Amends the Public Utilities Act. Provides that gas main and gas service extension policies shall be based on the principle that the full incremental cost associated with development and growth of the gas main to the customer's property shall be borne by the customers that cause those incremental costs. Provides that no later than 60 days after the effective date of this amendatory Act, the Illinois Commerce Commission shall initiate a docketed rulemaking reviewing each gas public utility tariff that provides for gas main and gas service extensions without additional charge to new customers in excess of the default extensions without charge as specified in administrative rule. The focus of the rulemaking shall be to modify each gas utility's gas main and gas service extension tariff to align with these provisions.