<PAGE>   1
                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549

                                    FORM 10-Q


[X]  QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE
     ACT OF 1934 FOR THE QUARTERLY PERIOD ENDED MARCH 31, 1998

                                       OR

[ ]  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES  
     EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM____________TO ________


                         Commission file number 0-18169

                            IEA INCOME FUND IX, L.P.
             (Exact name of registrant as specified in its charter)


           California                                       94-3069954
 (State or other jurisdiction of                          (I.R.S. Employer
 incorporation or organization)                          Identification No.)

         444 Market Street, 15th Floor, San Francisco, California 94111
               (Address of principal executive offices)   (Zip Code)

                                 (415) 677-8990
              (Registrant's telephone number, including area code)


Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 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 [X].  No [ ].


<PAGE>   2
                            IEA INCOME FUND IX, L.P.

                  REPORT ON FORM 10-Q FOR THE QUARTERLY PERIOD
                              ENDED MARCH 31, 1998

                                TABLE OF CONTENTS



<TABLE>
<CAPTION>
                                                                               PAGE
<S>                                                                            <C>
PART I - FINANCIAL INFORMATION

 Item 1. Financial Statements

         Balance Sheets - March 31, 1998 (unaudited) and December 31, 1997      4

         Statements of Operations for the three months ended March 31, 
            1998 and 1997 (unaudited)                                           5

         Statements of Cash Flows for the three months ended 
            March 31, 1998 and 1997 (unaudited)                                 6

         Notes to Financial Statements (unaudited)                              7

 Item 2. Management's Discussion and Analysis of Financial Condition and 
            Results of Operations                                               10


PART II - OTHER INFORMATION

 Item 6. Exhibits and Reports on Form 8-K                                       14
</TABLE>



                                       2
<PAGE>   3
                         PART I - FINANCIAL INFORMATION


 Item 1. Financial Statements

         Presented herein are the Registrant's balance sheets as of March 31,
         1998 and December 31, 1997, statements of operations for the three
         months ended March 31, 1998 and 1997, and statements of cash flows for
         the three months ended March 31, 1998 and 1997.



                                       3
<PAGE>   4
                            IEA INCOME FUND IX, L.P.

                                 BALANCE SHEETS

                                   (UNAUDITED)


<TABLE>
<CAPTION>
                                                                   March 31,         December 31,
                                                                      1998              1997
                                                                  ------------       ------------
<S>                                                               <C>                <C>         
                 Assets
Current assets:
   Cash and cash equivalents, includes $881,186 at March 31,
      1998 and $999,700 at December 31, 1997 in
      interest-bearing accounts                                   $    887,297       $    999,900
   Net lease receivables due from Leasing Company
      (notes 1 and 2)                                                  386,185            385,314
                                                                  ------------       ------------

         Total current assets                                        1,273,482          1,385,214
                                                                  ------------       ------------

Container rental equipment, at cost                                 15,405,791         15,717,692
   Less accumulated depreciation                                     7,472,306          7,400,531
                                                                  ------------       ------------
      Net container rental equipment                                 7,933,485          8,317,161
                                                                  ------------       ------------

                                                                  $  9,206,967       $  9,702,375
                                                                  ============       ============
            Partners' Capital

Partners' capital (deficit):
   General partner                                                $    (24,784)      $    (19,830)
   Limited partners                                                  9,231,751          9,722,205
                                                                  ------------       ------------

         Total partners' capital                                     9,206,967          9,702,375
                                                                  ------------       ------------

                                                                  $  9,206,967       $  9,702,375
                                                                  ============       ============
</TABLE>



   The accompanying notes are an integral part of these financial statements.



                                       4
<PAGE>   5
                            IEA INCOME FUND IX, L.P.

