The California Air Resources Board has extended the first reporting deadline under the state's corporate climate disclosure law, SB 253, by three months to November 10, 2026, from the original date of August 10. CARB published guidance for the 2026 reporting cycle in September and opened an optional online intake platform for companies to submit their data, according to the agency and law firm summaries.
SB 253, the Climate Corporate Data Accountability Act, signed in 2023, requires companies with more than $1 billion in annual revenue that do business in California to report their greenhouse gas emissions. The first cycle covers Scope 1 direct emissions and Scope 2 emissions from purchased electricity for the prior fiscal year. Reporting of Scope 3 emissions, from supply chains and product use, begins in 2027.
First-year flexibility
CARB said it is exercising enforcement discretion in the first year. It will accept reports without the limited assurance from a third party that the law requires, and it will allow companies that were not collecting the necessary data as of December 5, 2024, to submit a statement saying they cannot report, rather than a full report, according to the guidance and summaries by BDO, White & Case and Ropes & Gray. That date corresponds to an earlier CARB enforcement notice.
The extension and flexibility reflect the short time between the adoption of CARB's implementing regulations and the original deadline, and requests from businesses for more time to prepare.
Scope of the law
The revenue threshold of $1 billion captures several thousand companies, including many headquartered outside California. Companies must report using the Greenhouse Gas Protocol standards. CARB is charged with collecting fees to fund its administration of the program and with making the data public through a reporting platform.
A companion law, SB 261, requires companies with more than $500 million in revenue to publish reports on climate-related financial risks. A federal appeals court paused enforcement of SB 261 in late 2025 while litigation brought by business groups proceeds. SB 253 has not been paused.
Legal challenges
The US Chamber of Commerce and other business groups sued to block both laws, arguing that they violate the First Amendment by compelling speech and that they intrude on federal authority over interstate commerce. The litigation is ongoing. The outcome will determine whether California's disclosure regime can be enforced in full.
At the federal level, the Securities and Exchange Commission adopted a climate disclosure rule in 2024 but stopped defending it in court in 2025, leaving state laws and international standards as the main sources of mandatory climate reporting for US companies.
Why it matters for energy
For energy companies, Scope 1 reporting covers emissions from their own operations, such as power plants, refineries, pipelines and production facilities. Many large energy companies already report these emissions under the EPA's Greenhouse Gas Reporting Program, though the administration has proposed ending most of that program. If federal reporting is reduced, SB 253 would become one of the main public sources of facility-level emissions data for companies operating in the state.
For technology companies, Scope 2 reporting covers the electricity used by data centers and offices. Companies may report both location-based figures, reflecting the average emissions of local grids, and market-based figures, which account for renewable energy purchases. The gap between the two is large for data center operators. Google, Microsoft and Amazon reported in their 2026 sustainability reports that their electricity use or emissions rose with data center growth, and their SB 253 filings will provide a standardized view of those figures.
Utilities and Scope 2
Electric utilities play a dual role under the law. Their own generation appears in Scope 1, while their customers' purchased electricity appears in those customers' Scope 2. Large companies increasingly ask utilities for supplier-specific emission factors and for green tariffs that allow them to claim lower Scope 2 emissions.
Interaction with other regimes
Large multinational companies also face reporting under the EU Corporate Sustainability Reporting Directive, although its scope was narrowed in late 2025 to companies with more than 1,000 employees and €450 million in turnover. Many countries are adopting the International Sustainability Standards Board's climate disclosure standard. Companies subject to several regimes are trying to align their data collection so that one set of numbers can meet multiple requirements.
Federal data gap
The EPA's Greenhouse Gas Reporting Program, in place since 2010, collects emissions data from more than 8,000 large facilities, including power plants, refineries and oil and gas operations. In 2025 the agency proposed eliminating reporting requirements for most source categories. If that proposal is finalized, the federal dataset that analysts, investors and states rely on would shrink sharply. State programs such as SB 253 differ from the federal program because they collect data at company level rather than facility level, but they would become one of the few mandatory public sources for many companies' emissions.
Costs of compliance
CARB's regulations set annual fees for reporting entities to fund the program. Companies also bear the cost of data collection and, from 2026 onward, third-party assurance. Business groups have argued that the costs are significant, especially for Scope 3. Supporters of the law have argued that many large companies already calculate these figures for voluntary reporting or for other jurisdictions.
Assurance
The law requires limited assurance for Scope 1 and Scope 2 emissions from 2026, rising to reasonable assurance from 2030, and limited assurance for Scope 3 from 2030. CARB's first-year discretion on assurance means many initial reports will be unaudited. Assurance providers, including accounting firms and specialist verification bodies, have been building capacity for the expected demand.
Data quality and comparability
Companies use different methods to estimate emissions, particularly for Scope 2 and Scope 3. The Greenhouse Gas Protocol is revising its standards, including rules on how companies account for renewable energy purchases. Changes could affect how technology companies report data center emissions, especially if hourly matching of clean power with consumption becomes a requirement for market-based claims.
What to watch
Key items include the number of companies that file by November 10, how many submit statements instead of full reports, the progress of litigation against SB 253 and SB 261, and CARB's rules for Scope 3 reporting in 2027. The publication of the data will allow comparison of emissions across companies doing business in the world's fourth-largest economy.