<PAGE>

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D. C. 20549

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

                                    FORM 8-K

                                 CURRENT REPORT

                       Pursuant to Section 13 or 15(d) of
                       The Securities Exchange Act of 1934

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

        Date of Report (Date of earliest event reported): October 3, 2005

                          MERRILL LYNCH DEPOSITOR, INC.
                 (ON BEHALF OF PREFERREDPLUS TRUST SERIES CZN-1)
             (Exact name of registrant as specified in its charter)

         DELAWARE                001-16669                    13-3891329
     (State or other           (Commission                (I. R. S. Employer
     jurisdiction  of           File Number)              Identification No.)
      incorporation)

  WORLD FINANCIAL CENTER,                                     10080
    NEW YORK, NEW YORK                                     (Zip Code)
   (Address of principal
    executive offices)
                           --------------------------

       Registrant's telephone number, including area code: (212) 449-1000

                      INFORMATION TO BE INCLUDED IN REPORT

SECTION 1.        REGISTRANT'S BUSINESS AND OPERATIONS

                  Not applicable.

SECTION 2.        FINANCIAL INFORMATION

                  Not applicable.

SECTION 3.        SECURITIES AND TRADING MARKETS

                  Not applicable.

SECTION 4.        MATTERS RELATED TO ACCOUNTANTS AND FINANCIAL STATEMENTS

                  Not applicable.

SECTION 5.        CORPORATE GOVERNANCE AND MANAGEMENT

                  Not applicable.

SECTION 6.        [RESERVED]
<PAGE>

SECTION 7.        REGULATION FD

                  Not applicable.

SECTION 8.        OTHER EVENTS

    ITEM 8.01     OTHER EVENTS

                  99.1     Distribution to holders of the PreferredPLUS Trust
                           Certificates Series CZN-1 on October 3, 2005.

                                    For information with respect to the
                           underlying securities held by PreferredPLUS Trust
                           Series CZN-1, please refer to Citizens Communications
                           Company's (Commission file number 001-11001) periodic
                           reports, including annual reports on Form 10-K,
                           quarterly reports on Form 10-Q and current reports on
                           Form 8-K, and other information on file with the
                           Securities and Exchange Commission (the "SEC"). You
                           can read and copy these reports and other information
                           at the public reference facilities maintained by the
                           SEC at Room 1580, 100 F Street, NE, Washington, D.C.
                           20549. You may obtain copies of this material for a
                           fee by writing to the SEC's Public Reference Section
                           of the SEC at 100 F Street, NE, Washington, D.C.
                           20549. You may obtain information about the operation
                           of the Public Reference Room by calling the SEC at
                           1-800-SEC-0330. You can also access some of this
                           information electronically by means of the SEC's
                           website on the Internet at http://www.sec.gov, which
                           contains reports, proxy and information statements
                           and other information that the underlying securities
                           issuer has filed electronically with the SEC.

                                    Although we have no reason to believe the
                           information concerning the underlying securities or
                           the underlying securities issuer contained in the
                           underlying securities issuer's Exchange Act reports
                           is not reliable, neither the depositor nor the
                           trustee participated in the preparation of such
                           documents or made any due diligence inquiry with
                           respect to the information provided therein. No
                           investigation with respect to the underlying
                           securities issuer (including, without limitation, no
                           investigation as to its financial condition or
                           creditworthiness) or of the underlying securities has
                           been made. You should obtain and evaluate the same
                           information concerning the underlying securities
                           issuer as you would obtain and evaluate if your
                           investment were directly in the underlying securities
                           or in other securities issued by the underlying
                           securities issuer. There can be no assurance that
                           events affecting the underlying securities or the
                           underlying securities issuer have not occurred or
                           have not yet been publicly disclosed which would
                           affect the accuracy or completeness of the publicly
                           available documents described above.

<PAGE>

SECTION 9.        FINANCIAL STATEMENTS AND EXHIBITS

    ITEM 9.01     FINANCIAL STATEMENTS AND EXHIBITS

                  (a) Financial statements of business acquired.

                      Not Applicable.

                  (b) Pro forma financial information.

                      Not Applicable.

                  (c) Exhibits.

                      99.1      Trustee's report in respect of
                                the October 3, 2005 distribution to holders
                                of the PreferredPLUS Trust Certificates
                                Series CZN-1.


<PAGE>



                                   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, hereunto duly authorized.


                                        MERRILL LYNCH DEPOSITOR, INC.

