CARB Sketches the 2027 SB 253 Regime — a Scope 3 Compromise That Drew Fire From Both Sides

The July 21 workshop in plain English

• CARB answered the biggest open question about 2027. Scope 3 reporting starts with five of the fifteen GHG Protocol categories — purchased goods and services, fuel- and energy-related activities, waste, business travel, and employee commuting — with the other ten voluntary and a data-exclusions provision softening the edges.
• Assurance became concrete. From reports submitted in 2027, Scope 1 and 2 disclosures need limited assurance from an independent third party, under one of five named standards. Provider rotation and conflict-of-interest disclosure are still open questions CARB is asking about.
• Insurers come off the sidelines. Staff concluded the Department of Insurance’s climate survey won’t satisfy SB 253 from 2027, and propose letting insurers file one report to satisfy both regulators.
• The compromise satisfied no one fully — industry commenters said five categories is still too much (or the wrong five); advocates said it’s too little, with no date certain for the rest. That argument now moves to a 45-day comment period this fall.
• The calendar is the real news. Filing infrastructure for the 2026 report arrives by September 1; six sector listening sessions run August 5–September 9; the formal staff proposal publishes this fall; Board consideration is targeted by year-end — and November 10 is proposed as the recurring annual deadline, not just 2026’s.

On July 21, 2026, CARB held a three-hour virtual workshop previewing the “Subsequent Regulation” — the rulemaking that will govern SB 253 greenhouse-gas reporting in 2027 and beyond, when Scope 3 and assurance requirements switch on. Staff presented draft regulatory language across general reporting requirements, Scope 3, assurance, and exemptions, and committed to a schedule: a full staff proposal (staff report, economic analysis, and complete draft text) this fall, a 45-day public comment period, and Board consideration targeted by the end of the year. It is a separate track from the still-unfinished Initial Regulation covering 2026 — more on that below.

Five of fifteen: the Scope 3 compromise

In March, staff had floated three options for Scope 3: broad applicability, a sectoral phase-in, or a category phase-in. They chose the third. Starting in 2027, reporting entities would disclose the five most commonly reported categories — purchased goods and services (Category 1), fuel- and energy-related activities (3), waste generated during operations (5), business travel (6), and employee commuting (7) — chosen because they apply across most sectors, have relatively mature calculation methods, and often draw on data companies already collect. The other ten categories may be reported voluntarily, and a data-exclusions provision, applying the GHG Protocol’s five accounting principles, lets companies omit emissions whose absence could not reasonably influence a user’s understanding. Staff also confirmed a point that matters for risk assessment: the statute limits Scope 3 penalties to non-filing.

The public comment period showed why this lands as a compromise rather than a settlement. From industry: the California Chamber of Commerce argued that purchased goods and services is the broadest, most data-intensive, and least mature category — a hard place to start — and pushed for entity-selected categories under a materiality framework; United Airlines argued the five lose all nuance for atypical sectors (an airline’s business-travel emissions largely sit in its own Scope 1); California Dairies asked for a farmer-cooperative exemption, citing immature methodologies and double-counting across the dairy supply chain. From the other direction: Ceres and California Environmental Voters pressed for full fifteen-category reporting or, failing that, a date certain — 2028 was suggested — for the rest; EDF urged strengthening the proposal to capture at least 95% of Scope 3 emissions. Staff offered no date for full Scope 3. That absence, flagged by three separate commenters, is the likeliest pressure point in the fall comment period.

Assurance gets standards — and two open questions

Beginning with reports submitted in 2027, Scope 1 and 2 disclosures (including separately reported biogenic CO2) require limited assurance from an independent third party, conducted in full conformance with one of five standards: AA1000AS v3, AICPA AT-C Section 210, ISAE 3410 with ISAE 3000 (Revised) for engagements commencing before December 15, 2026, ISSA 5000 for engagements commencing on or after that date, or ISO 14064-3:2019. A reasonable-assurance engagement satisfies the requirement. Staff noted in the Q&A that the engagement covers the full Scope 1 and 2 submission — quantitative and qualitative portions alike — and emphasized the approach is not finalized. Two questions CARB explicitly asked for feedback on: whether five standards with different accountability architectures (professional licensure, organizational accreditation, engagement-level licensing) produce comparable outcomes, and whether assurance providers should be required to rotate or disclose other services — tax, audit, consulting — performed for the reporting entity.

Insurers: the exemption’s logic expires in 2027

The Initial Regulation exempted insurance companies from 2026 reporting to avoid duplicating the Department of Insurance’s climate disclosures, and the Board directed staff (Resolution 26-1) to evaluate the overlap with CDI. Staff reported back: the CDI survey is built on the NAIC’s TCFD-based framework, which addresses governance and strategy broadly but carries far less detailed GHG accounting than the Greenhouse Gas Protocol — and it includes neither Scope 3 nor assurance. The exemption’s rationale therefore doesn’t carry into 2027. The proposal: from 2027, insurers may submit one report satisfying both CDI and CARB, supplementing wherever the CDI filing falls short of SB 253’s requirements. Insurance trade groups at the workshop (APCIA, the Personal Insurance Federation of California) signaled support for the aligned approach while pressing for streamlined submission mechanics.

The fine print from the Q&A

Four staff answers deserve their own line. November 10 is proposed as the recurring annual reporting deadline for 2027 and onward — the date born as a 2026 deferral would become permanent, and staff are openly soliciting feedback on it. The baseline year would be 2027, the program’s first reporting year. Reported emissions are global, not California-only — the statute reaches a covered entity’s worldwide operations, a point two multinational commenters asked about. And regulatory references will freeze at adoption-date versions: California rulemaking cannot dynamically incorporate a standard’s future revisions, so CARB will cite the 2015 Scope 2 guidance — not the GHG Protocol update now in progress — and future protocol revisions would require a new rulemaking to adopt. For companies aligning one inventory across multiple jurisdictions, that last one is the quiet interoperability caveat in an otherwise interoperability-forward proposal.

Meanwhile, 2026 is still unfinished

The workshop’s other storyline is what didn’t move. The revised Initial Regulation — withdrawn from OAL on June 24 for “clarifying changes” — remains unpublished, and staff would not say when it or its 15-day comment notice will appear, only that an announcement is coming. That leaves the November 10, 2026 deadline formally proposed rather than final, and it leaves companies in the position one commenter described bluntly: guidance materials arrive September 1, seventy days before the filing deadline. (One trade association asked CARB to push first-year reporting to November 2027 outright.) What companies do now have: a commitment that the voluntary online intake platform, a guidance document, and an instructional video arrive by September 1, 2026, and a reminder that the December 2024 enforcement notice — report what you were collecting as of that date — still governs year one.

What to watch next

In order: the 15-day comment package on the revised Initial Regulation, which can land any day and finally fixes (or moves) November 10; the September 1 filing-infrastructure release; the six sector listening sessions running August 5 through September 9; the fall staff proposal that turns these concepts into actual regulatory text with a 45-day comment period; and Board consideration by year-end. Behind all of it, the Ninth Circuit’s ruling in Chamber of Commerce v. Sanchez — argued January 9, still pending — could reshape the SB 261 half of the program at any moment. Every development lands on the tracker’s changelog with the primary source attached.

Primary sources: July 21, 2026 workshop slides (CARB) · Workshop public notice (CARB bulletin) · Workshop recording · CARB Climate Disclosure Program · CARB program news (June 24, 2026 deferral notice)