Interim Approval Information

An Interim Approval allows the applicant, under certain limited circumstances and at their own risk, to commence construction of a new emissions unit at an existing source or modification of an emissions unit at an existing source while the permit application is being reviewed. Interim approvals are subject to the requirements of 326 IAC 2-13-1.

Detailed information preparing an Interim Petition, and the applicable forms, are provided below. For additional information, please also refer to Frequently Asked Questions & Answers about Interim Approvals.


The interim petition is applicable to proposed modification/revision to an existing source operating under valid operating permit(s) and located in an attainment area.

Non-eligible Projects

Modifications/revisions ineligible for the interim petition program include:

  • Construction of a new major PSD facility or major PSD modification to an existing source, or
  • Construction in a nonattainment areas that would emit those pollutants for which the nonattainment designation is based, or
  • Construction of a totally new plant, or
  • Any modification that is subject to 326 IAC 2-4.1 (New Source Toxics Control).


Questions or Concerns

If you have questions or would like to schedule a pre-application meeting, contact the Office of Air Quality. If you have inquiries that are confidential in nature, want to discuss permitting options for various scenarios, need advice that is technical in nature, or need help choosing and filling out application forms, contact IDEM's Compliance and Technical Assistance Program for free and confidential assistance.