California’s Climate Corporate Data Accountability Act (SB 253) requires qualifying public and private companies doing business in California to report their greenhouse gas emissions annually. Reporting begins with Scope 1 and Scope 2 emissions in 2026, followed by Scope 3 emissions across the value chain in 2027.
For companies preparing their first disclosure, much of the work involves bringing together information from different parts of the business. Facilities teams may hold utility and fuel records, finance may maintain purchasing data, and procurement may manage supplier information. Clear responsibilities and consistent calculation methods help turn those records into an emissions inventory that the company can review and explain.
CARB identifies November 10, 2026 as the first Scope 1 and Scope 2 reporting deadline. Its September reporting guidance provides flexibility for the first reporting cycle, including accepting submissions with or without limited assurance. The guidance describes the initial regulation as subject to Office of Administrative Law approval, while CARB develops the requirements for 2027 and beyond through separate rulemaking.
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Preparing Your First SB 253 Report: A Checklist
A clear reporting process helps teams work toward the same deadline and leaves time to resolve questions before submission. The eight steps below follow that process, from confirming which requirements apply to your company through collecting data, reviewing calculations, and filing the report. They also explain how CARB’s first-year flexibility affects preparation and where to begin planning for future reporting cycles.
1. Understand the requirements and deadlines
SB 253 applies to qualifying U.S.-formed companies with more than $1 billion in annual revenue that do business in California, including private companies. The law permits consolidated reporting at the parent level. Reporting timelines are currently as follows:
- November 10, 2026: First Scope 1 and Scope 2 reporting deadline identified by CARB.
- By December 10, 2026: CARB to issue fee notices under the initial regulation, subject to OAL approval. Payment is due within 60 days of the notice date.
- 2027: Scope 3 reporting begins under the statute. CARB has proposed limited assurance for Scope 1 and Scope 2 beginning in 2027; detailed requirements are still under development and subject to additional rulemaking.
Finance and legal should confirm applicability using CARB’s initial regulatory text, which assesses entity-level revenue using the lower of the two preceding fiscal years. Its definitions of revenue, doing business in California, and exclusions determine which entities qualify.
The text also sets the reporting period. For 2026 submissions, fiscal years ending on or before February 1 use the year ending in 2026. Those ending later use the year ending in 2025, with an option to use a more recent completed fiscal year if data is available. A calendar-year company would therefore use 2025 data; a company with a January 31 year-end would use the fiscal year ending January 31, 2026.
The law provides for annual fees and penalties of up to $500,000 per reporting year, with good-faith efforts among the enforcement considerations.
2. Identify what data you need and where to find it
A useful starting point is a map of the data your inventory needs, who holds it, and whether it covers the full reporting period.
- Scope 1: Direct emissions from owned or controlled sources, such as boilers, furnaces, and company vehicles. Facilities, operations, and fleet teams often hold these records.
- Scope 2: Indirect emissions from purchased electricity, steam, heating, and cooling. Utility bills and energy procurement records are common sources.
- Scope 3: Indirect emissions across the value chain, including purchased goods, transportation, waste, and the use of sold products. Identifying the relevant activities now will help you prepare for 2027.
Give each data request an owner and due date. Asking owners to flag missing months or unavailable records with their initial response leaves more time to resolve gaps before review.
3. Form a cross-functional working group
A reporting lead can coordinate the process, but several teams will need to contribute. Typical responsibilities include:
- Sustainability: Defines the inventory approach and coordinates emissions calculations.
- Legal and compliance: Reviews applicability, requirements, and disclosure decisions.
- Finance: Provides financial and spend data and validates organizational information.
- Procurement: Supplies purchasing records and coordinates supplier information for Scope 3.
- Operations: Provides activity data for facilities, equipment, and vehicles.
- IT: Supports data access, systems, and security.
Agree on collection, review, and approval dates together. Teams supplying records need to understand the time required for calculations and follow-up questions after their files arrive.
4. Establish a centralized data management system
Keeping source records, calculations, and review decisions in one system makes the inventory easier to manage and check. A carbon accounting platform can support this work as collection expands across locations and emissions categories.
Your system should:
- Store data consistently across facilities, business units, and geographies.
- Record calculation methods, emission factors, and assumptions.
- Preserve source documents and changes to the data.
- Accommodate additional Scope 3 information.
A reviewer should be able to trace a reported figure to its source and understand any adjustments without reconstructing the calculation from email exchanges.
5. Gather data and calculate your carbon footprint
Start with available utility bills, energy invoices, and fleet fuel records. Comparing the files received against your facility and asset lists will help identify missing sources before you calculate totals.
As you calculate:
- Define boundaries. Document your consolidation approach and the operations it covers. This is separate from determining which legal entities must report. SB 253 calls for GHG Protocol reporting covering worldwide operations within the reporting boundary.
- Use appropriate emission factors. CARB’s 2026 guidance permits eGRID 2023 or another identified credible source for Scope 2 factors.
- Document assumptions. Explain estimates, extrapolations, and proxies so reviewers can understand how you addressed missing information.
- Check results. Investigate duplicates, inconsistent units, missing periods, and unusual changes before approving totals.
Under CARB’s December 2024 enforcement notice, first-year reports may disclose prior-fiscal-year emissions using information companies possessed or were collecting as of December 5, 2024. This flexibility depends on good-faith efforts to comply. CARB will not take enforcement action for incomplete reporting where companies make a good-faith effort to retain all relevant emissions data for that fiscal year. Keep a record of unresolved gaps and your efforts to address them.
6. Plan for assurance
The statute calls for limited assurance of Scope 1 and Scope 2 emissions beginning in 2026. Under its first-year guidance, CARB will accept 2026 submissions with or without limited assurance. That flexibility applies to this reporting cycle.
Your company may already have an assurance engagement or need assurance for another commitment. Confirm the scope and timing with your provider, and prepare documentation of data sources, calculation methods, assumptions, and internal reviews. Those records also support internal approval and preparation for future assurance requirements.
7. Submit your report
For 2026, CARB accepts existing annual reports containing Scope 1 and Scope 2 emissions, existing Scope 1 and Scope 2 data reported to other programs, or its voluntary template. Its submission instructions provide an optional intake platform and an email route at climatedisclosure@arb.ca.gov.
A separate first-year provision concerns companies without existing Scope 1 or Scope 2 information that were not collecting relevant data as of December 5, 2024. The September guidance recommends a company-letterhead statement explaining that the company was neither collecting nor planning to collect the data when the notice was issued. Legal should review eligibility against the initial text and guidance; incomplete records alone do not establish eligibility.
Before filing, check that the report identifies the company and period and matches the approved inventory. Retain the approved report and submission evidence, and brief your communications team on questions the disclosure may prompt.
8. Review your process and plan ahead
After submission, review the process with the teams involved:
- Where did bottlenecks occur?
- Which data was difficult to obtain or incomplete?
- Which processes could be automated or made more consistent?
CARB’s July 2026 staff proposal would initially require five Scope 3 categories: purchased goods and services (Category 1), fuel- and energy-related activities (3), waste generated in operations (5), business travel (6), and employee commuting (7). The other ten categories would remain voluntary. These category requirements and the proposed 2027 assurance timing remain proposals.
Begin identifying Scope 3 data sources and discussing requests with procurement and other owners. Assign responsibility for the gaps identified in your first inventory, and monitor CARB’s rulemaking as requirements for the next cycle take shape.