                            STATEMENTS OF OPERATIONS

                                   (UNAUDITED)


<TABLE>
<CAPTION>
                                                         Three Months Ended
                                                      -------------------------
                                                      March 31,       March 31,
                                                        1998             1997
                                                      ---------       ---------
<S>                                                   <C>             <C>      
Net lease revenue (notes 1 and 3)                     $ 414,931       $ 452,207

Other operating expenses:
  Depreciation                                          225,926         241,055
  Other general and administrative expenses              13,820           9,674
                                                      ---------       ---------
                                                        239,746         250,729
                                                      ---------       ---------

    Earnings from operations                            175,185         201,478

Other income (loss):
  Interest income                                        12,438          11,018
  Net loss on disposal of equipment                     (41,724)         (5,023)
                                                      ---------       ---------
                                                        (29,286)          5,995
                                                      ---------       ---------

    Net earnings                                      $ 145,899       $ 207,473
                                                      =========       =========

Allocation of net earnings:
  General partner                                     $  20,244       $  17,676
  Limited partners                                      125,655         189,797
                                                      ---------       ---------

                                                      $ 145,899       $ 207,473
                                                      =========       =========

Limited partners' per unit share of net earnings      $    3.70       $    5.58
                                                      =========       =========
</TABLE>



   The accompanying notes are an integral part of these financial statements.



                                       5
<PAGE>   6
                            IEA INCOME FUND IX, L.P.

                            STATEMENTS OF CASH FLOWS

                                   (UNAUDITED)


<TABLE>
<CAPTION>
                                                           Three Months Ended
                                                        -------------------------
                                                         March 31,      March 31,
                                                           1998           1997
                                                        ---------       ---------
<S>                                                     <C>             <C>      
Net cash provided by operating activities               $ 370,993       $ 470,282

Cash flows provided by investing activities:
  Proceeds from sale of container rental equipment        157,711          47,876

Cash flows used in financing activities:
  Distribution to partners                               (641,307)       (557,275)
                                                        ---------       ---------


Net decrease in cash and cash equivalents                (112,603)        (39,117)


Cash and cash equivalents at January 1                    999,900         936,081
                                                        ---------       ---------


Cash and cash equivalents at March 31                   $ 887,297       $ 896,964
                                                        =========       =========
</TABLE>


   The accompanying notes are an integral part of these financial statements.



                                       6
<PAGE>   7
                            IEA INCOME FUND IX, L.P.

                     NOTES TO UNAUDITED FINANCIAL STATEMENTS



(1)  Summary of Significant Accounting Policies

     (a) Nature of Operations

         IEA Income Fund IX, L.P. (the "Partnership") is a limited partnership
         organized under the laws of the State of California on June 8, 1988 for
         the purpose of owning and leasing marine cargo containers. Cronos
         Capital Corp. ("CCC") is the general partner and, with its affiliate
         Cronos Containers Limited (the "Leasing Company"), manages the business
         of the Partnership. The Partnership shall continue until December 31,
         2009, unless sooner terminated upon the occurrence of certain events.

         The Partnership commenced operations on December 5, 1988, when the
         minimum subscription proceeds of $1,000,000 were obtained. The
         Partnership offered 40,000 units of limited partnership interest at
         $500 per unit, or $20,000,000. The offering terminated on September 11,
         1989, at which time 33,992 limited partnership units had been
         purchased.

         As of March 31, 1998, the Partnership operated 2,077 twenty-foot, 706
         forty-foot and 1,352 forty-foot high-cube marine dry cargo containers.

