N.M. Code R. § 20.2.79.114
The baseline for determining credit for emission offsets shall be the most stringent emissions limitation pursuant to a New Mexico air quality regulation or federally enforceable permit which is applicable and in effect at the time the application to construct is filed. If neither a state air quality regulation nor a federally enforceable permit contains an emissions limitation for the source, the baseline shall be the actual emissions of the source from which offset credit is obtained. Where a source is subject to an emission standard established in a New Source Performance Standard (NSPS) or a National Emission Standard for Hazardous Air Pollutants (NESHAPS) and a different State Implementation Plan or permit limitation, including any emission limitation used in demonstrating reasonable further progress, the more stringent emission standard shall be used as the baseline for determining credit for emission offsets.
N.M. Code R. § 20.2.79.114