
<PAGE>
 
                                                                  EXHIBIT (A)(6)

            GUIDELINES FOR CERTIFICATION OF TAXPAYER IDENTIFICATION
                         NUMBER ON SUBSTITUTE FORM W-9
 
Guidelines for Determining the Proper Identification Number to Give the Payer.
 
  Social security numbers have nine digits separated by two hyphens: i.e. 000-
00-0000. Employer identification numbers have nine digits separated by one
hyphen: i.e. 00-0000000. The table below will help determine the number to
give the payer.
 
<TABLE>
----------------------------------------------
<CAPTION>
                           Give the
For this type of account:  SOCIAL SECURITY
                           number of--
----------------------------------------------
<S>                        <C>
 1. An individual's        The individual
    account
 2. Two or more            The actual owner
    individuals (joint     of the account
    account)               or, if combined
                           funds, the first
                           individual on
                           the account(1)
 3. Husband/wife (joint    The actual owner
    account)               of the account
                           or, if joint
                           funds, either
                           person(1)
 4. Custodian account of   The minor(2)
    a minor (Uniform Gift
    to Minors Act)
 5. Adult and minor        The adult or, if
    (joint account)        the minor is the
                           only
                           contributor, the
                           minor(1)
 6. Account in the name    The ward, minor
    of guardian or         or incompetent
    committee for a        person(3)
    designated ward,
    minor or incompetent
    person
 7. a. A revocable         The grantor-
    savings trust account  trustee(1)
    (in which grantor is
    also trustee)
 b. Any "trust" account    The actual owner(1)
    that is not a legal or
    valid trust under
    State law
                                        
<CAPTION>
----------------------------------------------
                             Give the EMPLOYER
For this type of account:    IDENTIFICATION
                             number of--
----------------------------------------------
<S>                          <C>
 8. Sole proprietorship      The owner(4)
    account
 9. A valid trust, estate    The legal entity
    or pension trust         (do not furnish
                             the identifying
                             number of the
                             personal
                             representative
                             or trustee
                             unless the legal
                             entity itself is
                             not designated
                             in the account
                             title.(5)
10. Corporate account        The corporation
11. Religious, charitable,   The organization
    or educational
    organization account
12. Partnership account      The partnership
    held in the name of
    the business
13. Association, club, or    The organization
    other tax-exempt
    organization
14. A broker or registered   The broker or
    nominee                  nominee
15. Account with the         The public
    Department of            entity
    Agriculture in the
    name of a public
    entity (such as a
    State or local
    government, school
    district, or prison)
    that receives
    agricultural program
    payments.
----------------------------------------------
</TABLE>
 
(1) List first and circle the name of the person whose number you furnish.
(2) Circle the minor's name and furnish the minor's social security number.
(3) Circle the ward's, minor's or incompetent person's name and furnish such
    person's social security number.
(4) Show the name of the owner. If the owner does not have an employer
    identification number, furnish the owner's social security number.
(5) List first and circle the name of the legal trust, estate or pension
    trust.
 
NOTE: IF NO NAME IS CIRCLED WHEN THERE IS MORE THAN ONE NAME, THE NUMBER WILL
      BE CONSIDERED TO BE THAT OF THE FIRST NAME LISTED.
<PAGE>
 
            GUIDELINES FOR CERTIFICATION OF TAXPAYER IDENTIFICATION
                         NUMBER ON SUBSTITUTE FORM W-9
                                    Page 2
 
Obtaining a Number
 
If you do not have a taxpayer identification number or you do not know your
number, obtain Form SS-5, Application for a Social Security Number Card (for
resident individuals), Form SS-4, Application for Employer Identification
Number (for businesses and all other entities), Form W-7 for International
Taxpayer Identification Number (for alien individuals required to file U.S.
tax returns), at an office of the Social Security Administration or the
Internal Revenue Service.
 
To complete Substitute Form W-9, if you do not have a taxpayer identification
number, write "Applied For" in the space for the taxpayer identification
number in Part I, sign and date the Form, and give it to the requester.
Generally, you will then have 60 days to obtain a taxpayer identification
number and furnish it to the requester. If the requester does not receive your
taxpayer identification number within 60 days, backup withholding, if
applicable, will begin and will continue until you furnish your taxpayer
identification number to the requester.
 