     (b) Leasing Company and Leasing Agent Agreement

         Pursuant to the Limited Partnership Agreement of the Partnership, all
         authority to administer the business of the Partnership is vested in
         CCC. CCC has entered into a Leasing Agent Agreement whereby the Leasing
         Company has the responsibility to manage the leasing operations of all
         equipment owned by the Partnership. Pursuant to the Agreement, the
         Leasing Company is responsible for leasing, managing and re-leasing the
         Partnership's containers to ocean carriers and has full discretion over
         which ocean carriers and suppliers of goods and services it may deal
         with. The Leasing Agent Agreement permits the Leasing Company to use
         the containers owned by the Partnership, together with other containers
         owned or managed by the Leasing Company and its affiliates, as part of
         a single fleet operated without regard to ownership. Since the Leasing
         Agent Agreement meets the definition of an operating lease in Statement
         of Financial Accounting Standards (SFAS) No. 13, it is accounted for as
         a lease under which the Partnership is lessor and the Leasing Company
         is lessee.

         The Leasing Agent Agreement generally provides that the Leasing Company
         will make payments to the Partnership based upon rentals collected from
         ocean carriers after deducting direct operating expenses and management
         fees to CCC. The Leasing Company leases containers to ocean carriers,
         generally under operating leases which are either master leases or term
         leases (mostly two to five years). Master leases do not specify the
         exact number of containers to be leased or the term that each container
         will remain on hire but allow the ocean carrier to pick up and drop off
         containers at various locations; rentals are based upon the number of
         containers used and the applicable per-diem rate. Accordingly, rentals
         under master leases are all variable and contingent upon the number of
         containers used. Most containers are leased to ocean carriers under
         master leases; leasing agreements with fixed payment terms are not
         material to the financial statements. Since there are no material
         minimum lease rentals, no disclosure of minimum lease rentals is
         provided in these financial statements.




                                       7
<PAGE>   8
                            IEA INCOME FUND IX, L.P.

                     NOTES TO UNAUDITED FINANCIAL STATEMENTS


     (c) Basis of Accounting

         The Partnership utilizes the accrual method of accounting. Net lease
         revenue is recorded by the Partnership in each period based upon its
         leasing agent agreement with the Leasing Company. Net lease revenue is
         generally dependent upon operating lease rentals from operating lease
         agreements between the Leasing Company and its various lessees, less
         direct operating expenses and management fees due in respect of the
         containers specified in each operating lease agreement.

     (d) Financial Statement Presentation

         These financial statements have been prepared without audit. Certain
         information and footnote disclosures normally included in financial
         statements prepared in accordance with generally accepted accounting
         procedures have been omitted. It is suggested that these financial
         statements be read in conjunction with the financial statements and
         accompanying notes in the Partnership's latest annual report on Form
         10-K.

         The preparation of financial statements in conformity with generally
         accepted accounting principles (GAAP) requires the Partnership to make
         estimates and assumptions that affect the reported amounts of assets
         and liabilities and disclosure of contingent assets and liabilities at
         the date of the financial statements and the reported amounts of
         revenues and expenses during the reported period. Actual results could
         differ from those estimates.

         The interim financial statements presented herewith reflect all
         adjustments of a normal recurring nature which are, in the opinion of
         management, necessary to a fair statement of the financial condition
         and results of operations for the interim periods presented.


(2)  Net Lease Receivables Due from Leasing Company

     Net lease receivables due from the Leasing Company are determined by
     deducting direct operating payables and accrued expenses, base management
     fees payable, and reimbursed administrative expenses payable to CCC and its
     affiliates from the rental billings payable by the Leasing Company to the
     Partnership under operating leases to ocean carriers for the containers
     owned by the Partnership. Net lease receivables at March 31, 1998 and
     December 31, 1997 were as follows:


<TABLE>
<CAPTION>
                                                                           March 31,    December 31,
                                                                              1998          1997
                                                                            --------      --------
<S>                                                                        <C>          <C>
         Lease receivables, net of doubtful accounts of
            $72,029 at March 31, 1998 and $41,626 at December 31, 1997      $635,785      $666,274

         Less:
         Direct operating payables and accrued expenses                      140,361       153,087
         Damage protection reserve                                            52,181        60,973
         Base management fees                                                 46,062        55,062
         Reimbursed administrative expenses                                   10,996        11,838
                                                                            --------      --------

                                                                            $386,185      $385,314
                                                                            ========      ========
</TABLE>



                                       8
<PAGE>   9
                            IEA INCOME FUND IX, L.P.

