California climate disclosure laws: Everything companies need to know

Updated May 2026

CARB adopted its initial implementing regulation on February 26, 2026—confirming fees, key definitions, and the first reporting deadline. Companies with more than $1 billion in revenue now have until August 10, 2026 to file scope 1 and 2 emissions under SB 253, with scope 3 and assurance requirements following in 2027.

Meanwhile, SB 261 climate-risk reporting remains pending a Ninth Circuit ruling, and a second CARB rulemaking is underway that will shape what 2027 filings look like. For the roughly 2,600 companies in scope for SB 253 and 4,100 for SB 261, the picture is getting clearer—but the details matter.

This whitepaper breaks down both laws, tracks the latest regulatory developments, and walks through what companies need to do now.

What's inside:

• Deadlines and fees, confirmed. The full timeline from the first SB 253 filing on August 10, 2026 through scope 3 and reasonable assurance requirements in 2030—plus CARB's newly finalized filing fees.
• Who's in scope—and why it's broader than you think. Revenue thresholds, the "doing business" test, and new CARB guidance on how corporate groups filing as unitary businesses should aggregate revenues.
• What to file and how. A breakdown of reporting requirements for both laws, CARB's draft template, accepted assurance standards, and what "good-faith effort" means in year one.
• Where litigation stands. The latest on the Ninth Circuit challenge, what's stayed, what's not, and what it means for your SB 261 timeline.

How Watershed helps. AI-accelerated reporting, audit-ready emissions measurement, and expert guidance from policy and assurance specialists—all in one platform.