California SB 253: Who Must Report Emissions, and When

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California’s SB 253 is the first law in the United States that makes companies publish their greenhouse gas emissions. Every US company with more than $1 billion in annual revenue that does business in California has to report its Scope 1 and Scope 2 emissions for the prior fiscal year, measured to the Greenhouse Gas Protocol. The first reports were due August 10, 2026, until the California Air Resources Board announced on June 24 that it would push the deadline to November 10, 2026, through a short revision that still needs approval from the state’s Office of Administrative Law.

The disclosure is mandatory. The SEC retreated from its federal climate disclosure rule in early 2025. California didn’t.

Key findings

California SB 253 requires companies with $1 billion or more in annual revenue doing business in California to disclose Scope 1 and Scope 2 GHG emissions for their prior fiscal year. CARB’s proposed first deadline is November 10, 2026, moved from August 10.
The California Air Resources Board adopted its implementing regulation in February 2026 and withdrew it from state review to make clarifying changes; the revised package needs Office of Administrative Law approval.
CARB staff estimate that roughly 2,600 companies are subject to SB 253.
Scope 3 (value chain) emissions reporting is required beginning with fiscal year 2026 data, reported in 2027.
No independent assurance is required for the first reports. Limited assurance starts with reports filed in 2027, reasonable assurance in 2030.
CARB said in December 2024 it will not penalize incomplete first-year reports from companies making a good-faith effort. The statute caps administrative penalties at $500,000 per reporting year.
The SEC abandoned its climate disclosure rule in March 2025; California proceeded independently.
New York’s Climate Corporate Data Accountability Act passed the state Senate in February 2026; it was before the Assembly as of June 2026.

What SB 253 actually requires companies to disclose

The Greenhouse Gas Protocol divides emissions into three categories.

Scope 1 covers direct emissions from sources the company owns or controls: on-site combustion, company vehicles, industrial processes, refrigerant leaks. A manufacturer’s factory furnaces are Scope 1. An airline’s jet fuel burn is Scope 1.

Scope 2 covers indirect emissions from purchased electricity, heat, steam, and cooling. The emissions happen at the power plant, but the company’s electricity use drives them.

Scope 3 covers value chain emissions: supplier production, customer use of the product, employee commuting, business travel, waste disposal. For most companies, Scope 3 is 70 to 90 percent of their total climate footprint. A clothing company’s Scope 3 includes the cotton farming, textile manufacturing, shipping, laundering by consumers, and eventual disposal of every garment. Scope 3 is where the hard accountability lies.

The first reports cover Scope 1 and 2 only. Scope 3 follows in 2027.

Industrial factory with smokestacks emitting white steam against a gray sky — Scope 1 emissions are direct emissions from sources a company controls. Under SB 253, companies with $1 billion or more in revenue must now report these in conformance with the Greenhouse Gas Protocol, with the first reports due in 2026. Voluntary ESG reports used their own methodologies. Mandatory disclosure requires a standardized, auditable approach. *Photo: Pixabay via Pexels. Pexels License.*

Why mandatory disclosure is different from voluntary ESG reporting

Most large US companies already publish greenhouse gas emissions data. Every S&P 500 company with a sustainability report includes some emissions information. CDP (formerly Carbon Disclosure Project) collects voluntary disclosures from thousands of companies annually. The Task Force on Climate-related Financial Disclosures (TCFD) framework has been widely adopted.

The voluntary system has a structural problem. Companies disclose what they choose to disclose, using the methodology they choose, in the format they choose. As of 2025, approximately 87 percent of S&P 500 companies disclosed some climate-related targets, per available analysis. But “climate-related targets” covers a wide range of specificity and verifiability. A company can publish a “net zero by 2050” commitment with no interim milestones, no Scope 3 disclosure, and no audited baseline.

SB 253 changes the structure. Mandatory means every qualifying company, not just the ones with favorable data. Standardized means all reports use the Greenhouse Gas Protocol, not each company’s preferred methodology. Verified means independent assurance providers check the data, at a limited level from 2027 and a reasonable level from 2030. Comparable means analysts, investors, and journalists can compare Company A’s disclosed Scope 1 emissions to Company B’s, on the same basis.

The distance between what companies have been claiming and what mandatory standardized disclosure produces is the accountability gap this law is designed to close.

Financial chart showing an upward trend with data metrics highlighted — Many companies have published voluntary GHG emissions data in sustainability reports for years. SB 253 mandates standardized reporting under the Greenhouse Gas Protocol, with third-party verification required starting in 2027. The difference between voluntary disclosure and mandatory standardized disclosure is the difference between a press release and an audit. *Photo: Arturo A via Pexels. Pexels License.*

Who qualifies and what “doing business in California” means

California law defines “doing business in California” broadly. A company qualifies if it:

Is incorporated in California
Is registered with the California Secretary of State
Has California sales, property or payroll above the Franchise Tax Board’s doing-business thresholds, which rise with inflation every year

Given California’s economic scale, roughly the fifth-largest economy in the world at approximately $4 trillion in GDP, nearly every US Fortune 500 company does business in California by at least one of these definitions. The law is, in practice, a national disclosure requirement administered at the state level.