Payees Exempt from Backup Withholding Penalties
 
Payees specifically exempted from backup withholding on ALL payments include
the following:*
 
 . A corporation.
 . A financial institution.
 . An organization exempt from tax under section 501(a), or an individual
   retirement plan ("IRA"), or a custodial account under section 403(b)(7).
 . The United States or any agency or instrumentality thereof.
 . A State, the District of Columbia, a possession of the United States, or
   any political subdivision or instrumentality thereof.
 . A foreign government or a political subdivision, agency or instrumentality
   thereof.
 . An international organization or any agency or instrumentality thereof.
 . A registered dealer in securities or commodities registered in the United
   States or a possession of the United States.
 . A real estate investment trust.
 . A common trust fund operated by a bank under section 584(a).
 . An exempt charitable remainder trust, or a non-exempt trust
   described in section 4947(a)(1).
 . An entity registered at all times during the tax year under the Investment
   Company Act of 1940.
 . A foreign central bank of issue.
 
Payments of dividends and patronage dividends not generally subject to backup
withholding include the following:
 
 . Payments to nonresident aliens subject to withholding under section 1441.
 . Payments to partnerships not engaged in a trade or business in the United
   States and that have at least one nonresident partner.
 . Payments of patronage dividends where the amount received is not paid in
   money.
 . Payments made by certain foreign organizations.
 . Payments made to a nominee.
-------
 
 * Unless otherwise noted herein, all references below to section numbers or
   to regulations are references to the Internal Revenue Code and the
   regulations promulgated thereunder.
 
Payments of interest not generally subject to backup withholding include the
following:
 
 . Payments of interest on obligations issued by individuals. Note: You may be
   subject to backup withholding if (i) this interest is $600 or more, (ii)
   the interest is paid in the course of the payer's trade or business and
   (iii) you have not provided your correct taxpayer identification number to
   the payer.
 . Payments of tax-exempt interest (including exempt-interest dividends under
   section 852).
 . Payments described in section 6049(b)(5) to non-resident aliens.
 . Payments on tax-free covenant bonds under section 1451.
 . Payments made by certain foreign organizations.
 . Payments made to a nominee.
 
Exempt payees described above should file a Substitute Form W-9 to avoid
possible erroneous backup withholding. FILE THIS FORM WITH THE PAYER, FURNISH
YOUR TAXPAYER IDENTIFICATION NUMBER, WRITE "EXEMPT" ON THE FACE OF THE FORM,
SIGN AND DATE THE FORM AND RETURN IT TO THE PAYER.
 
Certain payments other than interest, dividends and patronage dividends that
are not subject to information reporting are also not subject to backup
withholding. For details, see the regulations under sections 6041, 6041A(a),
6045, and 6050A.
 
Privacy Act Notice.--Section 6109 requires most recipients of dividends,
interest or other payments to give taxpayer identification numbers to payers
who must report the payments to the IRS. The IRS uses the numbers for
identification purposes and to help verify the accuracy of your tax return.
Payers must be given the numbers whether or not recipients are required to
file tax returns. Payers must generally withhold 31% 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.
 
Penalties
 
(1) Penalty for Failure to Furnish Taxpayer Identification Number.--If you
fail to furnish your correct taxpayer identification number to a payer, you
are subject to a penalty of $50 for each such failure unless your failure is
due to reasonable cause and not to willful neglect.
 
(2) Civil Penalty for False Statements with Respect to Withholding.--If you
make a false statement with no reasonable basis which results in no imposition
of backup withholding, you are subject to a penalty of $500.
 
(3) Criminal Penalty for Falsifying Information.--If you falsify
certifications or affirmations, you are subject to criminal penalties
including fines and/or imprisonment.
 
(4) Failure to Report Certain Dividend and Interest Payments.--If you fail to
include any portion of an includible payment for interest, dividends or
patronage dividends in gross income and such failure is due to negligence, a
penalty of 20% is imposed on any portion of any underpayment attributable to
the failure.
 
FOR ADDITIONAL INFORMATION CONTACT YOUR TAX CONSULTANT OR THE INTERNAL REVENUE
SERVICE.
 
1404-LT-99