                     NOTES TO UNAUDITED FINANCIAL STATEMENTS


(3)  Net Lease Revenue

     Net lease revenue is determined by deducting direct operating expenses,
     base management fees and reimbursed administrative expenses to CCC from the
     rental revenue billed by the Leasing Company under operating leases to
     ocean carriers for the containers owned by the Partnership. Net lease
     revenue for the three-month periods ended March 31, 1998 and 1997 was as
     follows:


<TABLE>
<CAPTION>
                                                     Three Months Ended
                                                  ------------------------
                                                   March 31,     March 31,
                                                    1998          1997
                                                  --------      --------
<S>                                               <C>           <C>     
         Rental revenue                           $607,334      $678,072
         Less:
         Rental equipment operating expenses       110,359       144,799
         Base management fees                       42,237        46,954
         Reimbursed administrative expenses         39,807        34,112
                                                  --------      --------

                                                  $414,931      $452,207
                                                  ========      ========
</TABLE>




                                       9
<PAGE>   10
Item 2. Management's Discussion and Analysis of Financial Condition and Results
        of Operations

It is suggested that the following discussion be read in conjunction with the
Registrant's most recent annual report on Form 10-K.

1)   Material changes in financial condition between March 31, 1998 and December
     31, 1997.

     During the first three months of 1998, the Registrant disposed of 84
     containers as part of its ongoing container operations. At March 31, 1998,
     87% of the original equipment remained in the Registrant's fleet, as
     compared to 88% at December 31, 1997, and was comprised of the following:


<TABLE>
<CAPTION>
                                                               40-Foot
                                        20-Foot    40-Foot    High-Cube
                                        -------    -------    ---------
<S>                                     <C>        <C>        <C>
         Containers on lease:
              Term leases                  146         50        148
              Master leases              1,529        500        999
                                         -----      -----      -----
                 Subtotal                1,675        550      1,147

         Containers off lease              402        156        205
                                         -----      -----      -----

              Total container fleet      2,077        706      1,352
                                         =====      =====      =====
</TABLE>

<TABLE>
<CAPTION>

                                                                                                 40-Foot
                                                     20-Foot                40-Foot              High-Cube
                                                ----------------       ---------------        ----------------
                                                Units        %         Units        %         Units        %
                                                -----      -----       -----      -----       -----      -----
<S>                                             <C>          <C>         <C>        <C>       <C>          <C> 
         Total purchases                        2,327        100%        799        100%      1,653        100%
             Less disposals                       250         11%         93         12%        301         18%
                                                -----      -----       -----      -----       -----      -----

         Remaining fleet at March 31, 1998      2,077         89%        706         88%      1,352         82%
                                                =====      =====       =====      =====       =====      =====
</TABLE>



     During the first quarter of 1998, distributions from operations and sales
     proceeds amounted to $641,307, reflecting distributions to the general and
     limited partners for the fourth quarter of 1997. This represents an
     increase from the $587,657 distributed during the fourth quarter of 1997,
     reflecting distributions for the third quarter of 1997. The increase in
     distributions is attributable to an increase in sales proceeds distributed
     to its partners.

     Market conditions that existed during 1997 persisted through the first
     quarter of 1998. Low container prices, favorable interest rates and the
     abundance of available capital continued to discourage ocean carriers and
     other transport companies from leasing containers at levels comparable to
     previous years. By the end of 1997, the volatility of the Hong Kong and
     other Asian financial markets began to negatively impact trade, shipping
     and container leasing. As a result, the Registrant's container utilization
     rate declined from 84% at December 31, 1997 to 82% at March 31, 1998.
     Per-diem rental rates continued to remain under pressure as a result of the
     following factors: start-up leasing companies offering new containers and
     low rental rates in an effort to break into the leasing market; established
     leasing companies reducing rates to very low levels; and a continuing
     oversupply of containers. These leasing market conditions impacted the
     Registrant's financial condition and operating performance during the first
     quarter of 1998.



