UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K [X] Annual report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the period from April 1, 2002 (Commencement of Operations) to December 31, 2002 [ ] 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 333-77054-12 CREDIT SUISSE FIRST BOSTON MORTGAGE SECURITIES CORP. (Exact name of registrant as specified in its charter) Delaware 13-3320910 (State or other jurisdiction of I.R.S. Employer incorporation or organization) Identification No.) 11 Madison Ave. New York, New York 10010 (Address of Principal Executive Offices) (Zip Code) Registrant's telephone number, including area code :(212)325-2000 CREDIT SUISSE FIRST BOSTON MORTGAGE SECURITIES CORP. CSFB Mortgage-Backed Pass-Through Certificates, Series 2002-S12 (Title of each class of securities covered by this Form) Securities registered pursuant to Section 12(b) of the Act: None Securities registered pursuant to Section 12(g) of the Act: None 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 [ ] Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant's knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. [X] Documents incorporated by reference: None CREDIT SUISSE FIRST BOSTON MORTGAGE SECURITIES CORP. CSFB Mortgage-Backed Pass-Through Certificates, Series 2002-S12 - ----------------------------------------------------------------------- PART I Item 1. Business Omitted. Item 2. Properties Omitted. Item 3. Legal Proceedings The Registrant is not aware of any material legal proceeding with respect to, the Company, the Master Servicer, the Servicers, the Trust Administrator or the Trustee, in each case if applicable, as related to the Trust. Item 4. Submission of Matters to a Vote of Security Holders No matter was submitted to a vote or consent of Holders of the Offered Certificates during the fiscal year covered by this report. PART II Item 5. Market for Registrant's Common Equity and Related Stockholder Matters The Trust does not issue stock. There is currently no established secondary market for the Certificates. As of December 31, 2002, the number of holders of each Class of Offered Certificates was 38. Item 6. Selected Financial Data Omitted. Item 7. Management's Discussion and Analysis of Financial condition and Results of Operations Omitted. Item 8. Financial Statements and Supplementary Data Omitted. Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure There was no change of accountants or disagreement with accountants on any matter of accounting principles or practices or financial disclosure. -2- PART III Item 10. Directors and Executive Officers of the Registrant Omitted. Item 11. Executive Compensation Omitted. Item 12. Security Ownership of Certain Beneficial Owners and Management Omitted. Item 13. Certain Relationships and Related Transactions No reportable transactions have occurred. PART IV Item 14. Exhibits, Financial Statement Schedules and Reports on Form 8-K (a) The following documents are filed as part of this report: (1) Financial Statements: Omitted. (2) Financial Statement Schedules: Omitted. (3) Exhibits: Annual Servicers' Statement of Compliance, filed as Exhibit 99.1 hereto. Annual Statement of Independent Accountants Report for the Servicers, filed as Exhibit 99.2 hereto. (b) Reports on Form 8-K: The following Current Reports on Form 8-K were filed by the Registrant during the last quarter of 2002. Current Reports on Form 8-K, dated October 25, 2002, November 25, 2002, and December 26, 2002, were filed for the purpose of filing the Monthly Statement sent to the Holders of the Offered Certificates for payments made on the same dates. The items reported in such Current Report were Item 5 (Other Events). (c) Exhibits to this report are listed in Item (14)(a)(3) above. -3- Annual report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the fiscal year ended December 31, 2002 CREDIT SUISSE FIRST BOSTON MORTGAGE SECURITIES CORP. CSFB MORTGAGE PASS-THROUGH CERTIFICATES, SERIES 2002-S12 - -------------------------------------------------------- SIGNATURE Pursuant to the requirements of Section 13 or 15(d) 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. CREDIT SUISSE FIRST BOSTON MORTGAGE SECURITIES CORP. Date: March 31, 2003 By: /s/ Matt Ruppel -------------------------------------- Name: Matt Ruppel Title: Vice President -4- CERTIFICATION Re: Credit Suisse First Boston Mortgage Securities Corp., CSFB Trust Series 2002-S12 CSFB Mortgage Pass-Through Certificates, Series 2002-S12 I, Matt Ruppel, certify that: 1. I have reviewed this annual report on Form 10-K, and all reports on Form 8-K containing distribution and servicing reports filed in respect of periods included in the year covered by this annual report, of CSFB Trust Series 2002-S12 (the "Trust"); 2. Based on my knowledge, the information in these reports, taken as a whole, does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading as of the last day of the period covered by this annual report; 3. Based on my knowledge, the distribution information required to be prepared by the Trustee based upon the servicing information required to be provided by each Servicer under the Pooling and Servicing Agreement is included in these reports; 4. Based on my knowledge and upon the annual compliance statements included in the report and required to be delivered to the Trustee in accordance with the terms of the Pooling and Servicing Agreement and based upon the review required under the Pooling and Servicing Agreement, and except as disclosed in the report, each Servicer has fulfilled its obligations under the Pooling and Servicing Agreement; and 5. The reports disclose all significant deficiencies relating to each Servicer's compliance with the minimum servicing standards based, in each case, upon the report provided by an independent public accountant, after conducting a review in compliance with the Uniform Single Attestation Program for Mortgage Bankers or similar standard as set forth in the Pooling and Servicing Agreement, that is included in these reports. Capitalized terms used but not defined herein have the meanings ascribed to them in the Pooling and Servicing Agreement, dated April 1, 2002 (the "Pooling and Servicing Agreement"), among Credit Suisse First Boston Mortgage Securities Corp., as depositor (the "Depositor"), DLJ Mortgage Capital, Inc., as seller (the "Seller"), Wilshire Credit Corporation, as a servicer (in such capacity, a "Servicer"), Ocwen Federal Bank FSB, as a servicer (in such capacity, a "Servicer") and JPMorgan Chase Bank, as trustee (the "Trustee"). Dated: March 31, 2003 By: /s/ Matt Ruppel -------------------------------------- Name: Matt Ruppel Title: Vice President -5- <page> SUPPLEMENTAL INFORMATION TO BE FURNISHED WITH REPORTS FILED PURSUANT TO SECTION 15(D) OF THE ACT BY REGISTRANTS WHICH HAVE NOT REGISTERED SECURITIES PURSUANT TO SECTION 12 OF THE ACT. The registrant has not sent an annual report or proxy material to its security holders. The registrant will not be sending an annual report or proxy material to its security holders subsequent to the filing of this form. -6- EXHIBIT INDEX Exhibit Description 99.1 Servicers' Annual Statement of Compliance 99.2 Servicers' Annual Independent Accountant's Report -7- EXHIBIT 99.1 - Servicers' Annual Statement of Compliance To be supplied upon receipt by the Trustee -8- EXHIBIT 99.2 - Servicers' Annual Independent Accountant's Report To be supplied upon receipt by the Trustee -9-