How carbon credits actually work — the supply, the verification, the retirement

1. Definition and standards stack

A carbon credit is a transferable unit representing one metric tonne of CO₂-equivalent either avoided, reduced, or removed from the atmosphere relative to a counterfactual baseline. The unit is only meaningful inside a programme that defines five things: baseline methodology, additionality test, leakage accounting, permanence guarantees, and uniqueness (one serial number, one registry account, one retirement event).

The governing standards stack for the voluntary market in 2026:

• ISO 14064-2:2019 — project-level GHG quantification, monitoring, and reporting requirements. Sits underneath every credible programme.
• GHG Protocol Project Accounting Standard — the inventory framework feeding Scope 1/2/3 reporting on the buyer side.
• ICVCM Core Carbon Principles (published March 2023) — ten-principle assessment framework. CCP-eligible categories so far include certain ozone-depleting substance destruction methodologies and a subset of REDD+ jurisdictional approaches under ART/TREES.
• VCMI Claims Code of Practice — governs what a buyer can claim once credits are retired (Silver/Gold/Platinum tiers tied to inventory disclosure).
• EU CRCF Regulation (EU) 2024/3012 — entered into force December 2024, framing carbon removals, carbon farming, and product carbon storage with mandatory QU.A.L.ITY criteria.

Compliance instruments (EU ETS allowances, CORSIA-eligible units, Article 6.2 ITMOs, Article 6.4 A6.4ERs) are governed separately and are not fungible with VCS or Gold Standard VCUs without explicit corresponding adjustment.

2. Mechanism in technical detail

A project moves through a deterministic pipeline. The states are observable on-registry:

Buffer pool contributions (typically 10–20% for AFOLU projects under VCS, calculated via the Non-Permanence Risk Tool) sit in a pooled account to cover reversal events. Leakage deductions are applied at quantification — for REDD+, market and activity-shifting leakage are typically discounted at 10–40% depending on belt analysis.

3. Worked example with serial

Take a Verra-registered improved cookstove project under VMR0006 (revision of VM0009 / Gold Standard TPDDTEC equivalent). A representative serial fragment looks like:

11689-447829341-447829341-VCU-040-MER-IN-1-2865-01012023-31122023-0

Decoded:

• 11689 — VCS project ID
• 447829341-447829341 — issuance block (1 unit)
• VCU-040 — Verified Carbon Unit, methodology family
• MER-IN-1 — sectoral scope, country (IN), AFOLU flag
• 2865 — internal batch reference
• 01012023-31122023 — vintage period
• 0 — crediting period instance

On retirement, Verra appends a retirement record with beneficiary, retirement reason, and date. That record is the only evidence a buyer should accept — invoices and certificates from intermediaries are not proof of retirement.

4. Irish-specific considerations

Ireland's compliance market is governed by the EU ETS for Scope 1 emitters (cement, alumina, power generation, large industrial sites) and the ESR (Effort Sharing Regulation) for non-ETS sectors — agriculture, transport, buildings. Ireland's 2030 ESR target is a 42% reduction on 2005 levels, with the Climate Action Plan 2024 setting sectoral ceilings.

Voluntary market specifics for Irish buyers:

• Domestic supply is thin. There are no large-scale Verra or Gold Standard projects on Irish soil at present. The bulk of Irish-originated units in pipeline are Woodland Carbon Code-style equivalents being developed under DAFM's forestry programme and peatland rewetting under the EU CRCF carbon farming pillar.
• EU CRCF transposition. CRCF certification methodologies are being adopted via Commission delegated acts through 2025–2026. Permanence requirements differ by activity class: ≥35 years for carbon farming, "several centuries" for permanent removals.
• CSRD / ESRS E1 reporting. Large undertakings under CSRD must disclose retired credits separately from gross/net inventory. Offsets cannot net down the gross figure under ESRS E1-7.
• Revenue treatment. Voluntary credit purchases are generally treated as operating expense; VAT treatment follows the location-of-supply rules for emission allowances under the reverse charge mechanism for compliance units.

5. The IMPT position

IMPT operates as an aggregator-retiree, not a developer. The mechanism:

1. A hotel booking executes through the IMPT booking layer.
2. Commission accrues to IMPT from the supplier on confirmed stay.
3. From that commission pool, IMPT procures and retires one tonne CO₂e per booking from a Verra VCS or Gold Standard project.
4. The retirement is mirrored on-chain — the on-chain token references the registry serial, vintage, project ID, and retirement timestamp.
5. The buyer (the traveller, or the corporate travel programme) gets a serial-number lookup that resolves back to the underlying Verra or Gold Standard retirement record.

Projects in current rotation are filtered for ICVCM CCP eligibility where available, with a preference for removals and high-integrity avoidance (ODS destruction, certain landfill gas, ARR projects with credible buffer pools).

6. Common mistakes Irish buyers make

• Buying vintage without thinking. A 2014 vintage REDD+ credit is not equivalent to a 2024 vintage ARR removal. Vintage drift erodes claim credibility, particularly under VCMI Gold/Platinum tier rules.
• Confusing certificates with retirements. A PDF "carbon neutral certificate" with no registry serial is unverifiable. Always demand the serial and resolve it directly on the issuing registry's public lookup.
• Double-claiming. Where credits originate in a host country with a Paris NDC, absence of a corresponding adjustment means the host country also counts the reduction. This is acceptable for voluntary use but precludes most CORSIA Phase 1 use cases.
• Treating offsets as Scope 1/2 reductions. Under GHG Protocol, retired credits are reported as a separate line. Inventory reductions require physical or contractual instruments inside the inventory boundary (e.g. Guarantees of Origin for Scope 2 market-based).
• Ignoring permanence risk. Nature-based avoidance credits without buffer pool participation, or with thin reversal monitoring, are the recurrent failure mode. Check the Non-Permanence Risk Tool score on the PD.

7. Verification and audit pattern

For a buyer-side audit (internal or external assurance under ISAE 3410), the minimum evidence chain is:

1. Procurement record — purchase contract, beneficiary nomination instruction.

Procurement-grade carbon assessment

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