Washington Bancorp (WBIO) is an Iowa corporation which was organized in October 1995 by Washington Federal Savings Bank for the purpose of becoming a savings and loan holding company. Washington Federal was a federally chartered savings bank, headquartered in Washington, Iowa. Originally chartered as a savings and loan institution in 1934, Washington Federal converted to a federal savings bank in 1994.

In March, 1996, Washington Federal converted to the stock form of organization through the sale and issuance of its common stock to the company. On June 24, 1997, WBIO entered into a merger agreement to acquire the Rubio Savings Bank of Brighton, Iowa. Rubio Savings Bank was then held as a separate subsidiary of Washington Bancorp. In January 1998, Washington Bancorp became a bank holding company upon the completion of its acquisition of Rubio Savings Bank. In December 1998, Washington Federal opened a branch office, Wellman Federal Savings, in Wellman, Iowa. In September 2000, Washington Federal opened a second branch, Richland Federal Savings, in Richland, Iowa.

On April 15, 2003, Washington Bancorp merged Washington Federal with Rubio Savings Bank to form Federation Bank. The original 1906 state charter from Rubio Savings Bank was retained, and the main office is located in Washington, while the data processing system is in Brighton.  The executive office of the company is located at 102 East Main Street, Washington, Iowa, 52353, telephone (319) 653-7256.