8-K

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 1, 2007

Southern Michigan Bancorp, Inc.
(Exact Name of Registrant as
Specified in its Charter)

Michigan
(State or Other Jurisdiction
of Incorporation) 000-49772
(Commission
File Number) 38-2407501
(IRS Employer
Identification No.)

51 West Pearl Street
P.O. Box 309
Coldwater, Michigan
(Address of Principal Executive Offices)
49036-1995
(Zip Code)

Registrant's telephone number, including area code:  (517) 279-5500

Check the appropriate box below if the 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.2. below):

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

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

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

o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 7.01. Regulation FD Disclosure

          On December 3, 2007, Southern Michigan Bancorp, Inc. ("Southern") issued a press release announcing that Southern has completed its previously announced acquisition of FNB Financial Corporation.

          Southern intends to file an additional report on Form 8-K within four business days of this report that will provide additional details about the acquisition.

          A copy of the press release is attached to this report as Exhibit 99.1 and is here incorporated by reference. This report and the Exhibit are furnished to, and not filed with, the Commission.

Item 9.01.	Financial Statements and Exhibits.
	(d)	Exhibits:
	99.1	Press Release dated December 3, 2007. This Exhibit is furnished to, and not filed with, the Commission.

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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.

Dated:  December 1, 2007	SOUTHERN MICHIGAN BANCORP, INC. (Registrant)
	By:	/s/ Danice L. Chartrand
		Danice L. Chartrand Senior Vice President, Chief Financial Officer, Secretary and Treasurer

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EXHIBIT INDEX

Exhibit Number	Document
99.1	Press Release, dated December 3, 2007. This Exhibit is furnished to, and not filed with, the Commission.

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EX-99.1

EXHIBIT 99.1

SOUTHERN MICHIGAN BANCORP, INC.
51 West Pearl Street
Coldwater, MI 49036

FOR IMMEDIATE RELEASE
CONTACT:  John H. Castle, CEO
(517) 279-5500

Southern Michigan Bancorp, Inc. Announces Completion of FNB Financial Corporation Acquisition

Coldwater, Michigan, December 3, 2007: Southern Michigan Bancorp, Inc. ("Southern") today announced that it has completed its acquisition of FNB Financial Corporation ("FNB"), a bank holding company, and its wholly-owned subsidiary bank, The First National Bank of Three Rivers.

John H. Castle, Chairman & Chief Executive Officer of Southern, said, "We are pleased to have completed this acquisition. Although The First National Bank of Three Rivers and Southern Michigan Bank & Trust will continue to serve their respective clients as individually-chartered banks, we believe our combined corporate resources will strengthen us to be more competitive and responsive to businesses and individuals in the markets we serve." Castle continued, "we want to welcome all of FNB's shareholders, customers, and employees to the Southern family. We look forward to the smooth integration of our companies and hope to complete the core processing system conversion early in the second quarter of 2008."

Based on Southern's closing stock price on November 30, 2007, the transaction is valued at $24.7 million. Southern is now a two bank holding company headquartered in Coldwater, Michigan with assets of approximately $470 million and 19 branches within Branch, Calhoun, Cass, Hillsdale and St. Joe Counties.