California's Emissions Rule Took Effect With 29 Days to File

California's Office of Administrative Law approved the Air Resources Board's initial climate disclosure regulation on 12 October 2026, making it effective immediately and leaving covered companies 29 days to file. The regulation, codified at Title 17 of the California Code of Regulations, Article 6, sections 96070 to 96077, fixes 10 November 2026 as the first reporting deadline under Senate Bill 253. The law firms Farella Braun and Martel and Morgan Lewis both reported the approval, on 12 and 13 October respectively.

The obligation falls on US companies with annual revenue above $1 billion that do business in California. First-year reports cover Scope 1 and Scope 2 emissions, the direct emissions a company controls and the emissions from the energy it buys. Scope 3, the supply chain category that generates most of the argument, was deferred to 2027 and is the subject of a separate CARB rulemaking now under way. The board adopted an earlier version of the regulation on 26 February 2026, submitted a final package to the Office of Administrative Law on 20 May, withdrew it, and resubmitted on 21 September. The original filing deadline of 10 August was extended by three months along the way.

What a first report may legally contain

The deadline is firmer than what has to be filed by it. CARB's guidance document of 1 September 2026 sets out enforcement discretion for the first cycle, carried over from an enforcement notice the board issued in December 2024. Companies may report Scope 1 and Scope 2 emissions for their prior fiscal year using information they already held or were collecting on or before 5 December 2024. Companies that held no such data at that date are, in CARB's words, not expected to submit Scope 1 and 2 reporting data for this first reporting cycle in 2026 only. CARB instead asks them for a statement of non-reporting on company letterhead, and the guidance notes that several companies have already sent one.

Assurance follows the same pattern. Section 38532 of the Health and Safety Code requires limited assurance beginning in 2026, but CARB's guidance says it will accept submissions whether or not assurance has been obtained for this cycle. Reporting is mandatory. Verified reporting, in year one, is not.

A federal dataset that did not arrive

One passage in the guidance shows how much state reporting still leans on federal infrastructure. Companies generally calculate Scope 2 emissions using eGRID, the Emissions and Generation Resource Integrated Database maintained by the US Environmental Protection Agency. CARB records that the EPA has not released eGRID 2024 on its usual timeline. Reporting entities may therefore use the most recent official release, eGRID 2023, or an eGRID 2024 dataset published by the Cornerstone Sustainability Data Initiative, which generated it from the EPA's publicly available source code. California's first mandatory corporate emissions filings may rest in part on a federal dataset rebuilt by a third party because the agency that owns it did not publish.

The divergence is the point. As Parallax Nexus has reported, twenty-one states, the District of Columbia and three cities petitioned the DC Circuit on 1 October against the EPA's repeal of greenhouse gas limits for coal- and gas-fired power plants. Federal emissions rules are being withdrawn in the same season that the largest state-level corporate disclosure regime becomes enforceable.

SB 253's companion law has not been so lucky. The US Court of Appeals for the Ninth Circuit has enjoined enforcement of Senate Bill 261, the climate-related financial risk disclosure statute, pending appeal, and CARB has said it will not enforce it while the injunction remains in effect. The injunction does not reach SB 253, and the 12 October approval did not change that.

The honest reading is that 10 November will produce a filing list rather than an emissions dataset. A regime whose first year accepts unassured numbers, pre-2024 data and letters explaining an absence of data will reveal who is in scope before it reveals what anyone emits. What is not known is how many covered companies will take the non-reporting route, because CARB has published no running count, and whether the Ninth Circuit's reasoning on SB 261 eventually reaches SB 253 on appeal.