On December 1, 2000, the EPA adopted emission guidelines for existing commercial and industrial solid waste incineration (CISWI) units. Sections 111 and 129 of the Clean Air Act (CAA) require States with existing CISWI units subject to the emission guidelines to submit to the EPA plans that implement and enforce the emission guidelines. Indian Tribes may submit, but are not required to submit, Tribal plans to implement and enforce the emission guidelines in Indian country. State plans were due from States with CISWI units subject to the emission guidelines on December 1, 2001. If a State or Tribe with existing CISWI units does not submit an approvable plan, sections 129 and 111 of the CAA require the EPA to develop, implement, and enforce a Federal plan for CISWI units located in that State or Tribal area within 2 years after promulgation of the emission guidelines (December 1, 2002). The EPA proposed a Federal plan for CISWI units on November 25, 2002. This action promulgates a Federal plan to implement emission guidelines for CISWI units located in States and Indian country without effective State or Tribal plans. This Federal plan is an interim action because on the effective date of an approved State or Tribal plan, the Federal plan will no longer apply to CISWI units covered by the State or Tribal plan.