Carbon Credit Glossary

Key terms used in the voluntary carbon market — defined for CFOs, controllers, and auditors.

Carbon Credit
A tradable certificate representing one metric tonne of CO₂ equivalent (CO₂e) reduced, avoided, or removed from the atmosphere. Issued by registries after independent verification.
Vintage
The calendar year in which the emissions reduction or removal actually occurred. Auditors use vintage to match credits to the reporting period being claimed.
Retirement
The permanent cancellation of a carbon credit in the registry so it cannot be resold or reused. Retirement is the act that enables an organization to make a climate claim.
Serial Number
The unique identifier assigned to a specific block of credits by the issuing registry. Serial numbers enable complete chain-of-custody traceability from issuance through transfer and retirement.
Climate Claim Statement
The formal assertion made when retiring credits — e.g., 'Acme Corp retired 500 VCUs (Verra, 2022 vintage) to offset 500 tCO₂e for FY2023.' Must be timestamped and linked to specific retired credits to be audit-defensible.
Additionality
The principle that an emissions reduction would not have occurred without the carbon credit financing. A project must demonstrate additionality to receive registry approval.
Permanence
How long the carbon sequestration or reduction will last. Forest projects carry permanence risk. Registries manage this through buffer pools — a percentage of credits held in reserve to cover potential reversals.
Co-benefits
Positive social, environmental, or economic impacts beyond the primary carbon reduction — biodiversity protection, local employment, clean water access.
VCU (Verified Carbon Unit)
The credit unit issued by Verra under the Verified Carbon Standard (VCS). One VCU = one tonne of CO₂e reduced or removed.
GS VER (Gold Standard Verified Emission Reduction)
The credit unit issued by Gold Standard. GS VERs require projects to demonstrate sustainable development co-benefits in addition to emissions reductions.
ACR (American Carbon Registry)
A US-based voluntary carbon registry operated by Winrock International. ACR credits are recognized by the California Air Resources Board for use in the California Cap-and-Trade program.
Subledger
A detailed subsidiary ledger that supports a general ledger account. A carbon credit subledger tracks individual credit lots, retirements, and valuations, feeding into the intangible assets or inventory line on the balance sheet.
Impairment
A reduction in the carrying amount of a carbon credit below its book value. Under IAS 36 and ASC 350, credits must be tested for impairment when indicators suggest the carrying amount may not be recoverable.
Cost Basis
The original purchase price of a carbon credit, including directly attributable transaction costs. Used to calculate gain or loss on retirement and to test for impairment.

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