California SB 253 may require GHG reports starting 2026

Cleary Gottlieb memo explains that California’s SB 253 would require many U.S.-formed companies that do business in California to submit annual GHG emissions reports and third-party assurance, with the proposed first report covering fiscal year 2025 due by June 30, 2026 (subject to final regulations).

• Main action & timing: Companies that are Reporting Entities must file a GHG emissions report (Scope 1 and Scope 2) and obtain limited assurance covering the prior fiscal year; CARB’s current proposal targets a first filing by June 30, 2026 for fiscal year 2025, with Scope 3 disclosures beginning in 2027 (fiscal year 2026) and reasonable assurance for Scopes 1–2 plus limited Scope 3 assurance beginning in 2030 (fiscal year 2029).

  • Working group / rulemaking timeline: Aug 21, 2025 (working group session where deadlines were criticized); public comment closed Sep 11, 2025; CARB intends to publish Notice of Proposed Rulemaking Oct 14, 2025 (45-day APA comment period ending Nov 30, 2025); full board consideration Dec 11–12, 2025.

• Key thresholds, standards, and practical details: A Reporting Entity is any U.S.-formed business with total annual revenues > $1,000,000,000 that does business in California (CARB is still finalizing revenue definition), California sales threshold reference $735,019 (RTC sales threshold), and CARB’s current fee estimate per Reporting Entity is approximately $3,106 per year. CARB expects reports to follow Greenhouse Gas Protocol standards and accepts assurance standards such as ISSA 5000 (IAASB), AA1000, ISO 14060 family, and AICPA; CARB will not itself accredit verifiers but will rely on existing accreditation frameworks. Enforcement discretion will be exercised for the first-year incomplete reports if a company shows a good faith effort.