on Substitute Form W-9 for
additional details.


Certificate of Awaiting Taxpayer Identification Number

   I certify under penalties of perjury that a taxpayer identification number
has not been issued to me, and either (a) I have mailed or delivered an
application to receive a taxpayer identification number to the appropriate
Internal Revenue Service Center or Social Security Administration Office or (b)
I intend to mail or deliver an application in the near future. I understand
that if I do not provide a taxpayer identification number to the requester a
portion (not to exceed 30%) of all reportable payments made to me will be
retained and may be remitted to the Internal Revenue Service as backup
withholding until I provide a taxpayer identification number to the requester.

Signature _______________________________  Date ________________________________
- --------------------------------------------------------------------------------
                              Name (Please Print)

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              GUIDELINES FOR REQUEST FOR TAXPAYER IDENTIFICATION
                NUMBER AND CERTIFICATION ON SUBSTITUTE FORM W-9

What Name and Number to Give the Requester

   Name.  If you are an individual, you must generally enter the name shown on
your Social Security card. However, if you have changed your last name, for
instance, due to marriage, without informing the Social Security Administration
of the name change, enter your first name, the last name shown on your Social
Security card, and your new last name. If the account is in joint names, list
first and then circle the name of the person or entity whose number you enter
in Part I of the form.

   Sole Proprietor--You must enter your individual name as shown on your Social
Security card. You may enter your business, trade or "doing business as" name
on the business name line.

   Other Entities--Enter the business name as shown on required federal income
tax documents. This name should match the name shown on the charter or other
legal document creating the entity. You may enter any business, trade or "doing
business as" name on the business name line.

   Taxpayer Identification Number (TIN).  You must enter your taxpayer
identification number in the appropriate box. If you are a resident alien and
you do not have and are not eligible to get a Social Security number, your
taxpayer identification number is your IRS individual taxpayer identification
number (ITIN). Enter it in the Social Security number box. If you do not have
an individual taxpayer identification number, see "How to Get a TIN" below. If
you are a sole proprietor and you have an employer identification number, you
may enter either your Social Security number or employer identification number.
However, using your employer identification number may result in unnecessary
notices to the Requester.

   Social Security numbers (SSNs) have nine digits separated by two hyphens:
i.e. 000-00-0000. Employer identification numbers (EINs) have nine digits
separated by only one hyphen: i.e. 00-0000000.



      --------------------------------------------------------------------
      For this type of account:           Give Name and SSN of:
      --------------------------------------------------------------------
                                       
      1. Individual                       The individual
      2. Two or more individuals (joint   The actual owner of the account
         account)                         or, if combined funds, the first
                                          individual on the account(1)
      3. Custodian account of a minor     The minor(2)
         (Uniform Gift to Minors Act)
       4.  a. The usual revocable         The grantor-trustee(1)
          savings trust (grantor is
          also trustee)
           b. The so-called trust account The actual owner(1)
          that is not a legal or valid
          trust under state law
      5. Sole proprietorship              The owner(3)



- ---------------------------------------------------------------
For this type of account:                 Give Name and SSN of:
- ---------------------------------------------------------------
                                       
6. A valid trust, estate, or              The legal entity(4)
   pension trust
7. Corporation                            The corporation
8. Association, club, religious,          The organization
   charitable, educational or
   other tax-exempt organization
9. Partnership                            The partnership
10. A broker or registered                The broker or nominee
    nominee
11. Account with the Department           The public entity
    of Agriculture in the name of
    a public entity (such as a state
    or local government, school
    district, or prison that receives
    agricultural program pay-
    ments)

- --------
(1) List first and circle the name of the person whose number you furnish. If
    only one person on a joint account has a Social Security number, that
    person's number must be furnished.
(2) Circle the minor's name and furnish the minor's Social Security number.
(3) You must show your individual name, but you may also enter your business or
    "doing business as" name. You may use either your Social Security number or
    employer identification number (if you have one).
(4) List first and circle the name of the legal trust, estate or pension trust.
    (Do not furnish the taxpayer identification number of the personal
    representative or trustee unless the legal entity itself is not designated
    in the account title.)
   Note: If no name is circled when more than one name is listed, the number
   will be considered to be that of the first name listed.

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   How to Get a TIN.  If you do not have a taxpayer identification number,
apply for one immediately. To apply for a Social Security number, get Form
SS-5, Application for a Social Security Number Card, from your local Social
Security Administration office. Get Form W-7 to apply for an individual
taxpayer identification number or Form SS-4, Application for Employer
Identification Number, to apply for an employer identification number. You can
get Forms W-7 and SS-4 from the IRS.