                                       10
<PAGE>   11
2)   Material changes in the results of operations between the three-month
     period ended March 31, 1998 and the three-month period ended March 31,
     1997.

     Net lease revenue for the three-month period ended March 31, 1998 was
     $414,931, a decline of approximately 8% from the same three-month period in
     the prior year. Gross rental revenue (a component of net lease revenue) for
     the three-month period ended March 31, 1998 was $607,334, a decline of 10%
     from the same three-month period in 1997. Gross rental revenue was
     primarily impacted by a slightly smaller fleet size and lower per-diem
     rental rates. Average per-diem rental rates for the three-month period
     ended March 31, 1998 declined 9% when compared to the same three-month
     period in the prior year. The Registrant's average fleet size and
     utilization rates for the three-month periods ended March 31, 1998 and 1997
     were as follows:


<TABLE>
<CAPTION>
                                                          Three Months Ended
                                                         ---------------------
                                                         March 31,   March 31,
                                                           1998        1997
                                                         ---------   ---------
<S>                                                      <C>         <C>
         Average fleet size (measured in twenty-foot
            equivalent units (TEU))                       6,252       6,658
         Average Utilization                                 82%         79%
</TABLE>


     The Registrant's declining fleet size contributed to a 6% decline in
     depreciation expense when compared to the same three-month period in the
     prior year. Rental equipment operating expenses were 18% of the
     Registrant's gross lease revenue during the three-month period ended March
     31, 1998, as compared to 21% during the three-month period ended March 31,
     1997.

     As reported in the Registrant's Current Report on Form 8-K and Amendment
     No. 1 to Current Report on Form 8-K, filed with the Commission on February
     7, 1997 and February 26, 1997, respectively, Arthur Andersen, London,
     England, resigned as auditors of The Cronos Group, a Luxembourg Corporation
     headquartered in Orchard Lea, England (The "Parent Company"), on February
     3, 1997.

     The Parent Company is the indirect corporate parent of CCC, the General
     Partner of the Registrant. In its letter of resignation to the Parent
     Company, Arthur Andersen stated that it resigned as auditors of the Parent
     Company and all other entities affiliated with the Parent Company. While
     its letter of resignation was not addressed to CCC, Arthur Andersen
     confirmed to CCC that its resignation as auditors of the entities referred
     to in its letter of resignation included its resignation as auditors of CCC
     and the Registrant.

     CCC does not believe, based upon the information currently available to it,
     that Arthur Andersen's resignation was triggered by any concern over the
     accounting policies and procedures followed by the Registrant.

     Arthur Andersen's report on the financial statements of CCC and the
     Registrant, for years preceding 1996, has not contained an adverse opinion
     or a disclaimer of opinion, nor was any such report qualified or modified
     as to uncertainty, audit scope, or accounting principles.

     During the Registrant's 1995 fiscal year and the subsequent interim period
     preceding Arthur Andersen's resignation, there were no disagreements
     between CCC or the Registrant and Arthur Andersen on any matter of
     accounting principles or practices, financial statement disclosure, or
     auditing scope or procedure.

     The Registrant retained a new auditor, Moore Stephens, P.C. on April 10,
     1997, as reported in its Current Report on Form 8-K, filed April 14, 1997.



                                       11
<PAGE>   12
     In connection with its resignation, Arthur Andersen also prepared a report
     pursuant to the provisions of Section 10A(b)(2) of the Securities Exchange
     Act of 1934, as amended, for filing by the Parent Company with the
     Securities and Exchange Commission (the "SEC"). Following the report of
     Arthur Andersen, the SEC, on February 10, 1997, commenced a private
     investigation of the Parent Company for the purpose of investigating the
     matters discussed in such report and related matters. The Registrant does
     not believe that the focus of the SEC's investigation is upon the
     Registrant or CCC. CCC is unable to predict the outcome of the SEC's
     ongoing private investigation of the Parent Company.

