What is California SB 253 and what does it mean for UK suppliers?

## What is California SB 253? The **Climate Corporate Data Accountability Act** — known as SB 253 — is a California state law that requires large companies doing business in California to publicly disclose their greenhouse gas (GHG) emissions. Signed into law in October 2023, it is one of the most ambitious climate disclosure laws in the world, and it affects companies far beyond California's borders. The law is administered by the **California Air Resources Board (CARB)**, which is developing the implementing regulations. CARB published proposed initial regulation materials in December 2025, including a proposed first-year reporting deadline of **10 August 2026** for Scope 1 and 2 emissions. ## Who does SB 253 apply to? SB 253 directly applies to: - **Any US public or private company** that does business in California and has **total annual global revenues exceeding $1 billion** - This includes companies incorporated outside California — if you do business in California, you are in scope - It does **not** directly apply to foreign (non-US) companies, but see below for why it still affects UK suppliers The thresholds are based on total global revenue, not California revenue. A company with $1.1 billion in global revenue and $10 million in California sales is fully in scope. ## What emissions must be disclosed? SB 253 requires disclosure of all three scopes of GHG emissions: - **Scope 1:** Direct emissions from owned or controlled sources (e.g. company vehicles, on-site combustion) - **Scope 2:** Indirect emissions from purchased electricity, heat, or steam - **Scope 3:** All other indirect emissions across the value chain — including emissions from purchased goods and services (Category 1), which is where your business comes in **Reporting timeline (as proposed by CARB):** - **Scope 1 and 2:** First report due **10 August 2026** (covering FY2025 data) - **Scope 3:** Required from 2027 (covering FY2026 data) - **Third-party assurance:** Limited assurance for Scope 1 and 2 from 2026; reasonable assurance required by 2030 ## Why does SB 253 affect UK suppliers? Scope 3 Category 1 — purchased goods and services — is typically the **largest component** of a large company's carbon footprint, often accounting for 70–80% of total emissions. When a company subject to SB 253 reports its Scope 3 emissions, it needs emissions data from its suppliers. This means if you supply goods or services to a company with over $1 billion in global revenue that does business in California, you should expect: 1. **Supplier emissions questionnaires.** Your US customers will ask for your Scope 1 and 2 emissions data, and eventually your Scope 3 data, to complete their own SB 253 reports. 2. **Supplier codes of conduct.** Many large companies are updating their supplier agreements to include climate disclosure requirements aligned with SB 253. 3. **Preferred supplier status.** Companies that can provide verified emissions data quickly will be preferred over those that cannot. This is becoming a commercial differentiator. 4. **Contract risk.** If you cannot provide emissions data, your customer may need to estimate it — or may look for suppliers who can provide it. ## What about SB 261? **SB 261** (the Climate-Related Financial Risk Act) is a companion law requiring companies with over $500 million in revenue doing business in California to prepare a climate-related financial risk report aligned with TCFD. However, a Ninth Circuit court injunction issued in November 2025 has paused enforcement. CARB has stated it will not enforce the January 2026 deadline while the appeal is pending. SB 261 does not directly require supply chain data, but it increases the pressure on large companies to understand and manage their climate-related supply chain risks. ## What should UK suppliers do now? **Immediately:** - Identify which of your US customers are in scope (over $1B global revenue, doing business in California). These companies will need your emissions data for their August 2026 Scope 1 and 2 reports. - Review any supplier questionnaires you have already received from US customers — many will already reference SB 253 or GHG Protocol requirements. **By end of 2025:** - Calculate your **Scope 1 and 2 emissions** using FY2025 data. This is the minimum data your SB 253-subject customers will need for their first reports. - Document your calculation methodology. CARB requires third-party assurance, so your customers' auditors may ask how you calculated your numbers. **2026–2027:** - Prepare **Scope 3 data**. If you supply to SB 253-subject companies, they will need your full emissions data for their Scope 3 Category 1 reporting from 2027. - Consider third-party verification of your own emissions data. Verified data is more credible and reduces the risk of your customers' auditors questioning your figures. **Monitor:** - Track CARB's rulemaking progress. Final regulations may not be published until late 2026. Monitor the CARB website for updates on the SB 261 court injunction and revised enforcement dates. ## How SolvingESG helps SolvingESG gives UK SMEs a structured way to respond to SB 253 supplier questionnaires. Our platform helps you: - Calculate your Scope 1, 2, and 3 emissions using the GHG Protocol methodology your US customers expect - Generate a supplier emissions report you can share with your US customers - Track your progress against the frameworks your customers care about - Store your calculation methodology and supporting evidence in one place, ready for audit [Read our full USA jurisdiction guide →](/guides/usa) --- *Disclaimer: This article is for general information purposes only and does not constitute legal advice. If you have specific concerns about your SB 253 obligations, please consult a qualified legal adviser.*