A carbon registry is the record that makes a carbon credit real. A credit is not a paper certificate or an invoice: it is an entry in a registry, with a serial number, an owner and a status. This page explains what registries do, which ones matter and how to use them.
It is part of our Learn section. For the rules behind each registry, see carbon standards.
What does a carbon registry do?
A registry tracks every credit through its life. The ICVCM’s Core Carbon Principles require each crediting program to operate or use a registry to uniquely identify, record and track mitigation activities and the credits issuedSource 1.
In practice, Gold Standard describes its Impact Registry as the place where credits are issued, held, transferred and retired, and calls it the “source of truth” for information about its creditsSource 4. Registries record four things:
- Projects, with their documents and the methodology they follow
- Issuances, in batches, each credit with a unique serial number
- Holdings and transfers between accounts
- Retirements, which take credits out of circulation for good
Why serial numbers matter
A serial number lets anyone trace a credit and stops the same tonne being sold twice. Gold Standard generates a unique serial number for every issued credit, giving full traceability through its lifecycleSource 4. The Climate Action Reserve says it assigns unique serial numbers to prevent double counting, and its format encodes the project, the developer, the vintage and the issuance batchSource 6.
EX-0042-KE-2025-000118–000129
- Project
- Example cookstove project, Kenya
- Quantity
- 12 tCO₂e
- Retired for
- Jane Doe
- Vintage
- 2025
The card above is an example of the fields to look for, not a real record.
The main registries
Each major standard runs its own registry, with its own name for a credit.
Scrolls sideways to show every column.
| Registry | Program | Credit name | Focus |
|---|---|---|---|
 Verra Registry | Verified Carbon Standard (Verra) | Verified Carbon Unit (VCU) | Reductions and removals |
 Gold Standard Impact Registry | Gold Standard for the Global Goals | Verified Emission Reduction (VER) | Reductions and removals, with SDG impacts |
 ACR Registry | ACR | ACR credits | Voluntary and compliance markets |
 Climate Action Reserve registry | Climate Action Reserve | Climate Reserve Tonne (CRT) | Voluntary and compliance markets |
 Puro Registry | Puro Standard | CO₂ Removal Certificate (CORC) | Durable carbon removal only |
 Isometric Registry | Isometric Standard | Isometric credits | Carbon removal |
Logos identify the organisations named; no endorsement is implied.As of Oct 2026
Sources: VerraSource 2, Gold StandardSource 4Source 10, ACRSource 11Source 5, Climate Action ReserveSource 12Source 6, Puro.earthSource 7 and IsometricSource 8Source 13.
Governments run registries too. Under the Paris Agreement, the Article 6.4 crediting mechanism has its own registry, and countries’ national registries can connect to it to transfer authorised creditsSource 9. See Article 6 explained.
How credits move through a registry
The path is similar everywhere. Puro.earth describes it simply: credits are issued to the supplier in the Puro Registry, bought by the buyer, and retired once the buyer applies them to a climate claimSource 7.
Trading doesn’t always happen inside the registry. At ACR, credits are bought and sold directly between buyer and seller or on a linked exchange, and the parties then record the transfer or retirement on the ACR RegistrySource 5. Isometric marks retired credit batches with the status RETIREDSource 8.
How to use a registry as a buyer
You don’t need your own account to benefit from a registry. What you need is the information to find your credits.
Step 1: Ask which registry
Before you pay, ask the seller which program issued the credits and which registry holds them.
Step 2: Get the serial numbers
After retirement, ask for the serial numbers or serial range of the credits retired for you.
Step 3: Search the public view
Open the registry’s public search and look up the retirement by serial number or project.
Step 4: Check the details
Match the project, quantity, vintage and date, and look for your name as the beneficiary.
On the Verra Registry, the retirement reason and beneficial owner fields are optional and can stay private if the account holder choosesSource 3, so ask your seller to show your name.
No registry, no credit
If a seller can’t name the registry or give you serial numbers, you have no way to check that the credits exist, or that they weren’t sold to someone else too.
Where to go next
Our guide on how to verify carbon credits walks through checking a record step by step. For what retirement means and why it matters, read carbon credit retirement. Reduce what you can first, then buy credits you can find in a registry.