     In 1993, the Parent Company negotiated a credit facility (herinafter, the
     "Credit Facility") with several banks for the use of the Parent Company and
     its affiliates, including CCC. At December 31, 1996, approximately
     $73,500,000 in principal indebtedness was outstanding under the Credit
     Facility. As a party to the Credit Facility, CCC is jointly and severally
     liable for the repayment of all principal and interest owed under the
     Credit Facility. The obligations of CCC, and the five other subsidiaries of
     the Parent Company that are borrowers under the Credit Facility, are
     guaranteed by the Parent Company.

     Following negotiations in 1997 with the banks providing the Credit
     Facility, an Amended and Restated Credit Agreement was executed in June
     1997, subject to various actions being taken by the Parent Company and its
     subsidiaries, primarily relating to the provision of additional collateral.
     This Agreement was further amended in July 1997 and the provisions of the
     Agreement and its Amendment converted the facility to a term loan, payable
     in installments, with a final maturity date of May 31, 1998. At December
     31, 1997, approximately $37,600,000 was outstanding under the Credit
     Facility.

     The terms of the Agreement and its Amendment also provide for additional
     security over shares in the subsidiary of the Parent Company that owns the
     head office of the Parent Company's container leasing operations. They also
     provided for the loans to Stefan M. Palatin, the Chairman of the Parent
     Company (the "Chairman") and its Chief Executive Officer (and a Director of
     CCC), of approximately $5,990,000 and $3,700,000 (totaling approximately
     $9,690,000) to be restructured as obligations of the Chairman to another
     subsidiary of the Parent Company. These obligations have been collaterally
     assigned to the lending banks, together with the pledge of 1,000,000 shares
     of the Parent Company's Common Stock owned by the Chairman. These 1,000,000
     shares represent 11% of the issued and outstanding shares of Common Stock
     of the Parent Company as of December 31, 1997. The shares of the Parent
     Company are traded on NASDAQ (CRNSF). (The Chairman, including the
     1,000,000 shares pledged to the banks, owns approximately 55% of the issued
     and outstanding shares of Common Stock of the Parent Company as of December
     31, 1997). Additionally, CCC granted the lending banks a security interest
     in the fees to which it is entitled for the services it renders to the
     container leasing partnerships of which it acts as general partner,
     including its fee income payable by the Registrant.

     The lending banks have indicated that they will not renew the Credit
     Facility, and the Parent Company has yet to secure a source for repayment
     of the balance due under the Credit Facility at May 31, 1998. CCC is
     currently in discussions with the management of the Parent Company to
     provide assurance that the management of the container leasing partnerships
     managed by CCC, including the Registrant, is not disrupted pending a
     refinancing or reorganization of the indebtedness of the Parent Company and
     its affiliates.

     The Registrant is not a borrower under the Credit Facility, and neither the
     containers nor the other assets of the Registrant have been pledged as
     collateral under the Credit Facility.

     The Registrant is unable to determine the impact, if any, these concerns
     may have on the future operating results and financial condition of the
     Registrant or CCC and the Leasing Company's ability to manage the
     Registrant's fleet in subsequent periods.



