<PAGE>   1

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                       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 SEPTEMBER 30, 1999

                                       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)

<TABLE>
<S>                                            <C>
                  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)
</TABLE>

                                 (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 [ ]

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<PAGE>   2

                            IEA INCOME FUND IX, L.P.

                  REPORT ON FORM 10-Q FOR THE QUARTERLY PERIOD
                            ENDED SEPTEMBER 30, 1999

                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                          PAGE
                                                                          ----
<S>       <C>                                                             <C>
PART I -- FINANCIAL INFORMATION
Item 1.   Financial Statements
          Balance Sheets -- September 30, 1999 (unaudited) and
          December 31, 1998...........................................      4
          Statements of Operations for the three and nine months ended
          September 30, 1999 and 1998 (unaudited).....................      5
          Statements of Cash Flows for the nine months ended September
          30, 1999 and 1998 (unaudited)...............................      6
          Notes to Financial Statements (unaudited)...................      7
Item 2.   Management's Discussion and Analysis of Financial Condition
          and Results of Operations...................................     10
Item 3.   Quantitative and Qualitative Disclosures About Market
          Risk........................................................     12

PART II -- OTHER INFORMATION
Item 1.   Legal Proceedings...........................................     13
Item 3.   Defaults Upon Senior Securities.............................     13
Item 5.   Other Information...........................................     13
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 September 30,
1999 and December 31, 1998, statements of operations for the three and nine
months ended September 30, 1999 and 1998, and statements of cash flows for the
nine months ended September 30, 1999 and 1998.

                                        3
<PAGE>   4

                            IEA INCOME FUND IX, L.P.

                                 BALANCE SHEETS
                                  (UNAUDITED)


<TABLE>
<CAPTION>

                                                              SEPTEMBER 30,    DECEMBER 31,
                                                                  1999             1998
                                                              -------------    ------------
<S>                                                           <C>              <C>
                                     ASSETS

Current assets:
  Cash and cash equivalents, includes $673,541 at September
     30, 1999 and $780,329 at December 31, 1998 in
     interest-bearing accounts..............................   $   673,641     $   780,429
  Net lease receivables due from Leasing Company (notes 1
     and 2).................................................       109,355         229,107
                                                               -----------     -----------
          Total current assets..............................       782,996       1,009,536
                                                               -----------     -----------
Container rental equipment, at cost.........................    13,158,013      14,429,687
  Less accumulated depreciation.............................     7,478,996       7,605,099
                                                               -----------     -----------
     Net container rental equipment.........................     5,679,017       6,824,588
                                                               -----------     -----------
                                                               $ 6,462,013     $ 7,834,124
                                                               ===========     ===========

                               PARTNERS' CAPITAL
Partners' capital (deficit):
  General partner...........................................   $   (52,234)    $   (38,512)
  Limited partners..........................................     6,514,247       7,872,636
                                                               -----------     -----------
          Total partners' capital...........................     6,462,013       7,834,124
                                                               -----------     -----------
                                                               $ 6,462,013     $ 7,834,124
                                                               ===========     ===========
</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                NINE MONTHS ENDED
                                         ------------------------------    ------------------------------
                                         SEPTEMBER 30,    SEPTEMBER 30,    SEPTEMBER 30,    SEPTEMBER 30,
                                             1999             1998             1999             1998
                                         -------------    -------------    -------------    -------------
<S>                                      <C>              <C>              <C>              <C>
Net lease revenue (notes 1 and 3)......    $ 287,550        $388,080         $ 886,342       $1,229,403
Other operating expenses:
  Depreciation.........................      193,834         219,303           605,292          667,208
  Other general and administrative
     expenses..........................        9,338          14,232            31,618           38,118
                                           ---------        --------         ---------       ----------
                                             203,172         233,535           636,910          705,326
                                           ---------        --------         ---------       ----------
     Earnings from operations..........       84,378         154,545           249,432          524,077
Other income (loss):
  Interest income......................        6,936          10,244            22,734           34,492
  Net loss on disposal of equipment....     (105,519)        (65,293)         (172,479)        (135,300)
                                           ---------        --------         ---------       ----------
                                             (98,583)        (55,049)         (149,745)        (100,808)
                                           ---------        --------         ---------       ----------
     Net earnings (loss)...............    $ (14,205)       $ 99,496         $  99,687       $  423,269
                                           =========        ========         =========       ==========
Allocation of net earnings (loss):
  General partner......................    $  11,934        $ 19,780         $  45,276       $   60,587
  Limited partners.....................      (26,139)         79,716            54,411          362,682
                                           ---------        --------         ---------       ----------
                                           $ (14,205)       $ 99,496         $  99,687       $  423,269
                                           =========        ========         =========       ==========
Limited partners' per unit share of net
  earnings (loss)......................    $   (0.77)       $   2.35         $    1.60       $    10.67
                                           =========        ========         =========       ==========
</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>
                                                                    NINE MONTHS ENDED
                                                              ------------------------------
                                                              SEPTEMBER 30,    SEPTEMBER 30,
                                                                  1999             1998
                                                              -------------    -------------
<S>                                                           <C>              <C>
Net cash provided by operating activities...................   $   985,104      $ 1,222,525
Cash flows provided by investing activities:
  Proceeds from sale of container rental equipment..........       379,906          408,598
Cash flows used in financing activities:
  Distribution to partners..................................    (1,471,798)      (1,848,811)
                                                               -----------      -----------
Net decrease in cash and cash equivalents...................      (106,788)        (217,688)
Cash and cash equivalents at January 1......................       780,429          999,900
                                                               -----------      -----------
Cash and cash equivalents at September 30...................   $   673,641      $   782,212
                                                               ===========      ===========
</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 September 30, 1999, the Partnership owned and operated 1,768
twenty-foot, 617 forty-foot and 1,142 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.

