<PAGE>

================================================================================

                                 UNITED STATES
                       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): December 28, 2006

                        Alternative Loan Trust 2006-45T1
                        --------------------------------
                       (Exact name of the issuing entity)
          Commission File Number of the issuing entity: 333-131630-[o]

                                  CWALT, Inc.
                                  -----------
                (Exact name of the depositor as specified in its
                     charter) Commission File Number of the
                             depositor: 333-131630

                          Countrywide Home Loans Inc.
                          ---------------------------
            (Exact name of the sponsor as specified in its charter)


               Delaware                                87-0698307
               --------                                ----------
     (State or Other Jurisdiction                   (I.R.S. Employer
  of Incorporation of the depositor)      Identification No. of the depositor)

4500 Park Granada
Calabasas, California                                    91302
---------------------                                  ----------
(Address of Principal                                  (Zip Code)
 Executive Offices of the depositor)

The depositor's telephone number, including area code (818) 225-3000
                                                      --------------

================================================================================

Check the appropriate box below if the Form 8-K filing is intended to
simultaneously satisfy the filing obligation of the registrant under any
following provisions:

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

[ ]      Soliciting material pursuant to Rule 14a-12(b) under the Exchange Act
         (17 CFR 240.14a- 12(b))

[ ]      Pre-commencement communications pursuant to Rule 14d-2(b) 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))

<PAGE>

Section 7         Regulation FD
---------

Item 7.01         Regulation FD Disclosure.
                  ------------------------

         On December 28, 2006, CWALT, Inc. (the "Depositor") created the
Alternative Loan Trust 2006-45T1 (the "Issuing Entity") pursuant to a Pooling
and Servicing Agreement, dated as of December 1, 2006 (the "Pooling and
Servicing Agreement"), among the Depositor, Countrywide Home Loans, Inc., as a
seller, Park Grananda LLC, as a seller, Park Monaco Inc., as a seller, Park
Sienna LLC, as a seller, Countrywide Home Loans Servicing LP, as master
servicer, and The Bank of New York, as trustee. Capitalized terms used but not
defined herein shall have the respective meanings assigned to them in the
Pooling and Servicing Agreement.

         On December 28, 2006, the Depositor transferred the Mortgage Loans to
the Issuing Entity. The loan level data tape attached hereto as Exhibit 99.1
describes characteristics of each Mortgage Loan as of its Cut-off Date.

Item 9.01.  Financial Statements and Exhibits.
----------  ----------------------------------

(a)      Not applicable.

(b)      Not applicable.

(c)      Exhibits:

         Exhibit No.       Description
         -----------       -----------

         99.1              Characteristics of the Mortgage Loans


<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.

                                             CWALT, INC.




                                             By: /s/ Darren Bigby
                                                 -------------------------------
                                                 Name:  Darren Bigby
                                                 Title: Vice President


Dated:  January 11, 2007


<PAGE>

                                 Exhibit Index
                                 -------------


Exhibit No.       Description
-----------       -----------

99.1              Characteristics of the Mortgage Loans
[{"type": "8-K", "sequence": "1", "filename": "b416640_8k.txt", "description": "FORM 8-K", "secsgml_size_bytes": 4862}]
{"company-data": {"conformed-name": "Alternative Loan Trust 2006-45T1", "cik": "0001382636", "assigned-sic": "6189", "irs-number": "000000000", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "333-131630-77", "film-number": "07525211"}, "business-address": {"street1": "4500 PARK GRANADA", "city": "CALABASAS", "state": "CA", "zip": "91302", "phone": "818-332-5300"}, "mail-address": {"street1": "4500 PARK GRANADA", "city": "CALABASAS", "state": "CA", "zip": "91302"}}
================================================================================

                                 UNITED STATES
                       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): December 28, 2006

                        Alternative Loan Trust 2006-45T1
                        --------------------------------
                       (Exact name of the issuing entity)
          Commission File Number of the issuing entity: 333-131630-[o]

                                  CWALT, Inc.
                                  -----------
                (Exact name of the depositor as specified in its
                     charter) Commission File Number of the
                             depositor: 333-131630

                          Countrywide Home Loans Inc.
                          ---------------------------
            (Exact name of the sponsor as specified in its charter)

               Delaware                                87-0698307
               --------                                ----------
     (State or Other Jurisdiction                   (I.R.S. Employer
  of Incorporation of the depositor)      Identification No. of the depositor)

4500 Park Granada
Calabasas, California                                    91302
---------------------                                  ----------
(Address of Principal                                  (Zip Code)
 Executive Offices of the depositor)

The depositor's telephone number, including area code (818) 225-3000
                                                      --------------

================================================================================

Check the appropriate box below if the Form 8-K filing is intended to
simultaneously satisfy the filing obligation of the registrant under any
following provisions:

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

[ ]      Soliciting material pursuant to Rule 14a-12(b) under the Exchange Act
         (17 CFR 240.14a- 12(b))

[ ]      Pre-commencement communications pursuant to Rule 14d-2(b) 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))
Section 7         Regulation FD
---------

Item 7.01         Regulation FD Disclosure.
                  ------------------------

         On December 28, 2006, CWALT, Inc. (the "Depositor") created the
Alternative Loan Trust 2006-45T1 (the "Issuing Entity") pursuant to a Pooling
and Servicing Agreement, dated as of December 1, 2006 (the "Pooling and
Servicing Agreement"), among the Depositor, Countrywide Home Loans, Inc., as a
seller, Park Grananda LLC, as a seller, Park Monaco Inc., as a seller, Park
Sienna LLC, as a seller, Countrywide Home Loans Servicing LP, as master
servicer, and The Bank of New York, as trustee. Capitalized terms used but not
defined herein shall have the respective meanings assigned to them in the
Pooling and Servicing Agreement.

         On December 28, 2006, the Depositor transferred the Mortgage Loans to
the Issuing Entity. The loan level data tape attached hereto as Exhibit 99.1
describes characteristics of each Mortgage Loan as of its Cut-off Date.

Item 9.01.  Financial Statements and Exhibits.
----------  ----------------------------------

(a)      Not applicable.

(b)      Not applicable.

(c)      Exhibits:

         Exhibit No.       Description
         -----------       -----------

         99.1              Characteristics of the Mortgage Loans
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.

                                             CWALT, INC.

                                             By: /s/ Darren Bigby
                                                 -------------------------------
                                                 Name:  Darren Bigby
                                                 Title: Vice President

Dated:  January 11, 2007
Exhibit Index
                                 -------------

Exhibit No.       Description
-----------       -----------

99.1              Characteristics of the Mortgage Loans