The California Air Resources Board (CARB) has proposed amendments to the Regulation for the Mandatory Reporting of Greenhouse Gas Emissions (MRR) to clarify reporting requirements and collect additional data to improve the accuracy and completeness of statewide GHG emissions inventories. The proposed amendments expand program applicability, incorporate new fuel pathways and technologies, and introduce additional reporting obligations for several regulated sectors. Notable changes include the following:
Expanded supplier definitions and fuel coverage
- Broaden the definition of “supplier” to include importers of cement and hydrogen, suppliers of imported LPG, and suppliers of biomass‑derived natural gas, natural gas liquids, LNG, CNG, and hydrogen.
- Expand transportation fuel regulation to include biomass‑derived fuels and in‑state production facilities supplying fuel outside the terminal system.
New reporting requirements for biomass‑derived fuels
- Require reporting of LCFS pathway codes, fuel types, and points of regulation for all reported biomass‑derived fuel volumes.
- Clarify and expand reporting of biogenic CO2 emissions, including separate identification of direct CO2 emissions from the consumption of biomass‑derived fuels.
- Require purchased biomethane to be identified as exempt or non‑exempt.
Additional reporting obligations for cement and refining sectors
- Require cement producers to report annual consumption of supplementary cementitious materials (SCMs), and SCM manufacturers to report production and delivery quantities.
- Revise refinery product data reporting, transitioning from complexity‑weighted barrel metrics to liquid fuel and asphalt production data.
- Incorporate biorefining and coprocessing of biomass‑derived feedstocks into refinery reporting requirements.
Inclusion of new fuels and emerging technologies
- Require reporting of emissions from novel and low‑carbon fuels not currently covered under existing supplier categories.
- Add definitions and requirements for electricity imports routed through energy storage systems prior to import.
Verification and administrative updates
- Establish eligibility criteria for remote site visits for low‑risk reporters.
- Allow verification site visits once every three years, rather than every compliance period.
CARB has released preliminary rulemaking materials, including the Staff Report (Initial Statement of Reasons) and the proposed regulatory text for each regulation on the Cap-and-Invest Regulation webpage and Mandatory GHG Emissions Reporting Regulation webpage. Also, a public hearing is scheduled on May 28, 2026, to consider its proposed amendments to the MRR, and the public written comment period will start on January 23, 2026 through March 9, 2026.
If you would like to discuss the MRR Amendments and how they may impact your facility, please email Charles Lee in Trinity’s Irvine office or call 949.567.9880.
