California SB 253: What the 2026 Enforcement Update Means for Your Business

California's SB 253 requires companies doing business in the state with annual revenues over $1 billion to report prior-year Scope 1 and Scope 2 greenhouse gas emissions. The first filing deadline is August 10, 2026, using an Excel emissions template accompanied by a limited assurance report from a CPA firm or a qualifying third party. To fund the program, CARB will assess revenue-based fees, with 2026 fees to be determined on or before September 10, 2026.

The SB 253 law remains in effect. What has changed is how CARB intends to enforce it during this inaugural cycle.

What CARB announced

At the March 24, 2026 SB 253 public workshop, CARB stated it will exercise enforcement discretion for the first reporting cycle — provided companies demonstrate good-faith efforts to comply. In practical terms, this means no enforcement action will be taken if the Excel emissions template and limited assurance report are not submitted with the August 10 filing.y post content

CARB's relaxed enforcement is designed to support companies actively working toward full compliance in 2027. It's not an excuse for inaction.

2026 vs. 2027 at a glance

The table below shows current requirements alongside CARB's proposed 2027 standards.

Requirement

Set organizational boundary

Classify Scope 1 & 2 emissions

Classify Scope 3 emissions

Calculate emissions

Obtain limited assurance (Scopes 1 & 2)

Report to CARB

2026

Best efforts

Best efforts

Not required

Best efforts

Not required

Required

2027

Required

Required

Proposed

Required

Required

Required

The biggest unknown: limited assurance

For most companies that have already been calculating emissions, the limited assurance review — required starting in 2027 is the least familiar piece of the puzzle. The assurance report must be signed by an independent CPA firm or other qualifying third party following AICPA-established procedures.

Many companies are getting ahead of this by hiring consultants to perform a readiness assessment: a structured process in which a consultant applies limited assurance review procedures, evaluates documentation and underlying assumptions, and provides best-practice guidance. Because the consultant is not independent, they can give hands-on advice, something an auditing CPA firm cannot do during the actual engagement.

The result is a set of "tick and tie" workpapers that give the 2027 CPA firm a clean starting point. This typically reduces both the cost of the independent assurance engagement and the internal staff time needed to support it.

Get ahead of 2027

Is your company ready for full SB 253 compliance?

A readiness assessment now can save significant time and cost when the 2027 independent assurance requirement kicks in. Let's talk about where you stand.

About ESG Administration

ESG Administration provides companies required to report under SB 253 with the resources and expertise to meet CARB's requirements with a focus on minimizing the internal burden on your team. To learn more about ESG Administration contact Joe Holman at joe.holman@esgadmin.com