CA Senate Bill 253 Assurance Review
Independent Assurance, Collaborative Work
Assurance success comes when the work is collaborative, clear, and on time. The right verifier surfaces issues early, keeps timelines on track, and evaluates whether disclosures are complete and well supported.
EcoCira provides limited and reasonable assurance for SB-253 as an accredited verification body under CARB’s GHG and LCFS programs. We stay aligned with regulatory requirements — no unnecessary work, no standards beyond what the rule requires. The result is transparent assurance that gives teams confidence in their reporting.
You can find answers to all your assurance-related questions below and feel free to reach out to us at services@ecocira.com for any additional inquiries.
Navigating Assurance Reviews
SB 253 assurance requirements can be overwhelming, especially for organizations new to verification. Use this guide to learn what to expect, clarify requirements, and ensure the process is organized and manageable.
The sections below walk through the general steps of an assurance review and outline the key differences between limited and reasonable assurance.
- 1. Planning &
Scope - 2. Data
Collection - 3. Testing &
Verification - 4. Site
Visit - 5. Findings &
Correction - 6. Final
Opinion - New Tab
Planning & Scope
The assurance reviewer meets with your team to understand operations, reporting boundaries, methodologies, and key data sources.
- Kick-off meeting to review boundaries, sources, and reporting methodologies
- Identification of high-risk emissions categories (Scopes 1, 2, & 3)
- Agreement on timelines, deliverables, and sampling approach
Data Collection
Expect requests for activity data, emission factors, calculations, internal controls, and prior-year reports.
- Assurance provider issues a document request list (activity data, meters, invoices, utility bills, models, etc.)
- Collection of calculation workbooks, emission factors, and supporting documentation
- Review of organizational controls, roles, and data management systems
Testing & Verification
Auditor teams trace reported values back to source documents, sample high-risk or high-emission categories, and check reasonableness.
- Recalculation of emissions data for selected high-risk categories
- Evaluation of internal controls for data accuracy and completeness
- Interviews with personnel involved in data collection and reporting
Site Visit
Assurance reviewers may make site visits, interviewing staff responsible for data entry, metering, procurement, and sustainability reporting.
- On-site meter checks, equipment verification, or activity data confirmation
- Walkthroughs of data systems and operational processes
- Live data pulls from database systems
- Photographic or logged evidence collection using CARB-style protocols
Findings & Correction
Assurance reviewers provide issues, discrepancies, and required corrections before issuing an assurance opinion.
- Issuance of preliminary log of issues to fix
- Opportunities to correct or clarify data before the final opinion
- Materiality thresholds applied depending on assurance level
Final Opinion
A formal report is issued stating whether disclosures are free from material misstatement under the chosen standard.
- Summary of testing performed and confidence level
- Documentation suitable for CARB and SB 253 public reporting
Limited Assurance
Limited assurance provides a lower level of confidence in the accuracy of reported data through limited review and analytical procedures.
- Relies primarily on interviews, document reviews, and high-level analytical checks
- Generally conducted virtually
- Lower cost and effort, and typically used for voluntary emissions disclosures
Reasonable Assurance
Reasonable assurance provides a higher level of confidence in the completeness and accuracy of GHG disclosures through detailed testing, sampling, and procedures.
- Includes more rigorous data testing, sampling, control evaluation, and on-site visits
- Requires deeper, facility-level assessment and traceability checks
- Higher cost and effort than limited assurance
CARB Compliance is Our Core Business
Our approach is straightforward: independence and rigor, paired with open communication and constructive feedback, so teams can stay focused on running the business.
We work with CARB regulatory programs everyday, ensuring some of the largest Fortune-500 refining and manufacturing companies comply.
EcoCira is an accredited third-party verifier for CARB Greenhouse Gas and LCFS reporting programs—the same foundation upon which SB 253 reporting is built. Reach out, we can guide you through this process.
Qualified Engineers with Proven Regulatory Knowledge
We lead with engineering. Our team’s technical foundation allows us to look past simple data checks and deeply evaluate your processes, emissions sources, and monitoring systems. Process-level insight helps prevent inaccuracies throughout the value chain and ensures your verification is precise, reliable, and audit-ready.
Personalized Attention From a Team Dedicated to Your Success
Our size lets us stay hands-on and deeply engaged. A strong assurance partner works collaboratively, communicates clearly, and surfaces issues early so nothing becomes a surprise late in the process. We communicate early and often, maintain transparent issue logs, and are always available to address questions or concerns as they arise.
Over 20 Years of Regulatory and Emission Reporting Expertise
EcoCira is accredited under CARB GHG and LCFS, Oregon DEQ, and Washington State GHG programs. Our team has supported and verified some of the world’s leading Fortune-500 refiners and manufacturers, applying CARB’s rigorous standards across large, multi-facility operations. We bring unmatched versatility and industry insight to every engagement.