   If you do not have a taxpayer identification number, check the "TIN Applied
For" box in Part II of the form and sign the Certificate of Awaiting Taxpayer
Identification Number, sign and date the form, and give it to the Requester.
For interest and dividend payments and certain payments made with respect to
readily tradable instruments, you will generally have 60 days to get a taxpayer
identification number and give it to the Requester. Other payments are subject
to backup withholding.

   Note:  Checking the "TIN Applied For" box means that you have already
applied for a taxpayer identification number or that you intend to apply for
one soon.

Exemption From Backup Withholding

   Payees Exempt From Backup Withholding.  Individuals (including sole
proprietors) are NOT exempt from backup withholding. Corporations are exempt
from backup withholding for certain payments, such as interest and dividends.

   For interest and dividends, the following payees are exempt from backup
withholding:

  .   A corporation;

  .   A financial institution;

  .   An organization exempt from tax under section 501(a) of the Internal
      Revenue Code of 1986, as amended (the "Code"), an individual retirement
      account (IRA), or a custodial account under section 403(b)(7) of the Code
      if the account satisfies the requirements of section 401(f)(2) of the
      Code;

  .   The United States or any of its agencies or instrumentalities;

  .   A state, the District of Columbia, a possession of the United States, or
      any of their political subdivisions or instrumentalities;

  .   A foreign government or any of its political subdivisions, agencies or
      instrumentalities;

  .   An international organization or any of its agencies or instrumentalities;

  .   A real estate investment trust;

  .   A common trust fund operated by a bank under section 584(a) of the Code;

  .   An entity registered at all times during the tax year under the
      Investment Company Act of 1940

  .   A foreign central bank of issue;

  .   A middleman known in the investment community as a nominee or who is
      listed in the most recent publication of the American Society of
      Corporate Secretaries, Inc., Nominee List; and

  .   A trust exempt from tax under section 664 of the Code or described in
      section 4947 of the Code.

   Payments Exempt From Backup Withholding.  Dividends and patronage dividends
that generally are exempt from backup withholding include:

  .   Payments to nonresident aliens subject to withholding under section 1441
      of the Code;

  .   Payments to partnerships not engaged in a trade or business in the United
      States and that have at least one nonresident alien partner;

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  .   Payments of patronage dividends not paid in money;

  .   Payments made by certain foreign organizations; and

  .   Payments made by an ESOP pursuant to section 404(k) of the Code.

   Interest payments that are generally exempt from backup withholding include:

  .   Payments of interest on obligations issued by individuals. Note, however,
      that such a payment may be subject to backup withholding if this interest
      is $600 or more and is paid in the course of the payer's trade or
      business, and you have not provided your correct taxpayer identification
      number or you have provided an incorrect taxpayer identification number
      to the payer;

  .   Payments of tax-exempt interest (including exempt-interest dividends
      under section 852 of the Code);

  .   Payments described in section 6049(b)(5) of the Code to nonresident
      aliens.

  .   Payments on tax-free covenant bonds under section 1451 of the Code; and

  .   Payments made by certain foreign organizations.

   Payments that are not subject to information reporting are also not subject
to backup withholding. For details, see sections 6041, 6041A, 6042, 6044, 6045,
6049, 6050A and 6050N of the Code, and their regulations.

   If you are exempt from backup withholding, you should still complete and
file Substitute Form W-9 to avoid possible erroneous backup withholding. Enter
your correct taxpayer identification number in Part I, check the "Exempt" box
in Part II, and sign and date the form and return it to the Requester.

   If you are a nonresident alien or a foreign entity not subject to backup
withholding, you must give the Requester a properly completed Form W-8BEN,
Certificate of Foreign Status of Beneficial Owner for United States Tax
Withholding, W-8ECI, Certificate of Foreign Person's Claim of Exemption from
Withholding on Income Effectively Connected with Conduct of a Trade or Business
in the United States, W-8EXP, Certificate of Foreign Government or Other
Foreign Organization for United States Tax Withholding or W-8IMY, Certificate
of Foreign Intermediary, Foreign Flow-Through Entity, or Certain U.S. Branches
for United States Tax Withholding. These forms can be obtained from the
Requester.

Privacy Act Notice

   Section 6109 of the Code requires you to give your correct taxpayer
identification number to persons who must file information returns with the IRS
to report interest, dividends and certain other income paid to you. The IRS
uses the numbers for identification purposes and to help verify the accuracy of
your tax return. The IRS may also provide this information to the Department of
Justice for civil and criminal litigation and to cities, states, and the
District of Columbia to carry out their tax laws. You must provide your
taxpayer identification number whether or not you are required to file a tax
return. Payers must generally withhold up to 30% of taxable interest, dividends
and certain other payments to a payee who does not furnish a taxpayer
identification number to a payer. Certain penalties may also apply.

                               -----------------

            For additional information, contact your tax consultant
                        or the Internal Revenue Service


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