CA OAL approves first GHG reporting regulation under SB 253

On Oct. 12, 2026, the Office of Administrative Law (OAL) approved the California Corporate Greenhouse Gas Reporting and Climate‑Related Financial Risk Disclosure Initial Regulation, the first rule under Senate Bill 253 (SB 253). The regulation, promulgated by the California Air Resources Board (CARB) and codified at Title 17 of the California Code of Regulations, requires all reporting entities to submit a GHG inventory by a fixed deadline and to disclose the financial impact of climate risks. The rule applies to large corporate reporters, covering roughly 90% of California’s statewide GHG emissions. For firms with California clients, the change forces a rapid adjustment to ESG reporting frameworks and internal data collection processes. Firms should verify whether their clients already meet the reporting thresholds, establish or update GHG‑counting procedures, and prepare disclosure narratives for the new deadline. CPA, ESG, and sustainability counsel will likely see a surge in demand for compliance advisement and audit services as the industry races to meet the new requirement.