     (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.

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

              NOTES TO UNAUDITED FINANCIAL STATEMENTS (CONTINUED)

     (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 September 30, 1999 and December 31,
1998 were as follows:

<TABLE>
<CAPTION>
                                                             SEPTEMBER 30,    DECEMBER 31,
                                                                 1999             1998
                                                             -------------    ------------
<S>                                                          <C>              <C>
Lease receivables, net of doubtful accounts of $60,252 at
  September 30, 1999 and $75,951 at December 31, 1998......    $410,984         $524,138
Less:
Direct operating payables and accrued expenses.............     192,853          177,061
Damage protection reserve..................................      48,515           51,003
Base management fees.......................................      53,624           56,982
Reimbursed administrative expenses.........................       6,637            9,985
                                                               --------         --------
                                                               $109,355         $229,107
                                                               ========         ========
</TABLE>

(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 and nine-month periods ended September 30, 1999 and 1998 was as follows:

<TABLE>
<CAPTION>
                                               THREE MONTHS ENDED                NINE MONTHS ENDED
                                         ------------------------------    ------------------------------
                                         SEPTEMBER 30,    SEPTEMBER 30,    SEPTEMBER 30,    SEPTEMBER 30,
                                             1999             1998             1999             1998
                                         -------------    -------------    -------------    -------------
<S>                                      <C>              <C>              <C>              <C>
Rental revenue (note 4)................    $415,184         $589,300        $1,322,474       $1,780,917
Less:
Rental equipment operating expenses....      80,286          124,572           270,348          324,500
Base management fees...................      29,626           41,920            99,586          124,284
Reimbursed administrative expenses.....      17,722           34,728            66,198          102,730
                                           --------         --------        ----------       ----------
                                           $287,550         $388,080        $  886,342       $1,229,403
                                           ========         ========        ==========       ==========
</TABLE>

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

              NOTES TO UNAUDITED FINANCIAL STATEMENTS (CONTINUED)

(4) OPERATING SEGMENT

     The Financial Accounting Standards Board has issued SFAS No. 131,
"Disclosures about Segments of an Enterprise and Related Information," which
changes the way public business enterprises report financial and descriptive
information about reportable operating segments. An operating segment is a
component of an enterprise that engages in business activities from which it may
earn revenues and incur expenses, whose operating results are regularly reviewed
by the enterprise's chief operating decision maker to make decisions about
resources to be allocated to the segment and assess its performance, and about
which separate financial information is available. Management operates the
Partnership's container fleet as a homogenous unit and has determined, after
considering the requirements of SFAS No. 131, that as such it has a single
reportable operating segment.

     The Partnership derives its revenues from owning and leasing marine cargo
containers. As of September 30, 1999, the Partnership operated 1,768
twenty-foot, 617 forty-foot and 1,142 forty-foot high-cube marine dry cargo
containers.

     Due to the Partnership's lack of information regarding the physical
location of its fleet of containers when on lease in the global shipping trade,
it is impracticable to provide the geographic area information required by SFAS
No. 131. Any attempt to separate "foreign" operations from "domestic" operations
would be dependent on definitions and assumptions that are so subjective as to
render the information meaningless and potentially misleading.

                                        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 September 30, 1999 and
December 31, 1998.

