UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

~~FORM~~ Form 8-K

CURRENT REPORT

~~PURSUANT TO~~Pursuant ~~SECTION~~to Section 13 ORor 15(d) OFof ~~THE~~the

~~SECURITIES~~Securities ~~EXCHANGE~~Exchange ~~ACT~~Act OFof 1934

Date of Report (Date of earliest event ~~reported)~~

27Reported): June 9, 2005 Credit Suisse First Boston Mortgage Securities Corp. Home Equity Pass-~~Dec~~Through Certificates Series 2004-04AA1

Credit Suisse First Boston Mortgage Securities Corp., Home Equity Pass-Through Certificates Series 2004-AA1

CREDIT SUISSE FIRST BOSTON MORTGAGE SECURITIES CORP.
(Exact name of registrant as specified in its charter)
Delaware	333-120966	13-3320910
(State or Other Jurisdiction of Incorporation)	(Commission File Number)	(I.R.S. Employer Identification No.)

Eleven Madison Avenue New York, New York 10010
(Address of Principal Executive Offices) (Zip Code)

Registrant’s telephone number, including area code (212) 325-2000

~~Credit~~Check ~~Suisse~~the ~~First~~appropriate ~~Boston~~box ~~Mortgage~~below ~~Securities~~if ~~Corp.~~ the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

[ ] Written communications pursuant to Rule 425 under the Securities Act (~~Exact Name~~17 ofCFR ~~Registrant~~230.425) as[ ~~Specified~~] inSoliciting ~~its~~material ~~Charter~~pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) [ ] Pre-commencement communications pursuant to Rule 14d-2(d) under the Exchange Act (17 CFR 240.14d-2(b)) [ ] Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Delaware	333-107055-40	13-3320910
(State or Other Jurisdiction Of Incorporation)	(Commission File Number)	(I.R.S. Employer Identification No.)

Item 8.01. Other Events.

11This ~~Madison~~Current ~~Avenue~~Report ~~New~~on ~~York~~Form 8-K is being filed to file a copy of the Pooling and Servicing Agreement dated as of October 1, ~~New~~2004, ~~York~~among Credit Suisse First Boston Mortgage Securities Corp., as depositor, DLJ Mortgage Capital, Inc., as seller, Wells Fargo Bank, N.A., as a servicer (~~Address~~in ofsuch ~~PrincipalExecutive~~capacity ~~Offices~~“WFBNA”), ~~10010~~as back-up servicer and as master servicer and Ocwen Federal Bank FSB, as a servicer (~~Zip~~“Ocwen” ~~Code~~and together with WFBNA, the “Servicers”), The Murrayhill Company, as credit risk manager and U.S. Bank National Association, as trustee (the “Pooling and Servicing Agreement”), in connection with the issuance by Credit Suisse First Boston Mortgage Securities Corp. of Home Equity Pass-Through Certificates Series 2004-AA1.

~~Registrant's~~Item ~~telephone number, including area code: (212) 325-2000~~9.01.

~~Check~~Financial ~~the~~Statements, ~~appropriate~~Pro ~~box~~Forma ~~below~~Financial ifInformation ~~the~~and ~~Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A~~Exhibits.~~2. below):~~

~~[ ] Written communications pursuant to Rule 425 under the Securities Act~~ (~~17 CFR 230.425~~q)

~~[ ]~~Not ~~Soliciting material pursuant to Rule 14a-12(b) under the Exchange Act (17 CFR 240~~applicable.~~14a-12(b))~~

~~[ ] Pre-commencement communications pursuant to Rule 14d-2~~(br) ~~under the Exchange Act (17 CFR 240.14d-2(b))~~

~~[ ]~~Not ~~Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240~~applicable.~~13e-4(c))~~

~~Item 8.01 Other Events.~~(s)

On 27-Dec-04 a scheduled distribution was made from the Trust to holders of the Certificates. The Trustee has caused to be filed with the Commission, the Monthly Report dated 27-Dec-04. The Monthly Report is filed pursuant to and in accordance with (1) numerous no-action letters (2) current Commission policy in the area.Exhibits:

~~Item 9~~4.~~01 Financial~~1 ~~Statements~~Pooling and ~~Exhibits.~~Servicing Agreement

Exhibit No. 99.1

Monthly Distribution Report dated: 27-Dec-04

SIGNATURES

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

~~By: U.S.~~CREDIT ~~Bank~~SUISSE ~~National~~FIRST ~~Association,~~BOSTON ~~as Trustee for:~~ MORTGAGE SECURITIES CORP.

~~Credit~~By: ~~Suisse~~/s/ ~~First~~John ~~Boston Mortgage Securities Corp~~P., Graham

~~Home~~ Name: ~~Equity~~John ~~Pass-Through~~P. ~~Certificates~~Graham

~~Series~~ Title: ~~2004-AA1~~Vice President

ByDated: June 9, 2005

~~/s/ Sheryl~~EXHIBIT ~~Christopherson~~4.1

~~Name:~~[See Tab 3]

Sheryl Christopherson

Title:

Vice President

Dated: 03-Jan-05

Index to Exhibits

Exhibit No. 99.1

Monthly Distribution Report dated: 27-Dec-04

Filing Compare · CSFB Home Equity Pass-Through 2004-AA1