The Illinois Commerce Commission authorized $71.6 million in additional revenue for Ameren Illinois Company’s electric service, resulting in a $4 increase in monthly residential bills, according to a Nov. 1 press release. The commission approved $31.7 million rate increase for the company’s gas delivery service, raising monthly bills by about $3.50. The gas rates take effect this month, and the electric rates in January 2019. Both the rates reflect changes from the federal tax law that slashed the corporate income tax rate to 21 percent from 35 percent. Ameren Illinois is a subsidiary of Ameren Corporation.