     During the first nine months of 1999, the Registrant disposed of 365
containers as part of its ongoing container operations. At September 30, 1999,
74% of the original equipment remained in the Registrant's fleet, as compared to
81% at December 31, 1998, 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..........................................     170        98          208
  Master leases........................................   1,171       352          737
                                                          -----       ---        -----
     Subtotal..........................................   1,341       450          945
Containers off lease...................................     427       167          197
                                                          -----       ---        -----
          Total container fleet........................   1,768       617        1,142
                                                          =====       ===        =====
</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................................    559    24%    182     23%     511    31%
                                                -----   ---     ---    ---    -----   ---
Remaining fleet at September 30, 1999.........  1,768    76%    617     77%   1,142    69%
                                                =====   ===     ===    ===    =====   ===
</TABLE>

     During the third quarter of 1999, distributions from operations and sales
proceeds amounted to $409,203, reflecting distributions to the general and
limited partners for the second quarter of 1999. This represents a decline from
the $529,491 distributed during the second quarter of 1999, reflecting
distributions for the first quarter of 1999.

     As discussed in previous quarters, improving prospects in the Asia-Pacific
region have been the impetus for a recovery in containerized trade volumes.
Strong demand in North America has generated increases in transpacific volumes
from Asia, and imports into Asia are also improving as a result of economic
recovery in the region. As a result, container lease-outs from both North
America and Europe are showing signs of revival.

     The General Partner previously reported that trade imbalances, which were
heightened by the Asian financial crisis, resulted in the necessity to
reposition off-hire equipment from low-demand drop-off locations in North
America and Europe to higher-demand areas in Asia. Such imbalances continue to
be widespread in the container leasing industry. In order to meet the stronger
demand in Asia, the General Partner will continue to reposition the Registrant's
idle equipment as warranted by market conditions. This repositioning will allow
us to better fulfill customer requirements, while at the same time reducing
costs associated with handling and storing off-hire or stockpiled equipment.

     (2) Material changes in the results of operations between the three and
nine-month periods ended September 30, 1999 and the three and nine-month
periods ended September 30, 1998.

     Net lease revenue for the three and nine-month periods ended September 30,
1999 was $287,550 and $886,342, respectively, a decline of 26% and 28% from the
respective three and nine-month periods in the prior year. Gross rental revenue
(a component of net lease revenue) for the three and nine-month periods ended
September 30, 1999 was $415,184 and $1,322,474, respectively, a decline of 30%
and 26% from the same respective three and nine-month periods in 1998. 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 and
nine-month periods ended September 30, 1999 declined 16% and 10%, respectively,
when compared to the same three and

                                       10
<PAGE>   11

nine-month periods in the prior year. The Registrant's average fleet size and
utilization rates for the three and nine-month periods ended September 30, 1999
and 1998 were as follows:

<TABLE>
<CAPTION>
                                                    THREE MONTHS ENDED               NINE MONTHS ENDED
                                               -----------------------------   -----------------------------
                                               SEPTEMBER 30,   SEPTEMBER 30,   SEPTEMBER 30,   SEPTEMBER 30,
                                                   1999            1998            1999            1998
                                               -------------   -------------   -------------   -------------
<S>                                            <C>             <C>             <C>             <C>
Average fleet size (measured in twenty-foot
  equivalent units (TEU))....................      5,366           5,972           5,541           6,127
Average Utilization..........................         78%             81%             78%             82%
</TABLE>

     The Registrant's diminishing fleet contributed to a decrease of 12% and 9%,
respectively, in depreciation expense when compared to the same three and
nine-month periods in the prior year. Rental equipment operating expenses were
19% and 20%, respectively, of the Registrant's gross lease revenue during the
three and nine-month periods ended September 30, 1999, as compared to 21% and
18%, respectively, of the Registrant's gross lease revenue during the three and
nine-month periods ended September 30, 1998.

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 Leasing Company's computer systems have undergone
modifications in order to render the systems ready for the Year 2000. The
Leasing Company has completed a detailed inventory of all software and hardware
systems and has identified all components that need to be modified. The Leasing
Company has completed all the necessary changes and testing in a dedicated Year
2000 environment. All compliant code was made live in August 1999. The Leasing
Company has contacted all of its critical business suppliers and has been
advised that their systems are Year 2000 compliant. The Leasing Company has also
confirmed the compliance of its suppliers' products through its own extensive
testing. Expenses associated with addressing Year 2000 issues are being
recognized as incurred. Management has not yet assessed the Year 2000 compliance
expense but does not anticipate the costs incurred to date or to be incurred in
the future by the Leasing Company and its affiliates to be in excess of
$500,000. None of the costs incurred with respect to Year 2000 compliance will
be borne by the Registrant. The Leasing Company believes it will be able to
resolve any major Year 2000 issues. The Leasing Company is aware of the
implications of a Year 2000 computer system failure and is currently in the
process of developing its contingency plans. While management believes the
possibility of a Year 2000 system failure to be remote, if the Leasing Company's
internal systems or those of its critical business suppliers fail, the Leasing
Company's consolidated financial position, liquidity or results of operations
may be adversely affected.

