Skip to main content

CARB Releases First-Year SB 253 Reporting Guidance

Published Date

On September 1, 2026, the California Air Resources Board (CARB) released its long-awaited guidance for the first reporting year under California's Climate Corporate Data Accountability Act (SB 253). The guidance provides important implementation details for entities preparing to submit Scope 1 and Scope 2 greenhouse gas (GHG) emissions data by the November 10, 2026 reporting deadline. Scope 3 emissions reporting is not required under SB 253 for the 2026 reporting year.

While many stakeholders were anticipating additional technical direction on GHG accounting methodologies, the guidance primarily focuses on facilitating first-year compliance and reducing reporting burdens during the program's initial implementation phase. 

Key Takeaways

  1.  CARB Continues to Exercise First-Year Enforcement Discretion

The guidance reconfirms CARB's previously announced enforcement approach for 2026. Reporting entities may submit Scope 1 and Scope 2 emissions data based on information they were already collecting as of December 5, 2024, regardless of whether the data has undergone limited assurance. This clarification reduces immediate compliance risk for organizations still maturing their emissions reporting programs and signals that CARB’s first-year priority is establishing participation rather than imposing strict data quality thresholds.

2.  Relief for Entities Not Collecting Emissions Data

One of the significant clarifications is CARB's confirmation that entities that were not collecting Scope 1 and Scope 2 emissions data and were not planning to collect such data as of December 5, 2024, are not expected to submit emissions data for the 2026 reporting cycle. Instead, CARB recommends that these entities submit a statement of non-reporting on company letterhead. At this time, CARB has not published a template for this submission.

3. Multiple Reporting Formats Accepted

For 2026, CARB is taking a flexible approach to report submissions and will accept a variety of reporting formats, including:

    • Existing sustainability or annual reports containing Scope 1 and Scope 2 emissions

    • Existing disclosures submitted to other reporting programs or voluntary initiatives

    • CARB's draft Scope 1 and Scope 2 reporting template

    • Statements of non-reporting, where applicable

For many organizations, this may significantly reduce first-year compliance costs and accelerate reporting readiness by allowing existing disclosure processes to serve multiple regulatory and voluntary reporting requirements.

4. Voluntary Reporting Platform Introduced

CARB has also launched a voluntary online intake platform to facilitate 2026 reporting ahead of the November 10, 2026 deadline. The platform can be used to:

    • Submit company contact information

    • Provide fee invoicing details

    • Submit Scope 1 and Scope 2 emissions data or the statement of non-reporting

Importantly, the guidance notes that use of the platform is voluntary, and companies may also submit data by sending an email here. 

The platform also includes optional fields for reporting Scope 1 and Scope 2 emissions data. These fields allow entities to disclose both location-based and market-based Scope 2 emissions, the global warming potential (GWP) assessment source used, indicate whether emissions data have been reported to other jurisdictions, and supply other supporting information. 

5. Assurance Requirement Deferred

Although SB 253 requires limited assurance beginning with 2026 disclosures, CARB confirms that it will accept submissions regardless of whether assurance has been obtained during the 2026 cycle. This additional flexibility may be particularly helpful for organizations that are still developing internal controls, documentation processes, and assurance readiness programs.

6. New Guidance on Scope 2 Emission Factors

The guidance also provides clarity regarding Scope 2 emission factor selection.

CARB states that no specific emission factor dataset is required for 2026 reporting. Companies may use EPA's most recent official eGRID release (eGRID 2023), the Cornerstone Sustainability Data Initiative's eGRID 2024 dataset, or other credible emission factor sources. CARB encourages entities to disclose the emissions factors and data sources used in their calculations.

What’s Still Unresolved?

While CARB’s guidance provides meaningful clarity on first-year compliance mechanics, many of the technical accounting questions companies have been waiting for remain unanswered. Organizations should recognize that the September guidance is focused primarily on reporting administration rather than establishing long-term methodological requirements.

At this time, CARB has not established requirements or provided additional direction regarding:

    • Global warming potential (GWP) assessment report alignment

    • Scope 2 market-based versus location-based accounting

    • Renewable electricity and energy attribute certificate treatment

    • Emission factor hierarchies

    • Restatement and recalculation requirements

    • Additional details regarding Scope 3 categories

As a result, companies should anticipate that reporting expectations and methodological requirements may continue to evolve through CARB's ongoing rulemaking process. Organizations with existing climate disclosure programs may wish to maintain detailed documentation of methodologies and assumptions to support future reporting adjustments if additional guidance is issued.

Preparing for 2027

CARB has indicated that these unresolved technical topics will be addressed through its ongoing rulemaking process for future reporting years.

The September 2026 guidance signals that CARB's primary objective is to encourage participation and establish a reporting baseline allowing organizations to familiarize themselves with California’s evolving climate disclosure framework. However, future reporting years are expected to introduce more detailed methodologies, data quality, and assurance expectations.

Actions Companies Can Take Now

Organizations can use the 2026 reporting cycle as an opportunity to assess and strengthen foundational elements of their greenhouse gas reporting programs, including:

    • Reviewing and documenting organizational boundaries and governance structures

    • Formalizing emissions calculation methodologies and supporting assumptions

    • Evaluating emission factor selection and documentation practices

    • Assessing Scope 2 accounting approaches and renewable electricity claim methodologies

    • Strengthening data management processes, controls, and audit trails

    • Preparing for future assurance requirements

    • Evaluating data availability and collection processes for future Scope 3 reporting obligations

Taking these steps now can help reduce future reporting adjustments, improve transparency, and support a smoother transition as California's disclosure requirements mature.

Looking Ahead

Perhaps the most important message from CARB's latest guidance is that the first reporting year is intended to drive participation and transparency, not perfection. For organizations that have delayed formalizing emissions reporting processes, 2026 provides a valuable opportunity to strengthen data governance, document methodologies, and identify gaps before reporting expectations become more prescriptive.

As CARB's rulemaking continues, companies should expect increased rigor around reporting methodologies, assurance, and Scope 3 disclosures. Organizations that use this year to improve the quality and consistency of their emissions data will be better prepared to navigate future requirements with confidence. Explore more about climate-related rulings and reporting regulations here.