The U.S Environmental Protection Agency (EPA) is finalizing amendments to the electronic reporting requirements for the National Emission Standards for Hazardous Air Pollutants: Coal- and Oil-Fired Electric Utility Steam Generating Units (also known as the Mercury and Air Toxics Standards (MATS)). This action revises and streamlines the electronic data reporting requirements of MATS, increases data transparency by requiring use of one electronic reporting system instead of two separate systems, and provides enhanced access to MATS data. No new monitoring requirements are imposed by this final action; instead, this action reduces reporting burden, increases MATS data flow and usage, makes it easier for inspectors and auditors to assess compliance, and encourages wider use of continuous emissions monitoring systems (CEMS) for MATS compliance. In addition, this final action extends the current deadline for alternative electronic data submission via portable document format (PDF) files through December 31, 2023.