California SB 253 and SB 261: Deadlines and Assurance

California has two climate disclosure laws aimed at large companies that do business in the state. SB 253 requires emissions reporting. SB 261 requires climate-related financial risk reports. They have different thresholds, different regulators' steps and, today, different legal status. This post uses the California Air Resources Board's (CARB) own documents, including its final regulatory order, which the Office of Administrative Law approved in October 2026.

SB 253: who reports and when

CARB's regulation defines a reporting entity as a corporation, partnership, limited liability company or other business entity formed under the laws of California, another US state, the District of Columbia or an act of Congress, with total annual revenues above $1 billion that does business in California. Revenue is the lesser of the entity's two previous fiscal years of revenue. A parent may file one consolidated report, and a subsidiary that qualifies need not file separately if the parent consolidates.

The first deadline is November 10, 2026

The regulation requires each reporting entity to report its Scope 1 and Scope 2 emissions on or before November 10, 2026. CARB moved the date from August 10 to November 10 in June 2026. Scope 3 reporting is not required for 2026.

Which fiscal year is reported depends on the year end:

A fiscal year that ends on or before February 1 of a calendar year: report the fiscal year ending in the current calendar year.
A fiscal year that ends after February 1: report the fiscal year ending in the previous calendar year. The entity may instead report its most recent fiscal year if the data is available.

For a calendar-year company, the report due November 10, 2026 covers the year ended December 31, 2025.

Two relief options for the first report only

For the November 10, 2026 report, the regulation lets a reporting entity submit either:

Scope 1 and Scope 2 emissions from its prior fiscal year that can be determined from information it already possessed, or was already collecting, on or before December 5, 2024; or
A statement on company letterhead that it is not submitting a report because it did not possess Scope 1 or Scope 2 information and was not collecting it on or before December 5, 2024.

December 5, 2024 is the date of CARB's enforcement notice, which said CARB would use enforcement discretion in the first cycle for entities that make good-faith efforts and retain data relevant to the prior fiscal year.

Assurance under SB 253

Limited assurance is not required for the 2026 report.

CARB staff have signaled that limited assurance on Scope 1 and 2 would start in a later reporting year, with the standards under discussion including AICPA attestation standards, ISAE 3000 (Revised) and ISAE 3410, ISSA 5000, ISO 14064-3 and AccountAbility's AA1000. Those are staff concepts for later rulemaking, not adopted rules. For audit firms the point is that the AICPA standards are on the list, which makes the AICPA sustainability attestation drafts and ISSA 5000 directly relevant.

SB 261: on hold

SB 261 covers covered entities: business entities with total annual revenues above $500 million that do business in California, measured, as with SB 253, by the lesser of the two previous fiscal years. Entities regulated by the California Department of Insurance, or in the business of insurance in any other state, are excluded.

On November 18, 2025, the Ninth Circuit granted an injunction against enforcing SB 261 while the appeal in Chamber of Commerce v. Sanchez is pending. CARB's docket page says CARB will not enforce Health and Safety Code section 38533 against covered entities that did not post and submit reports by the January 1, 2026 deadline. The docket remains open for voluntary submissions from December 1, 2025 through December 31, 2026. The Ninth Circuit's order granted the injunction as to SB 261 and denied it as to SB 253.

What a CPA firm does this week

Identify clients over $1 billion in revenue with California operations. Apply the lesser-of-two-years test to their own revenue figures.
For each, establish what Scope 1 and 2 data existed on December 5, 2024. That date decides which relief option is open.
Check the fiscal year rule against the client's year end and document which year the report covers.
Sort clients between $500 million and $1 billion. They are SB 261 covered entities only. With the injunction in place, any submission is voluntary.
Agree the assurance path with clients that want it early. Limited assurance is not required for the first report. An engagement is a voluntary attest engagement, with suitable criteria and independence requirements. See ESG assurance for CPAs and independence and nonattest services, since building the inventory and assuring it for the same client raises a self-review threat.

Worked example of the revenue test

All figures are illustrative. A company reports revenue of $1.15 billion in the latest fiscal year and $940 million in the year before. The lesser is $940 million. It is below $1 billion, so it is not an SB 253 reporting entity on that test, and above $500 million, so it is an SB 261 covered entity. A year later, if the two prior years are $1.15 billion and $1.2 billion, the lesser is $1.15 billion and it is a reporting entity.

FAQ

Is limited assurance required for the November 10, 2026 report?

No. Limited assurance is not required for the first report.

Does the SB 261 injunction affect SB 253?

No. The Ninth Circuit order covers SB 261.

What if a company never collected emissions data?

The regulation allows a letterhead statement for the first report if the company did not possess or collect Scope 1 or Scope 2 information on or before December 5, 2024.

Sources

CORAA prepares ready-to-review audit files for US CPA firms from QuickBooks books; you review and sign. See /us.

Part of CORAA University · Completion and reporting: related guides, calculators and templates.

AU-C references are to AICPA Professional Standards, paraphrased here; read the standard itself before relying on a requirement. This page is guidance, not professional advice. Report an error

California SB 253 and SB 261: Climate Disclosure Deadlines and Assurance for CPAs