Synopsis As Introduced Amends the Illinois Municipal Code. Creates the Municipal Gas Use Tax Law. Provides that beginning January 1, 2020, a municipality may impose a self-assessing purchaser tax rate of the lower of 2.4 cents per therm or 5% of the purchase price for the privilege of using in the municipality gas obtained in a purchase of out-of-state gas. Provides that, in the alternative, a purchaser may elect for a tax of 2.4 cents per therm that a delivering supplier maintaining a place of business in the State collects from the purchaser. Provides for registration requirements for self-assessing purchasers and delivering suppliers. Includes procedures for self-assessing purchasers and delivering suppliers to submit returns and to remit the tax to the Department of Revenue. Effective January 1, 2020.