         Date: October 12, 2005         By:    /s/ Zvi Gillon
                                               --------------------------
                                        Name:  Zvi Gillon
                                        Title: Vice President



<PAGE>


                                            EXHIBIT INDEX


             99.1          Trustee's report in respect of the October 3,
                           2005 distribution to holders of the PreferredPLUS
                           Trust Certificates Series CZN-1.
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{"company-data": {"conformed-name": "MERRILL LYNCH DEPOSITOR INC PREFERREDPLUS TRUST SER CZN 1", "cik": "0001157987", "assigned-sic": "6189", "irs-number": "000000000", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "001-16669", "film-number": "051134477"}, "business-address": {"street1": "WORLD FINANCIAL CENTER", "street2": "NORTH TOWER", "city": "NEW YORK", "state": "NY", "zip": "10281"}, "mail-address": {"street1": "WORLD FINANCIAL CENTER", "street2": "NORTH TOWER", "city": "NEW YORK", "state": "NY", "zip": "10281"}}
SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D. C. 20549

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

                                    FORM 8-K

                                 CURRENT REPORT

                       Pursuant to Section 13 or 15(d) of
                       The Securities Exchange Act of 1934

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

        Date of Report (Date of earliest event reported): October 3, 2005

                          MERRILL LYNCH DEPOSITOR, INC.
                 (ON BEHALF OF PREFERREDPLUS TRUST SERIES CZN-1)
             (Exact name of registrant as specified in its charter)

         DELAWARE                001-16669                    13-3891329
     (State or other           (Commission                (I. R. S. Employer
     jurisdiction  of           File Number)              Identification No.)
      incorporation)

  WORLD FINANCIAL CENTER,                                     10080
    NEW YORK, NEW YORK                                     (Zip Code)
   (Address of principal
    executive offices)
                           --------------------------

       Registrant's telephone number, including area code: (212) 449-1000

                      INFORMATION TO BE INCLUDED IN REPORT

SECTION 1.        REGISTRANT'S BUSINESS AND OPERATIONS

                  Not applicable.

SECTION 2.        FINANCIAL INFORMATION

                  Not applicable.

SECTION 3.        SECURITIES AND TRADING MARKETS

                  Not applicable.

SECTION 4.        MATTERS RELATED TO ACCOUNTANTS AND FINANCIAL STATEMENTS

                  Not applicable.

SECTION 5.        CORPORATE GOVERNANCE AND MANAGEMENT

                  Not applicable.

SECTION 6.        [RESERVED]
SECTION 7.        REGULATION FD

                  Not applicable.

SECTION 8.        OTHER EVENTS

    ITEM 8.01     OTHER EVENTS

                  99.1     Distribution to holders of the PreferredPLUS Trust
                           Certificates Series CZN-1 on October 3, 2005.

                                    For information with respect to the
                           underlying securities held by PreferredPLUS Trust
                           Series CZN-1, please refer to Citizens Communications
                           Company's (Commission file number 001-11001) periodic
                           reports, including annual reports on Form 10-K,
                           quarterly reports on Form 10-Q and current reports on
                           Form 8-K, and other information on file with the
                           Securities and Exchange Commission (the "SEC"). You
                           can read and copy these reports and other information
                           at the public reference facilities maintained by the
                           SEC at Room 1580, 100 F Street, NE, Washington, D.C.
                           20549. You may obtain copies of this material for a
                           fee by writing to the SEC's Public Reference Section
                           of the SEC at 100 F Street, NE, Washington, D.C.
                           20549. You may obtain information about the operation
                           of the Public Reference Room by calling the SEC at
                           1-800-SEC-0330. You can also access some of this
                           information electronically by means of the SEC's
                           website on the Internet at http://www.sec.gov, which
                           contains reports, proxy and information statements
                           and other information that the underlying securities
                           issuer has filed electronically with the SEC.

                                    Although we have no reason to believe the
                           information concerning the underlying securities or
                           the underlying securities issuer contained in the
                           underlying securities issuer's Exchange Act reports
                           is not reliable, neither the depositor nor the
                           trustee participated in the preparation of such
                           documents or made any due diligence inquiry with
                           respect to the information provided therein. No
                           investigation with respect to the underlying
                           securities issuer (including, without limitation, no
                           investigation as to its financial condition or
                           creditworthiness) or of the underlying securities has
                           been made. You should obtain and evaluate the same
                           information concerning the underlying securities
                           issuer as you would obtain and evaluate if your
                           investment were directly in the underlying securities
                           or in other securities issued by the underlying
                           securities issuer. There can be no assurance that
                           events affecting the underlying securities or the
                           underlying securities issuer have not occurred or
                           have not yet been publicly disclosed which would
                           affect the accuracy or completeness of the publicly
                           available documents described above.
SECTION 9.        FINANCIAL STATEMENTS AND EXHIBITS

    ITEM 9.01     FINANCIAL STATEMENTS AND EXHIBITS

                  (a) Financial statements of business acquired.

                      Not Applicable.

                  (b) Pro forma financial information.

                      Not Applicable.

                  (c) Exhibits.

                      99.1      Trustee's report in respect of
                                the October 3, 2005 distribution to holders
                                of the PreferredPLUS Trust Certificates
                                Series CZN-1.
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, hereunto duly authorized.

                                        MERRILL LYNCH DEPOSITOR, INC.

         Date: October 12, 2005         By:    /s/ Zvi Gillon
                                               --------------------------
                                        Name:  Zvi Gillon
                                        Title: Vice President
EXHIBIT INDEX

             99.1          Trustee's report in respect of the October 3,
                           2005 distribution to holders of the PreferredPLUS
                           Trust Certificates Series CZN-1.