Isabella Bank (ISBA) 8-K ISBA Announces Fourth Quarter 2012 Dividend

Exhibit 99.1

ISBA Announces Fourth Quarter 2012 Dividend

Mt. Pleasant, Michigan, November 30, 2012—Richard Barz, Chief Executive Officer of Isabella Bank Corporation (ISBA), announced today that the Corporation’s Board of Directors, at its regular meeting held on November 28, 2012, declared a fourth quarter cash dividend of $0.20 per share. The dividend will be payable on December 28, 2012 to shareholders of record as of December 26, 2012. This cash dividend represents a 5.26% increase compared to the fourth quarter dividend of 2011. The closing stock price for ISBA on November 28, 2012 was $22.85.

For more information about Isabella Bank Corporation, visit the Investors link atwww.isabellabank.com. Isabella Bank Corporation common stock is quoted on the OTCQB tier of the OTC Markets Group, Inc.’s electronic quotation system (www.otcmarkets.com) under the symbol “ISBA.”