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, including, without limitation, (a) the statements
in Management's Discussion and Analysis of Financial Condition and Results of
Operations concerning (i) preliminary indications that trade volumes from North
America and Europe to Asia may be increasing (ii) the Leasing Company's
expectation that its repositioning strategy will place container equipment in
higher demand locations and that it will improve utilization; (b) the statements
under Year 2000 concerning (i) the Leasing Company's belief that it will be able
to resolve any major year 2000 issues (ii) the Leasing Company's belief that the
possibility of a year 2000 failure is remote; and (c) the statements under Legal
Proceedings concerning the Parent Company's hope of settling the SEC
investigation by the end of 1999.

     Forward-looking statements are based upon management's current expectations
and beliefs concerning future developments and their potential effects upon the
Registrant. There can be no assurance that future developments will be in
accordance with management's expectations or that the effect of future
developments on the Registrant will be those anticipated by management. Actual
results may differ materially from those projected as a result of certain risks
and uncertainties, including, but not limited to, changes in: economic

                                       11
<PAGE>   12

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 under Item 2, Management's Discussion and Analysis of Financial
Condition and Results of Operations in the discussion of the marine container
leasing business; Item 3, Quantitative and Qualitative Disclosures about Market
Risk and under Part II -- Item 1, Legal Proceedings and Item 5, Other
Information and those risks and uncertainties detailed from time to time in the
filings of the Registrant with the Securities and Exchange Commission.

ITEM 3. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

     Not applicable.

                                       12
<PAGE>   13

                          PART II -- OTHER INFORMATION

ITEM 1. LEGAL PROCEEDINGS

     As the Registrant has previously reported, in February 1997, its former
outside auditors, Arthur Andersen LLP ("Arthur Andersen"), resigned as auditors
to The Cronos Group (the "Parent Company"), its subsidiaries, and all other
entities affiliated with the Parent Company, including the Registrant. The
Parent Company is the indirect corporate parent of CCC, the managing general
partner of 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 reports on the financial statements of CCC and the
Registrant, for years preceding 1996, had not contained an adverse opinion or a
disclaimer of opinion, nor were any such reports qualified or modified as to
uncertainty, audit scope, or accounting principles.

     During the Registrant's fiscal year ended December 31, 1995, 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.

     In connection with its resignation, Arthur Andersen prepared a report
pursuant to Section 10A of the Securities Exchange Act of 1934, as amended, for
filing by the Parent Company with the Securities and Exchange Commission
("SEC"). As a result of the Arthur Andersen report, the SEC commenced an
investigation of the Parent Company on February 10, 1997. The purpose of the
investigation has been to determine whether the Parent Company and persons
associated with the Parent Company violated the federal securities laws
administered by the SEC. The Registrant does not believe that the focus of the
SEC's investigation is upon the Registrant or CCC.

     Current management of the Parent Company has been in discussions with the
staff of the SEC with a view to settling the investigation. The Parent Company
is hopeful of reaching a settlement of the investigation by the end of 1999.

ITEM 3. DEFAULTS UPON SENIOR SECURITIES

     See Item 5. Other Information.

ITEM 5. OTHER INFORMATION

     In 1993, the Parent Company negotiated a credit facility with several banks
for the use by the Parent Company and its subsidiaries, including CCC. At
December 31, 1998, approximately $33,110,000 in principal indebtedness was
outstanding under that credit facility (none of which had been borrowed by the
Registrant). As a party to that credit facility, CCC was jointly and severally
liable for the repayment of all principal and interest owed under the credit
facility. On August 2, 1999, all outstanding amounts under the credit facility
were repaid through the establishment of a new credit facility with two
financial institutions. CCC is not a party to the new loan agreement. The Parent
Company has guaranteed up to $10 million of amounts borrowed under the new
credit facility and, as partial security for this guarantee, the Parent Company
has pledged all of the capital stock held by it in Cronos Holding/Investments
(U.S.), Inc., a Delaware corporation that, in turn, owns all of the outstanding
capital stock of CCC.

     The Registrant is not a borrower under the new credit facility established
by the Parent Company, and neither the containers nor the other assets of the
Registrant have been pledged as collateral under the new credit facility.

                                       13
<PAGE>   14

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

     On August 20, 1999 and August 23, 1999, the Registrant filed a Report on
Form 8-K and a Report on Form 8-K/A, respectively, reporting the change in the
Registrant's independent auditors.

---------------
 * 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

                                          By /s/ PETER J. YOUNGER
                                            ------------------------------------
                                            Peter J. Younger
                                            Chief Financial Officer and
                                             Treasurer of
                                            Cronos Capital Corp. ("CCC")

Date: November 12, 1999


                                       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)
                                       16