EXHIBIT 23.1 CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM Board of Directors IBT Bancorp, Inc. We consent to the incorporation by reference in the proxy statement-prospectus included in this Registration Statement on Form S-4 of IBT Bancorp, Inc. of our report dated March 3, 2006, which appears on pages 35-36 on Form 10-K for the year ended December 31, 2005, and to the reference to our firm under the caption "Experts" in the proxy statement-prospectus. /s/ REHMANN ROBSON --------------------------------------- Saginaw, Michigan August 18, 2006 Exhibit 23.1-1