Article
July 30, 2026
Regulatory roundup: Key takeaways from CARB’s July 21, 2026 workshop on California SB 253
Our experts detail CARB's most recent workshop on California SB 253
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Alice Roberts
Senior Managing Consultant, GHG Emissions Lead
On July 21, 2026, the California Air Resources Board (CARB) held a public workshop providing additional details on implementation of the Climate Corporate Data Accountability Act (SB 253). The workshop addressed reporting timelines, scope 2 requirements, the phased approach to scope 3 reporting, assurance expectations, and considerations for the insurance industry. CARB’s proposed approach emphasized alignment with the GHG Protocol while recognizing the need for a practical transition toward improved GHG emissions data quality.
Reporting deadline and GHG accounting requirements
CARB proposed extending the initial SB 253 reporting deadline from August 10, 2026, to November 10, 2026. The November 10 deadline is expected to become the annual deadline for covered entities to report prior fiscal year GHG emissions.
The initial reporting cycle will focus on FY 2025 scope 1 and scope 2 emissions. Companies should use this additional preparation time to finalize inventories, confirm organizational boundaries, and document methodologies, emission factors, assumptions, and internal control procedures.
CARB’s proposed reporting framework aligns with the GHG Protocol Corporate Accounting and Reporting Standard and emphasizes transparency around:
- Organizational boundaries and consolidation approach
- Calculation methodologies and emission factors
- Data sources, estimates and missing data procedures
- Methodology changes and inventory recalculations
- Data quality controls and documentation
For scope 2 emissions, CARB is proposing alignment with the current GHG Protocol Scope 2 Guidance (2015), including reporting of both location-based and market-based emissions.
Scope 3 reporting: A phased approach
Recognizing the complexity of value chain emissions reporting, CARB is proposing a phased implementation approach rather than requiring companies to report all 15 GHG Protocol scope 3 categories immediately.
For the 2027 reporting cycle, CARB is considering requiring disclosure of five scope 3 categories that are broadly applicable across industries, commonly reported, and supported by established calculation methodologies:
- Category 1- Purchased Goods and Services
- Category 3 - Fuel- and Energy-Related Activities (not included in scope 1 or scope 2)
- Category 5 - Waste Generated in Operations
- Category 6 - Business Travel
- Category 7 - Employee Commuting
The remaining 10 scope 3 categories would initially remain voluntary while CARB evaluates future implementation.
This phased approach is intended to improve data quality, reduce the initial reporting burden, and allow companies time to develop supplier engagement strategies and stronger data collection processes.
CARB indicated that companies may use a range of calculation approaches aligned with the GHG Protocol, including supplier-specific data, activity-based calculations, spend-based estimates, and hybrid approaches. Companies will be expected to document methodologies, assumptions, limitations, and data quality considerations.
Assurance requirements
CARB provided additional clarity on assurance requirements under SB 253. The anticipated timeline includes:
- 2026 reporting cycle: Initial compliance flexibility as companies establish reporting processes
- 2027 reporting cycle onward: Limited assurance required for scope 1 and scope 2 emissions
- 2030 onward: Reasonable assurance required for scope 1 and scope 2 emissions, and limited assurance required for scope 3 emissions
CARB is considering several recognized assurance standards and frameworks.
- ISO 14064-3:2019 – Greenhouse Gas Validation and Verification
- ISO 14065 – Requirements for Validation and Verification Bodies
- ISAE 3410 – Assurance Engagements on Greenhouse Gas Statements
- ISAE 3000 (Revised) – Assurance Engagements Other Than Audits or Reviews of Historical Financial Information:
- AICPA AT-C Section 210 – Review Engagements
- AA1000 Assurance Standard (AA1000AS v3)
- IAASB ISSA 5000 – General Requirements for Sustainability Assurance Engagements
While ISSA 5000 is expected to influence future sustainability assurance practices, existing standards such as ISO 14064-3 and ISAE 3410 remain widely used for GHG emissions verification and assurance.
CARB’s final regulations will determine the specific assurance standards, accreditation requirements, and qualifications required for SB 253 assurance providers. assurance-ready documentation, including inventory management plans, internal control documentation, and supporting evidence to support future third-party verification activities. Companies should begin evaluating assurance readiness now rather than waiting for the final regulations.
Insurance industry considerations
CARB also addressed reporting considerations for insurance companies. Existing California Department of Insurance (CDI) climate reporting requirements may not fully satisfy SB 253 because CDI reporting does not include all required elements, including scope 3 reporting and third-party assurance requirements.
Insurance companies should prepare for SB 253 compliance beginning with the 2027 reporting cycle, including evaluation of scope 3 data availability and GHG Protocol alignment.
What companies should do now
Although the July workshop reflects proposed concepts rather than final requirements, organizations subject to SB 253 should begin preparing by:
- Finalizing FY scope 1 and 2 GHG inventories
- Confirming organizational boundaries and GHG accounting methodologies
- Strengthening data management processes and internal controls
- Developing or updating Inventory Management Plans
- Performing a Scope 3 screening assessment to identify the five proposed reporting categories and any additional relevant and material categories that could be included future years
- Improving supplier engagement and activity-based data collection
- Preparing documentation and controls to support future assurance
The July 21 CARB workshop confirmed that SB 253 implementation will follow a phased approach: first establishing consistent scope 1 and scope 2 reporting, then introducing targeted scope 3 categories beginning with the 2027 reporting cycle, while progressively expanding scope 3 emissions reporting and strengthening assurance readiness over time. Companies that begin building robust governance, documentation, and data processes now will be better positioned as California finalizes its regulations and expands reporting requirements in future years.
