To prevent those negative consequences, the group proposed several ways to pump up to $2.4 billion more into city and CPS coffers each year. Among them: closing state corporate tax loopholes; replacing the state's flat income tax with a graduated tax that would require people making more money to pay more; and expanding the sales tax to include services while lowering the overall rate. That sales-tax approach is similar to the so-called "Rahm" tax that Emanuel proposed during his 2011 campaign but that never went anywhere in the face of withering criticism.