This action establishes state implementation plan (SIP) submittal requirements (including elements required to be submitted, submittal deadlines, and where applicable, implementation deadlines) for nonattainment areas reclassified under the 2015 ozone National Ambient Air Quality Standards (NAAQS). This action is necessary in anticipation of separate determinations of whether certain nonattainment areas for the 2015 ozone NAAQS attained by the attainment date, based on the areas’ design values as of the attainment date, which will be addressed in separate actions. Specifically, the action proposes to establish SIP submittal and implementation deadlines for 2015 ozone NAAQS Moderate nonattainment areas that are reclassified for failing to attain the standard by the attainment date. All Moderate nonattainment areas must attain the ozone standard within 6 years of the effective date of the designation, or by August 3, 2024, unless an area is granted a 1-year attainment date extension. If a Moderate area fails to attain the standard by the attainment date, the area will be reclassified to the classification applicable to the area’s design value by operation law. In this notice, the U.S. Environmental Protection Agency proposes to establish SIP submittal deadlines and related implementation requirements for Moderate nonattainment areas that are reclassified.