                                       12
<PAGE>   13
     Year 2000

     The Registrant relies upon the financial and operational systems provided
     by the Leasing company and its affiliates, as well as the systems provided
     by other independent third parties to service the three primary areas of
     its business: investor processing/maintenance; container leasing/asset
     tracking; and accounting finance. The Registrant has received confirmation
     from its third-party investor processing/maintenance vendor that their
     system is Year 2000 compliant. The Registrant does not expect a material
     increase in it vendor servicing fee to reimburse Year 2000 costs. Container
     leasing/asset tracking and accounting/finance services are provided to the
     Registrant by CCC and its affiliate, Cronos Containers Limited (the
     "Leasing Company"), pursuant to the respective Limited Partnership
     Agreement and Leasing Agent Agreement. CCC and the Leasing Company have
     initiated a program to prepare their systems and applications for the Year
     2000. Preliminary studies indicate that testing, conversion and upgrading
     of system applications is expected to cost CCC and the Leasing Company less
     than $500,000. Pursuant to the Limited Partnership Agreement, CCC or the
     Leasing Company, may not seek reimbursement of data processing costs
     associated with the Year 2000 program. The financial impact of making these
     required system changes is not expected to be material to the Registrant's
     financial position, results of operations or cash flows.

     Cautionary Statement

     This Quarterly Report on Form 10-Q contains statements relating to future
     results of the Registrant, including certain projections and business
     trends, that are "forward-looking statements" as defined in the Private
     Securities Litigation Reform Act of 1995. Actual results may differ
     materially from those projected as a result of certain risks and
     uncertainties, including but not limited to changes in: economic
     conditions; trade policies; demand for and market acceptance of leased
     marine cargo containers; competitive utilization and per-diem rental rate
     pressures; as well as other risks and uncertainties, including but not
     limited to those described in the above discussion of the marine container
     leasing business under Item 2., Management's Discussion and Analysis of
     Financial Condition and Results of Operations; and those detailed from time
     to time in the filings of Registrant with the Securities and Exchange
     Commission.



                                       13
<PAGE>   14
                           PART II - OTHER INFORMATION


Item 6.  Exhibits and Reports on Form 8-K

(a)  Exhibits

<TABLE>
<CAPTION>
 Exhibit
    No.                     Description                         Method of Filing
 --------                   -----------                         ----------------
<S>        <C>                                                  <C>
   3(a)    Limited Partnership Agreement of the Registrant,     *
           amended and restated as of September 12, 1988

   3(b)    Certificate of Limited Partnership of the            **
           Registrant

   27      Financial Data Schedule                              Filed with this document
</TABLE>


(b)  Reports on Form 8-K

     No reports on Form 8-K were filed by the Registrant during the quarter
ended March 31, 1998.




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

*    Incorporated by reference to Exhibit "A" to the Prospectus of the
     Registrant dated September 12, 1988, included as part of Registration
     Statement on Form S-1 (No. 33-23321)

**   Incorporated by reference to Exhibit 3.4 to the Registration Statement on
     Form S-1 (No. 33-23321)



                                       14
<PAGE>   15
                                   SIGNATURES


        Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this Report to be signed on its behalf by the
undersigned thereunto duly authorized.



                                  IEA INCOME FUND IX, L.P.

                                  By   Cronos Capital Corp.
                                       The General Partner



                                  By    /s/ Dennis J. Tietz
                                       ----------------------------------------
                                       Dennis J. Tietz
                                       President and Director of Cronos 
                                       Capital Corp. ("CCC")
                                       Principal Executive Officer of CCC



Date: May 15, 1998



                                       15
<PAGE>   16
                                  EXHIBIT INDEX



<TABLE>
<CAPTION>
Exhibit
   No.                     Description                         Method of Filing
-------                    -----------                         ----------------
<S>       <C>                                                  <C>
  3(a)    Limited Partnership Agreement of the Registrant,     *
          amended and restated as of September 12, 1988

  3(b)    Certificate of Limited Partnership of the            **
          Registrant

  27      Financial Data Schedule                              Filed with this document
</TABLE>



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

*    Incorporated by reference to Exhibit "A" to the Prospectus of the
     Registrant dated September 12, 1988, included as part of Registration
     Statement on Form S-1 (No. 33-23321)

**   Incorporated by reference to Exhibit 3.4 to the Registration Statement on
     Form S-1 (No. 33-23321)