What EPA finalized

EPA’s final rule creates a new NSPS structure (in 40 CFR Part 60, subpart KKKKa) that sets emissions limits for nitrogen oxides (NOx). Under EPA’s framework, it also addresses sulfur dioxide (SO2). The rule is effective January 15, 2026.

EPA also shows a correction dated July 13, 2026 tied to the final rule package. If you are building or updating compliance documentation, use the corrected materials.

Who is covered (and what triggers the new standards)

The standards don’t automatically reach every existing power plant or industrial site. In plain terms, the NSPS applies when a facility has a covered stationary combustion turbine that commenced construction, modification, or reconstruction after December 13, 2024.

The rule also describes an option for some units that were already covered under older subparts to petition to comply using the newer approach.

What changes for NOx: limits depend on the turbine category

EPA sets NOx limits that vary by how the turbine is categorized—based on factors like unit size and operating characteristics. EPA’s fact sheet explains the rule uses size-based subcategories and then distinguishes between units using operating and design thresholds.

EPA says combustion controls are the best system of emission reduction (BSER) for most covered subcategories. For one specific NOx subcategory, EPA’s BSER includes combustion controls plus selective catalytic reduction (SCR).

In practice, this category-based structure means permits and compliance plans may focus on how the project is categorized, what control equipment is proposed (including whether SCR is used), and how performance tests will be documented.

The near-term compliance shift: electronic reporting in 2026–2027

EPA’s rule places major emphasis on electronic submission.

• Beginning March 16, 2026, owners/operators must submit key performance test and CEMS performance evaluation results electronically, within 60 days after the date of completing each performance test or CEMS performance evaluation.
• For semiannual reporting, the rule requires electronic submissions via CEDRI by the 30th day following the end of each 6-month period.
• Semiannual reporting begins January 15, 2027, with timing also tied to when report templates for the subpart are available on EPA’s CEDRI website.

The systems involved include CEDRI for compliance reporting submissions and the Electronic Reporting Tool (ERT) for generating electronic files connected to performance testing documentation.

Reader impact: permits, documentation, and uneven timing by project

For communities near covered facilities and for energy consumers, the rule matters most through what it changes for new, modified, or reconstructed turbine projects: the equipment decisions that support NOx compliance and the administrative workflow for compliance evidence.

Because the standards hinge on whether construction/modification/reconstruction occurred after December 13, 2024, effects will be uneven across regions and plants—showing up primarily where projects are moving forward under the new trigger and where air agencies update permit conditions and reporting schedules accordingly.

Sources

• EPA NSPS hub page: Stationary Gas and Combustion Turbines (Final Rule)
• Federal Register (EPA final NSPS): “New Source Performance Standards Review for Stationary Combustion Turbines and Stationary Gas Turbines” (Jan. 15, 2026; FR-2026-01-15, PDF 2026-00677)