CARB Sets Out Scope 3 Options
CARB’s 23 March workshop brought the next stage of SB 253 into clearer focus. The discussion moved beyond first-year Scope 1 and Scope 2 reporting and towards the options under consideration for Scope 3.
The California Air Resources Board (CARB) used its 23 March workshop to set out options for bringing Scope 3 greenhouse gas reporting into Senate Bill 253 implementation from 2027 onwards. The move follows CARB’s 26 February approval of the initial regulation and turns attention from first-year Scope 1 and Scope 2 compliance to the design of the next phase.
At this stage, the live regulatory question is how CARB phases and specifies Scope 3 reporting from 2027 under Health and Safety Code section 38532.
From Initial Regulation to the Next Design Stage
The 23 March 2026 workshop formed part of CARB’s work on the California Corporate Greenhouse Gas Reporting Program under Senate Bill 253, as amended by Senate Bill 219. The session covered the 10 August 2026 Scope 1 and Scope 2 reporting deadline and the next stage in regulatory development for 2027–2030 greenhouse gas reporting requirements under HSC section 38532.
The March materials make clear that this next stage is not yet final rule text. CARB presented staff concepts for public feedback on greenhouse gas accounting, Scope 3 reporting options, Scope 1 and 2 assurance, and economic analysis that would feed into formal rulemaking. The workshop page also set a 13 April 2026 deadline for written comments. The sources therefore distinguish between the underlying statute and the implementing regulation now being developed around it.
What is Settled and What Remains Open
In February, CARB said it approved the California Greenhouse Gas Reporting and Climate Financial Risk Disclosure Initial Regulation, which established administration and implementation fees, key definitions for programme application, and the first-year reporting deadline. That was CARB’s initial implementing step under SB 253.
Scope 3, by contrast, remains under active development. The workshop page and presentation describe the March discussion as preliminary staff options and requests for feedback, not as final requirements. The mandatory near-term element identified in the sources is first-year SB 253 reporting on Scope 1 and Scope 2 emissions, due by 10 August 2026. CARB also says it will use enforcement discretion for good-faith first-year submissions.
Who is in Scope and When
CARB’s March slides restate the statutory scope of SB 253 as applying to US-based entities doing business in California with more than $1 billion in annual revenue and requiring disclosure of Scope 1, 2 and 3 greenhouse gas emissions. The February release also identifies exempt entities, including tax-exempt non-profits and charities, government or majority-owned government entities, and certain insurance-related businesses. For 2027 onwards, the March deck sets out three ways to phase in Scope 3: across all reporting entities from 2027, by sector, or by category.
Why the March Workshop Matters
The March workshop shifts the focus from the administrative baseline to the design of Scope 3 reporting. For non-financial reporting teams, the question is now less about the existence of SB 253 than about the reporting model CARB is likely to build around it.
CARB also places the regime in a comparability and transparency context. In its February release, the Board says the regulation is intended to provide investors and consumers with reliable information and to align California with other jurisdictions requiring climate-related transparency.
What this Changes for Reporting Teams
The March materials point to three linked areas: methodology, evidence and assurance readiness. CARB asks for feedback on organisational boundaries, accounting methods, emission factors, de minimis treatment and assurance standards. In the current rulemaking, staff concepts cover limited assurance for Scope 1 and Scope 2 starting in 2027, while SB 253 assurance requirements slated for 2030 are not part of this rulemaking. For reporting teams, that creates a short list of decisions: who owns methodological choices, what data can support them, how those judgements would be explained in disclosures, and what still depends on the next rulemaking stage.
The sequence is becoming clearer even though the final Scope 3 model is not. First comes mandatory Scope 1 and Scope 2 reporting. The next decisions concern which Scope 3 entities or categories come into scope first, what supporting disclosures CARB will expect, and how assurance and economic analysis will be reflected in formal rulemaking.
External Reference Points
CARB’s March materials do not set out a full interoperability model, but they do refer to other standards and frameworks in discussing reporting and assurance, including IFRS S1/S2, EU CSRD, ISSA 5000 and ISO 14064-3. For preparers, the immediate point is that California is developing its approach in a reporting environment where comparability across disclosure systems already matters.
The next question is how CARB will reflect its Scope 3 options in formal rulemaking for 2027–2030.
