California SB 253 — First Scope 1+2 Emissions Reports

What this countdown tracks

The clock above counts down to the first mandatory disclosure deadline under California's SB 253, the Climate Corporate Data Accountability Act, on Monday, August 10, 2026. By this date, US-domiciled companies with more than $1 billion in global revenue that "do business in California" must publish their Scope 1 and Scope 2 greenhouse-gas emissions for fiscal year 2025, verified by an accredited third-party assurance provider at limited-assurance level.

About this regulation

SB 253 was signed by Governor Gavin Newsom on October 7, 2023 and amended by SB 219 in September 2024 to give CARB additional rulemaking flexibility on the deadline structure. The California Air Resources Board (CARB) is responsible for the implementing regulation, which was put out for public comment in late 2024 and finalized in 2025 after several stakeholder workshops. The law applies to roughly 5,400 companies based on California Department of Tax and Fee Administration (CDTFA) revenue thresholds and broad "doing business" criteria from the California Revenue and Taxation Code.

The disclosure regime is two-tiered. Scope 1 (direct emissions from owned operations) and Scope 2 (purchased electricity, steam, heating, cooling) reports begin in 2026 covering FY2025. Scope 3 (value-chain emissions) reports begin in 2027 covering FY2026. Reports must use the GHG Protocol as the foundational standard with CARB-specified accreditation for assurance providers. The law was upheld in federal court in early 2025 against a US Chamber of Commerce challenge alleging First Amendment violations; the appeal continues but did not block 2026 implementation.

What changes

By August 10, 2026:

• Filings published on a publicly searchable registry maintained by CARB or a designated reporting body.
• Scope 1 and 2 in metric tons CO2e, with limited assurance.
• Penalties up to $500,000 per reporting year for non-filing; reasonable-best-efforts safe harbor for first cycle.
• Scope 3 reporting begins in 2027 and ramps up to "reasonable assurance" by 2030.
• Methodology: must use the GHG Protocol Corporate Standard.

Past milestones

• March 2025: CARB final implementing regulation adopted.
• October 2024: Governor Newsom signs SB 219 amending implementation timelines.
• October 2023: Newsom signs SB 253 (and the companion SB 261 climate-related financial-risk law).
• January 2024: California Chamber of Commerce files First Amendment challenge in federal court.
• January 2025: District court denies preliminary injunction.

How to follow

Official rulemaking docs at ww2.arb.ca.gov/rulemaking, with the SB 253 / SB 261 docket on the CARB Public Documents portal. Industry tracking from PwC, Deloitte, KPMG, EY, and the Sustainable Business Council of California. Coverage from Bloomberg Green, Reuters Sustainable Business, and the LA Times Climate.

Related countdowns

Pair this with peer disclosure-regime pages: CSRD Wave 2 first reporting 2028, EU EUDR application 2026, EU CRA application 2027, GDPR 10-year evaluation 2028, and EU CBAM first certificate surrender 2026.

FAQ

When are the first SB 253 reports due? Monday, August 10, 2026, covering FY2025 Scope 1 and Scope 2 emissions. Where does the law apply? Companies "doing business in California" with global revenue over $1B — applying broadly to US Fortune 1000 companies. Why does SB 253 matter? It is the first US jurisdiction to impose mandatory, verified Scope 1+2 (and later Scope 3) emissions disclosure on private companies, complementing the SEC climate-disclosure rule paused in 2024. Does it apply to non-US companies? Yes, if they are doing business in California and meet the revenue threshold, regardless of state of incorporation.