California's First Climate Reports Are Due November 10. The Grace Period Ends There

Six weeks from now, California's corporate climate disclosure law stops being a compliance project and becomes a public record. The first reports under SB 253 are due November 10, and the California Air Resources Board has spent September making that first filing as easy as it could reasonably be. Assurance is optional. Old data is acceptable. Companies with nothing to report can say so on letterhead. That generosity is real, and it is also the reason so many companies risk misreading what comes next. The guidance covers one cycle, and every filing made under it will be visible to investors, customers and activists long after the lenient rules have expired.

What CARB Is Asking For This Year

The law reaches further than many companies assume. It applies to entities that do business in California and have more than $1 billion in total annual revenue, public or private, wherever they are incorporated, according to Sweep's review of the early September guidance. Proskauer notes that CARB measures the revenue threshold by the lesser of an entity's two previous fiscal years of revenue, so a single strong year does not trigger coverage on its own. Obsidian Regulatory Intelligence points to Apple, Chevron, Alphabet and Walmart as examples of the companies in scope.

The dividing line is a date. CARB's enforcement notice of December 5, 2024 splits covered companies into two groups, as Donnelley Financial Solutions lays out. Companies that were already collecting emissions data submit scope 1 and 2 figures, with or without limited assurance. Companies that were not file a statement of non-reporting on company letterhead by November 10. Neither path permits doing nothing. Filers can submit an existing annual report that already contains the figures, data they reported to another regulatory program or voluntary initiative, or CARB's draft template, which remains voluntary. CARB will also not require a single emissions factor dataset this year: EPA's eGRID 2023, eGRID 2024 or other credible sources are all acceptable.

Reports can go through a voluntary intake platform on CARB's ArcGIS portal or by email. The platform asks for more than the guidance might suggest. As a Mondaq analysis of the intake form details, it requests the full legal name as filed on tax forms, a federal EIN, California Corporation Number or Secretary of State file number, and the California Principal Business Activity code from the company's state tax filing, entity by entity. Groups with many subsidiaries should expect the entity mapping to take longer than the emissions math.

The Parts of the Filing That Do Not Go Away

Three features of this first cycle are permanent, and they matter more than the flexibility. The first is publicity. Uploaded emissions reports and statements of non-reporting will be made public, and CARB tells filers not to include confidential business information. A letterhead statement saying a billion-dollar company was not measuring its own emissions in late 2024 is a document that will be quoted back.

The second is cost. All covered entities will be assessed a fee regardless of whether they submit emissions data or a non-reporting statement. Invoices go out on or before December 10, 2026, with payment due within 60 calendar days, and Sweep notes the fee is adjustable by the California Consumer Price Index. The third is enforcement. CARB has said it will exercise enforcement discretion in the first cycle, but civil penalties for non-filing and late filing reach up to $500,000 a year, and Obsidian stresses that the penalty accrues for each year of non-compliance rather than as a one-off fine.

The legal picture is also sharper than headlines suggest. The Ninth Circuit injunction pauses only SB 261, the companion climate-related financial risk law, not SB 253, so the November deadline stands. CARB approved its Initial Regulation on February 26, 2026 and withdrew it on June 24 for clarifying changes, which is part of why companies are reading guidance documents rather than final rules six weeks out.

Why 2027 Is the Real Deadline

The flexibility has an expiry date written into it. DFIN quotes the guidance directly: it applies only to the 2026 reporting cycle, and requirements for 2027 and beyond are being developed through a second rulemaking. Under Obsidian's timeline, scope 3 reporting and limited assurance both begin in 2027, with reasonable assurance required from 2030. According to GSI Environmental, CARB has proposed requiring the five most commonly reported scope 3 categories from 2027: purchased goods and services, fuel and energy related activities, waste, business travel and employee commuting. Nothing in the guidance carries the letterhead option past this cycle, which is the detail that should worry those filers most. They face their first emissions inventory and their first value chain disclosure in the same year.

That is the trap in the easy first year. A company that files an old sustainability report this November and treats the job as done will enter 2027 needing assured scope 1 and 2 figures, a first scope 3 inventory built on supplier data it has never requested, and processes that can survive an auditor, all under rules that do not exist yet. The companies that use the next six weeks well will treat November as a dry run for that year, not as the finish line.

The SB 253 Filing Playbook

• Confirm which path you are on: Decide, and document why, whether you were collecting scope 1 and 2 data as of December 5, 2024. That answer determines whether you file numbers or a letterhead statement.
• Map every covered entity now: Gather legal names as filed on tax forms, EINs or California identifiers, and Principal Business Activity codes for each entity before the intake form asks for them.
• Write for a public audience: Assume every filing will be read by investors and critics. Strip confidential business information and make sure the numbers match what you have published elsewhere.
• Record your methods even though CARB does not require it: Note which emission factors you used, eGRID 2023, eGRID 2024 or another source, and why. That file becomes the starting point for 2027 assurance.
• Start the scope 3 supplier conversation this quarter: Scope 3 reporting begins in 2027. Identify the highest-emitting categories and the suppliers whose data you will need, and ask for it early.
• Budget for fees and assurance together: Plan for a CARB invoice by December 10 and for limited assurance engagements from 2027, and assign someone to track the second rulemaking as it develops.