California Air Resources Board

This website is for CARB-accredited GHG verifiers for CARB's Mandatory Reporting Regulation. Please contact us at ghgverify@arb.ca.gov with questions. 

Recent Updates

Cal e-GRRT Step by Step Guide for Verifiers

2018 MRR Regulation (PDF) (MS Word)
List of Reporting Entity Contacts and COI Status for accredited verifiers (password required, next update Nov 2026)
CARB Verification Services Audit Checklist
Application for Upgrade to Lead Verifier or to add Sector

Webinar for Accredited Verifiers

The Verifier Kickoff Webinar for 2025 data occurred in February 2026. Accredited verifiers can view the slides and recordings of this and of previous webinars at the link below.

Link to webinar slides for accredited verifiers (password required)

Verifier Accreditation Training

CARB completed an MRR verification accreditation training in November 2020 and in February 2024. The next accreditation training will be held in February 2027. For more information about verifier accreditation training, please view our Frequently Asked Questions document.

Links to updated training videos and presentations will be posted in January 2027.

Archive of past training

Course 1 (Verifier Training)
Course 1 recordings
1.1 slides (b/w), 1.2 slides (b/w), 1.3 slides (b/w), 1.4 slides (b/w), Handouts | case study | case study answers

Course 2 (Transactions)    
Course 2 recordings 2.1 (Electric Power Entities) slides (b/w) | 2.1.CS w/o answers | Handouts), 2.2 (Transportation Fuel Suppliers) slides (b/w), 2.3 (Natural Gas Suppliers) slides (b/w), 2.4 (Carbon Dioxide Suppliers) slides (b/w), Course 2.2-2.4 Handouts

Course 3 (Oil and Gas)
Course 3 recordings, 3.1 (PNG Systems) slides (b/w), 3.2 (Refineries) slides (b/w), 3.3 (Hydrogen Production) slides (b/w), Case Studies

Course 4 (Process emissions training from 2015)

Errata (as of 2/23/24)

Guidance

Reporting guidance is posted on the guidance page.
Technical Guidance for Assuring Measurement Device Data Accuracy
Example Calculation for Verification of Reprocessed Tomato Product Data

Listserve Information
There are 2 CARB listserves related to GHG Mandatory Reporting:

1. Public reporting & verification list (ghg-rep).  You may subscribe/unsubscribe yourself, including changing your email address.
2. MRR accredited verifier-only list (ghgverifiers).  Please send ghgverify@arb.ca.gov an email if your email address changes.  Verifiers cannot update this list without CARB assistance.