California Updates SB 253: CARB Webinar Takeaways

The California Air Resources Board (CARB) held a workshop today to explain more about what to expect for reporting and assurance requirements in its upcoming regulations.  CARB staff also detailed the “next steps” of their rule development process.  The webinar slides are already posted on CARB’s workshop webpage, but in the meantime here’s nine of our most important takeaways: 

1. Guidance for 2026 reporting:  CARB has committed to issuing additional guidance materials by September 1 to help companies prepare for the November 1, 2026 reporting deadline.

   
   

2. GHG Protocol Relevance: CARB is tying its reporting requirements closely to the GHG Protocol provisions, and during the presentation specifically referred to the GHG Protocol Corporate Standard, Scope 2 guidance, and Scope 3 guidance.  A key focus for CARB has been the “interoperability” with other standards and reporting requirements. That said, CARB is prohibited from adopting a “dynamic” regulation that will automatically incorporate the current version of the standards as they are revised, so the SB 253 reporting may often refer to an “old” version of the standards.

   
   

3. Scope 3 Categories: CARB is proposing to use the five most commonly-reported Scope 3 categories.  These include Category 1 (purchased goods and services), Category 3 (fuel and energy-related activities), Category 5 (waste generated in operations), Category 6 (business travel), and Category 7 (employee commuting). 

   
   

4. Use of Other GHG Emissions Reports: If reported under other regulatory programs, such as CARB’s Mandatory Reporting Regulation (MRR), those reports may be submitted to satisfy SB253 requirements so long as it is explained as part of the submittal.

   
   

5. Dealing with Data Uncertainty: Measurement uncertainty and missing data substitution must be explained, including the basis for approach and any assumptions made.

   
   

6. Dealing with De Minimis Data: Non-relevant data may be excluded; however, any data exclusions must be explained and quantified if possible.  This appears to address prior comments about whether de minimis thresholds will be imposed.

   
   

7. Reporting Deadline: The reporting deadline is November 10, 2026.  The workshop appeared to suggest that this will be the reporting deadline going forward written into the regulation (see Slide 23).

   
   

8. Assurance Standards: Information was presented on assurance standards and assurance reports. The assurance standards are AA1000AS v3, AICPA AT-C Section 210, ISAE 3410, ISSA 5000, and ISO 14064-3:2019.  ALG follows the ISO 14064-3 as it is very closely aligned with the MRR and Low Carbon Fuel Standard (LCFS) verification procedures that are already implemented by CARB.

   
   

9. Next Steps: There are six upcoming listening sessions CARB will be hosting between early August and early September. The listening sessions are broken into groups of different stakeholders and regulated entities and are intended for CARB to receive feedback as they develop the regulation. In terms of the next steps in the regulation, no specific dates were provided but CARB intends to re-release the rule package from earlier this year for a 15-day public comment period at some point in the future. There will be a second regulatory package with the “nuts and bolts” of the regulation at a later date that will include a 45-day comment period. 

   
   

For companies like ALG that regularly report and verify GHG emissions, some of this is “old hat”, while some of it will be quite new for regulated businesses.  We would be happy to chat about your specific situation and share what we have seen from the hundreds of businesses we work with. Email our SB253 subject matter expert, Elliott Ripley, at eripley@algcorp.com.