California’s first corporate emissions filing is due November 10, 2026, and the regulation behind it is no longer a proposal. The Office of Administrative Law has approved CARB’s Initial Regulation — Title 17, California Code of Regulations, Article 6, sections 96070 through 96077 — and it took effect October 12. What gets filed by the deadline, though, is narrower and stranger than the headline version. For the first cycle, what you owe California depends less on what your emissions are than on what you were already doing about them on December 5, 2024.
This is the operator’s briefing: who is in the room, the three doors into the filing, the mechanics nobody reads until the week before, and the line between what is now in force and what CARB is still proposing.
First, decide whether you are in the room
SB 253 — the Climate Corporate Data Accountability Act, Health and Safety Code section 38532 — covers U.S. companies with total annual revenues over $1 billion that do business in California. “Revenue” is tested on gross receipts as California’s tax code defines them (Revenue and Taxation Code section 25120(f)(2)), using the lower of the two most recently completed fiscal years. “Doing business” borrows the tax code’s test as well: actively transacting in the state, or crossing its economic-presence thresholds on California sales, property, or payroll.
CARB’s guidance is blunt about whose job the determination is: yours. Entities are responsible for deciding whether they meet the definition of a reporting entity, including assessing their own revenue and California footprint. CARB has published a frequently-asked-questions document and sent reminder letters to organizations that may be subject to the program — if a letter arrived, treat it as a prompt to run the test, not as the test itself.
The statute behind the deadline carries penalties of up to $500,000 per reporting year for late filing, nonfiling, or other violations. The first cycle comes with a safety net, described below — but the net is CARB’s enforcement posture, not an amendment to the law.
Door one: you were already counting
CARB’s December 2024 Enforcement Notice set the line that still governs this cycle. For the 2026 report, CARB exercises enforcement discretion: you report the Scope 1 and Scope 2 emissions for your preceding fiscal year based on the information you already had, or were already collecting, when that notice was issued — whether or not the data received limited assurance.
The acceptable vehicles are deliberately unglamorous. CARB will take an existing annual report that includes your Scope 1 and Scope 2 data. It will take the data as reported to another program or voluntary initiative — the inventory already sitting in a CDP response or another filing does not need to be rebuilt in a California shape. Or you can use CARB’s Draft Scope 1 and 2 Reporting Template, posted in October 2025; its use is voluntary for this cycle.
Two details separate a filing from a number. Emissions are measured under the Greenhouse Gas Protocol, as the statute requires. And CARB encourages filers to include the context that qualifies the figures — methodologies, data sources, global warming potential values, organizational boundaries, disaggregation by category and gas, and the assumptions used. For Scope 2, no single emission-factor dataset is mandated: eGRID 2023 is acceptable, as are other credible sources, provided the report identifies the factors and where they came from.
Door two: you were not counting yet
If your company was not collecting Scope 1 and 2 data — and was not planning to — when the December 2024 notice issued, CARB does not expect an inventory for this first cycle. What it requests instead is a statement of non-reporting on company letterhead, saying exactly that, submitted before November 10 through the intake platform or by email.
Read that door carefully, because it is the one most often misdescribed. It is not an exemption from SB 253 and it is not a filing holiday. It is a one-cycle posture tied to a specific date: the discretion applies to the 2026 report only, and the facts it rests on — what you were collecting on December 5, 2024 — are either true of your company or they are not. Companies that were collecting data do not get to use the letter, and companies that use the letter should expect the posture to end with this cycle.
Assurance follows the same pattern of a hard statute and a soft first year. The law requires limited assurance on Scope 1 and 2 beginning in 2026, phasing to reasonable assurance by 2030. CARB will nonetheless accept 2026 submissions whether or not assurance has been obtained. The requirement did not move; the enforcement did.
The mechanics: platform, email, and a fee
CARB built a voluntary 2026 Report Intake Platform, released with its September 1, 2026 guidance document. Use is not mandatory. The platform collects contact information ahead of the deadline, offers fields to submit the Scope 1 and 2 report itself, and gathers billing information for fee invoicing. Anything the platform accepts can also be emailed to CARB’s climate disclosure inbox instead — the channel is your choice; the deadline is not.
The Initial Regulation also stands up the fee that funds the program: a flat annual charge per covered entity, set to cover CARB’s cost of administering it. Staff estimates during the rulemaking put the SB 253 fee in the low thousands of dollars per entity per year — roughly $3,100 — which is also why the intake platform asks for billing contacts. The fee is a rounding error next to the cost of building the inventory; the reason to register your contact information accurately is that this platform is how the program will reach you from here.
The road to this date is worth knowing, because it explains the compressed calendar. The regulation was proposed with an August 10, 2026 deadline. CARB withdrew the package in June, released modified text in July, and OAL approved the revised version in October — moving the first deadline to November 10 in the process. Companies that built their plan around August got three extra months; companies that waited for certainty got about four weeks.
What is in force, and what is still only proposed
In force today: the November 10, 2026 deadline for first-year Scope 1 and 2 reports; the definitions of revenue and doing business; the fee structure; and the enforcement-discretion posture for 2026 described above. Scope 3 reporting begins in 2027 under the statute — the emissions themselves are owed from next year, not from this filing.
Still to come: a second CARB rulemaking that will set the 2027-and-beyond machinery — accounting methodologies, deadlines, assurance requirements, and reporting formats. Anything you read about how 2027 reporting will work in detail is, at this point, a proposal moving through that process, not a rule you can file against. Build the 2026 filing to the documents that exist; design the underlying data system so it can absorb the machinery when it lands.
Do not conflate the companion law. SB 261, the climate-related financial risk act, covers a wider population (over $500 million in revenue), runs on a biennial cycle, and is currently not being enforced: the Ninth Circuit enjoined its enforcement in November 2025, and CARB has said it will not enforce the statute while the injunction stands. CARB opened a public docket in December 2025 where companies may post risk reports voluntarily. SB 261’s pause changes nothing about the November 10 SB 253 deadline.
If you also report in Europe
Dual reporters face two different instruments built on the same underlying inventory. California asks for an emissions number, measured under the GHG Protocol, from any company over the revenue line that does business in the state — regardless of where it is headquartered or listed. The EU’s CSRD, as narrowed by the Omnibus package, asks a wider question — double materiality across environmental and social topics, in ESRS format — of a differently drawn population. Our CSRD roadmap after the 2026 Omnibus walks the European side, and our regulatory convergence map tracks how the regimes line up.
The operational answer is boring and correct: one inventory, documented once, with the methodology trail kept at a standard that satisfies the strictest reader, then rendered into each regime’s format. Groups can report to California at the parent level, which keeps a multi-subsidiary structure from fragmenting into dozens of inconsistent filings. What does not transfer is the assurance clock and the legal posture — California’s good-faith first year is California’s alone.
For a facilities-level view of what the November 10 numbers set in motion inside buildings and portfolios, see our companion piece, November 10 Is Locked. The filing itself, though, is a three-week problem now: run the applicability test, establish which side of December 5, 2024 your company was on, and put the report — or the letter — through one of the doors before November 10.
Risk Coverage Hub, our sister desk, reads the same filing as an insurance document — what a signed emissions statement does inside a D&O application, a greenwashing defense, and a renewal.