The Environmental Protection Agency EPA is proposing deadlines for submission of state implementation plan SIP revisions and implementation of the relevant control requirements that will apply for nonattainment areas reclassified as Moderate Serious and Severe under the current and any future ozone National Ambient Air Quality Standards NAAQS as a result of either failing to attain the standard by the applicable classification attainment date or the EPA granting a voluntary reclassification request. This proposal articulates the implementation requirements and timeframes that will apply for all such areas once reclassified. The EPA is also proposing regulatory revisions to codify its existing interpretation that following reclassification a state is no longer required to submit SIP revisions addressing certain but not all requirements related to the prior classification level for an ozone nonattainment area. In addition the EPA is articulating in this document how the proposed default deadlines and codification of applicable requirements following reclassification would apply specifically to any nonattainment areas that are reclassified as Serious under the 2015 ozone NAAQS.