Verification of GHG Emissions Data Reports

This page last modified November 14, 2017

The Regulation for the Mandatory Reporting of Greenhouse Gas Emissions (reporting regulation or MRR) requires the independent verification of greenhouse gas (GHG) emissions data reports.   Verification questions may be sent to  
Information about the Offset Verification Program is provided at:

MRR Regulation (with referenced version of U.S. EPA's 40 CFR Part 98)

Cap-and-Trade Regulation


The reporting regulation was developed under the California Global Warming Solutions Act of 2006 (Statutes of 2006; Chapter 488; Health and Safety Code sections 38500 et seq.) and approved by the California Air Resources Board (ARB or Board) in December 2007, with subsequent amendments in 2010, 2012, 2013, and 2014.  The 2014 MRR revisions became effective on January 1, 2015.  The requirements for independent verification of emissions data reports and ARB oversight of accreditation were included in the original regulation and are consistent with international best practices.  The MRR is codified in Subchapter 10, Article 2, sections 95100 to 95158, title 17, California Code of Regulations.

Accreditation and Oversight

ARB has established and implemented a verification program to support mandatory GHG reporting. Two primary components are an accreditation program for GHG verification bodies and individual verifiers and a verifier performance oversight program. ARB is responsible for evaluating the verification services provided by ARB-accredited verification bodies and verifiers to ensure California's high quality standards are achieved.

Only ARB-accredited verification bodies may provide verification services to reporting entities. The following web link provides a list of ARB-accredited verification bodies. Additional accredited individuals listed in the second link may participate on verification teams as subcontractors  to accredited verification bodies. The third-party verification requirements, threshold, and deadline are specified in section 95103(f) of the reporting regulation.

List of Accredited Verification Bodies and Executive Orders
List of Accredited Individual Verifiers  
Executive Orders for Individual Verifiers (updated July 31, 2017)

Accreditation Fact Sheet
More about Verification and Audits

Verifier Accreditation Training

If you are interested in becoming an accredited verifier, adding addtitional sector accreditation, or pursuing accreditation as a new verification body, please send an email to
Training for new candidates, and existing verifiers seeking an additional sector accreditation, was last provided on March 2-6, 2015, in Sacramento.  Accreditation training via webinar for existing accredited verifiers was provided on March 17, 2015.

Frequently Asked Questions regarding accreditation training

Information for Verifiers

Questions regarding ARB accreditation and verification should be sent to
Verification Body Application for Accreditation/Reaccreditation
Application for Verifier Reaccreditation (an application must be submitted for existing accredited verifiers every 3 years)
Application for New Verifier Accreditation Training
Conflict of Interest (COI/NOVS) Form
Verification Statement Form (for use with all reporting entities except petroleum refineries)
Petroleum Refinery Verification Statement Form (for use with petroleum refineries only)

Information for Reporting Entities

Reporting entities are required to have their GHG emissions data reports verified each year by an ARB-accredited verification body, beginning in 2010 for 2009 emissions. The third-party verification requirements and deadline are specified in section 95103(f) of the reporting regulation. Compliance dates are summarized at:

Only ARB-accredited verification bodies and verifiers may provide verification services to reporting entities.

On April 24, 2013, ARB presented a webinar titled "Tips for a Successful Verification" (PDF of slides) to emissions data reporters.