CARB staff estimate that roughly 2,600 companies are subject to SB 253, based on a preliminary list CARB published in September 2025 and says is not definitive. That covers most of the companies whose voluntary sustainability commitments have been analyzed, discussed, and sometimes disputed over the past decade.

David Wallace-Wells documents in The Uninhabitable Earth that the gap between corporate climate commitments and actual emissions trajectories has been persistent and large. Mandatory standardized disclosure creates, for the first time, a federal-equivalent mechanism in the largest US state for measuring that gap.

Large solar panel array in a field representing renewable energy generation — Many companies have announced renewable energy investments and net-zero commitments. SB 253 disclosures will reveal whether those announcements correspond to actual reductions in Scope 1 and Scope 2 emissions, or whether the emissions trajectory has continued upward despite the public commitments. *Photo: Wikideas1 via Wikimedia Commons. CC0.*

The SEC’s retreat and California’s advance

In March 2025, the SEC voted to end its legal defense of the federal climate disclosure rules it had finalized in 2024. The federal rule, designed to require climate-related financial disclosures from public companies, was stayed and effectively abandoned.

The state-federal divergence created by the SEC’s retreat means California’s law now operates without the backstop a parallel federal requirement would have provided. Companies cannot satisfy SB 253 by pointing to federal compliance. They must comply with California specifically.

New York passed Senate Bill 9072A, its own Climate Corporate Data Accountability Act, in February 2026. If signed into law and withstanding anticipated legal challenges, it would impose similar disclosure requirements on companies doing business in New York. The bill was before the Assembly as of June 2026.

The pattern is state-level mandates advancing while federal rules retreat, which is the same dynamic that produced California’s vehicle emissions standards decades before federal fuel economy standards caught up.

What the first disclosures will reveal

The first deadline, now proposed for November 10, 2026, is first-year only and Scope 1 and 2 only, with no assurance required and CARB’s enforcement discretion applied to good-faith filers. The first round of disclosures will not be the complete accountability picture.

But they will reveal something specific: whether companies have the measurement infrastructure to know what their Scope 1 and 2 emissions actually are. A company that has been publishing annual sustainability reports with net-zero commitments but cannot produce Scope 1 and 2 numbers by the first deadline has revealed that its reporting infrastructure did not match its public claims.

That’s the accountability test embedded in the first deadline.

Paul Hawken’s Drawdown catalogs the mechanisms by which actual emissions reductions can be achieved, sector by sector. The first SB 253 disclosures will reveal which companies are on a trajectory toward those reductions and which are publishing commitments without the underlying data to verify them.

An audience seated in a darkened conference hall under stage lights — Corporate climate commitments have been made in conference rooms and at international forums for more than a decade. SB 253 moves the accountability from voluntary declaration to mandatory verified disclosure. Whether conferences produce different behavior once the data is public is the question the next few years will answer. *Photo via Unsplash. Unsplash License.*

The WokeCorp assessment

The commitment. California’s SB 253 creates the first standardized, mandatory, verified corporate climate disclosure requirement in the United States. It reaches roughly 2,600 companies by CARB’s own estimate. The first Scope 1 and 2 deadline, now proposed for November 10, 2026, is the first enforcement point in a multi-year implementation schedule.

The gap it closes. Voluntary ESG reporting allowed companies to publish selectively, use self-chosen methodologies, and make commitments without audited baseline data. SB 253 eliminates that flexibility for qualifying companies. The gap between voluntary disclosure and mandatory standardized disclosure is where the accountability mechanism lives.

What comes next. Scope 3 in 2027. Limited assurance in 2027, reasonable assurance from 2030. Administrative penalties of up to $500,000 per reporting year. The first deadline is the entry point, not the full picture. Whether the disclosures produce accountability or produce a new category of compliant-but-uninformative reports is what the next two years will show.

See Net Zero Theater for the documented gap between corporate climate pledges and corporate lobbying against climate policy.

Net Zero Theater, the gap between corporate climate pledges and actual emissions trajectories
How ESG Ratings Work, the voluntary disclosure system SB 253 now supplements with mandatory reporting
The SEC Climate Disclosure Rule Abandoned, how the federal approach that preceded California’s law was withdrawn
The ESG Industrial Complex, the asset management pressure that shaped voluntary ESG disclosure before mandatory reporting arrived

Sources

California SB 253, Climate Corporate Data Accountability Act, signed October 7, 2023. Verified June 2026.
California Air Resources Board, Initial Implementing Regulations for SB 253 and SB 261, adopted March 2026. Verified June 2026.
PwC: “SB 253 and SB 261: California climate reporting explained.” Verified June 2026.
Morgan Lewis: “California Air Resources Board Approves Initial Regulations for Climate Disclosure Laws.” Verified June 2026.
Greenberg Traurig: “CARB Adopts Initial Climate Disclosure Reporting Regulations to Implement SB 253 and SB 261.” Verified June 2026.
Watershed: “A guide to California’s climate disclosure rules (SB 253, SB 261).” Verified June 2026.
California Air Resources Board bulletin, June 24, 2026, and CARB’s SB 253 program page. Read October 13, 2026.
Harvard Law School Forum on Corporate Governance: “CARB Publishes Preliminary List of Companies Potentially Subject to SB 253 and SB 261.” Read October 13, 2026.