SB 253: The Climate Corporate Data Accountability Act
We passed the law. Now CARB must make it count.
SB 253 (Wiener, 2023) is the California law that requires America’s largest companies to publicly report their full climate pollution, from smokestack to supply chain. EnviroVoters co-sponsored it in 2023. Now the California Air Resources Board (CARB) is writing rules to implement the law, and corporate polluters are pressuring them to keep the biggest pollution sources hidden.
Key dates coming up:
| Date | What happens |
|---|---|
| First reports due from companies on their Scope 1 and Scope 2 emissions. |
At a glance:
| Number | What it means |
|---|---|
| 2,000+ | of the country's largest companies required to report emissions data |
| 80%+ | of the average company's carbon footprint is "Scope 3," the emissions from its supply chain and products |
| 5 of 15 | Scope 3 categories CARB's draft would require, with no date for the rest |
| $0 cost | to taxpayers, because the law requires company fees to cover the full cost of the program |
What does SB 253 do?
You can’t cut the pollution you can’t see.
SB 253 is a California law, written by Senator Scott Wiener and sponsored by California Environmental Voters, that became law in 2023. This law makes the wealthiest US companies doing business in California publicly report all of their greenhouse gas pollution every year. That data goes on a public platform, where anyone can search and download the emissions reports. SB 253 does not create restrictions or limits on emissions. Instead, it functions as a corporate transparency measure to give the public information on how much greenhouse gas pollution the largest corporations are creating.
Who: US-based public and private companies with more than $1 billion in annual revenue that do business in California. Roughly 2,600 of the country’s largest corporations fall under this category.
What: The law requires transparent disclosure of all emission types, including Scope 1 (direct emissions), Scope 2 (purchased energy), and Scope 3 (supply chain and product use). These are reported annually and verified by an independent auditor.
When: The first Scope 1 and 2 reports are due on November 10, 2026. Scope 3 reporting begins in 2027.
How: Reporting follows the global Greenhouse Gas Protocol, the same standard most big companies already use for international reporting in places like the European Union. Nearly 90% of S&P 500 companies already report Scopes 1–2; about 70% report Scope 3.
Why does SB 253 matter?
Effective. Zero cost to taxpayers. Already the global norm.
Disclosure drives real cuts. Measurement changes behavior. After the EPA began requiring power plants to report their emissions, the largest plants cut their carbon emission rates by about 7%, and 10% at plants owned by public companies, with no reduction mandate at all.
Affordable climate policy. At a time when climate is being pitted against affordability, SB 253 costs taxpayers nothing: annual filing fees of about $3,100 per company fund the program. For billion-dollar firms, compliance is a rounding error.
Protects Californians’ savings. Emissions are a risk signal for the pensions and 401(k)s Californians depend on. Vanguard has urged the SEC to keep standardized emissions disclosure, and Apple, Google, Microsoft, Salesforce, and IKEA backed SB 253.
The world already does this. The EU, UK, Japan, Australia, and Singapore require emissions reporting, about 40 countries covering most of global GDP. If a company isn’t reporting in California, it’s almost certainly reporting somewhere else.
What is CARB deciding about SB 253?
Right now, CARB is working to finalize their reporting requirements for corporations under SB 253. They are considering a proposal that would scale back what companies are required to report, cutting down on the critical climate transparency that the law gives.
The new proposal to limit what emissions need to be reported has several problems:
The law requires full value-chain reporting. Scope 3 can make up 70 to 90% of a company’s emissions. CARB staff now propose requiring just five of the fifteen Scope 3 categories, and haven’t said when, or whether, the other 10 will ever be required. This has changed since CARB’s March 23, 2026 workshop. In March, CARB was considering implementing the law as intended by requiring all fifteen Scope 3 categories, without piecing them apart. Other countries that require Scope 3 emissions reporting require all fifteen categories without breaking them up in this way.
It tilts the playing field. Food, apparel, and agriculture would report most of their footprint. Oil and gas would skip the emissions from the fuel they sell, and banks the emissions they finance, their biggest sources by far.
It leaves companies guessing. With no end date for the phase-in, businesses can’t plan. They need to know when full reporting is coming so they build their systems and prepare.
It breaks the law’s promise. Consumers, investors, and lawmakers were promised the whole picture. Partial data on the wrong categories delivers neither transparency nor accountability for the public.
Our ask to CARB:
Require every material Scope 3 category. If there is a phase-in, put a firm sunset date on it, so every sector reports on the same terms.
How did SB 253 become law and where does it stand now?
EnviroVoters co-sponsored and led the campaign for corporate climate disclosure, which ended with the passing of SB 253, from its first introduction until it was signed into law. You can read the full story of our work on the SB 253 campaign here.
| Date | Milestone |
|---|---|
| Governor Newsom signs SB 253, the first US law requiring full value-chain emissions reporting. | |
| In the US Chamber of Commerce's lawsuit, the Ninth Circuit pauses companion law SB 261 but lets SB 253 move forward. | |
| CARB adopts its first rules, setting who's covered, fees, and the first deadline. | |
| CARB amends the first rule to push the first reporting deadline to November 10. | |
| CARB staff propose limiting required Scope 3 reporting to 5 of 15 categories. | |
| Late 2026 | CARB is writing the rules for 2027 and beyond, with a Board vote expected by year's end. |
Learn more about SB 253
Resources and further reading
CARB is Proposing Watered Down Corporate Emissions Disclosure Rule – Americans for Financial Reform
Why Double Counting is so Misunderstood – Persefoni
The State of Corporate Sustainability Disclosure 2025 — UCLA IoES
Vanguard backs US climate reporting standards in SEC response
Former CARB Chair Mary Nichols and former legislator Fran Pavley (2023) on SB 253
California Environmental Voters public comment to CARB board
FAQ
Does SB 253 double count emissions?
Not in a way that matters. One ton of pollution can appear in two companies’ reports, the oil company that sold the fuel and the trucking company that burned it, because each report shows that company’s own exposure. Nobody adds the reports together as a national total.
Is SB 253 delayed?
The first deadline moved three months, to November 10, 2026. Supply-chain reporting still starts in 2027.
Does SB 253 apply to small businesses?
No. Only U.S. companies with more than $1 billion in annual revenue that do business in California are required to report emissions under SB 253.
What’s the difference between SB 253 and SB 261?
SB 253 requires companies to report their emissions. SB 261 requires reports on climate-related financial risks; a federal court has paused it while a lawsuit continues.
Is SB 253 being challenged in court?
Yes. Business groups led by the U.S. Chamber of Commerce sued in 2024. The courts have let SB 253 take effect while the case continues.