Moving Carbon Credits Between ICR and Carbonmark: A Technical Guide

A practical guide for project developers, traders, and buyers holding ICR credits.

Carbon credits issued on the International Carbon Registry (ICR) can be transferred into a Carbonmark account, listed for sale on our marketplace, managed and retired from your dashboard, and sent back to ICR. This guide covers ICR's registry and carbon standard, two ICR projects available on Carbonmark today, how credit transfers and retirements function, and where listed credits are available.

Key Takeaways

• ICR credits can be transferred into a Carbonmark account and listed for sale, and moved back to ICR when needed.
• You only need to connect your accounts once, then approve each transfer in ICR. You request an import from your Carbonmark Portfolio and accept it from your ICR inventory. Carbonmark cannot move credits out of an ICR account on its own.
• Retirements are mirrored 1:1, fractions included. A retirement through Carbonmark is recorded onchain with a public certificate, and a matching retirement is recorded on ICR's registry, down to 0.001 tCO₂e (1 kg).
• Buyers can take credits home to ICR. Credits export to the ICR organization connected to the Carbonmark account, so a buyer with an ICR account can move purchased credits there. Credits must be delisted from the marketplace before they can be transferred back to ICR.
• Two ICR projects live on Carbonmark today are highlighted in this guide: a regenerative agriculture program in Italy (ICR-48) and a reforestation project in Paraguay (ICR-349).

What ICR is

The International Carbon Registry (ICR) is a greenhouse gas (GHG) program and electronic registry for climate projects, founded in 2020 and headquartered in Iceland. It issues ICR Carbon Credits (ICCs) to projects that conform to its own requirements and to ISO 14064-2, the international standard for quantifying and reporting project-level emission reductions and removals.

That makes ICR both the program and the registry. It sets the rules a project must meet, and it runs the system that records issuance, tracks every transfer, and records retirements so a credit cannot be claimed twice. (Compare EcoRegistry, which is the registry for a separate standard, Cercarbono.)

ICR is endorsed by the International Carbon Reduction and Offset Alliance (ICROA), and it is applying for approval under the Integrity Council for the Voluntary Carbon Market (ICVCM) and CORSIA, the aviation sector's offsetting scheme.

The types of projects ICR supports

ICR is open by design. Any project type can be registered, provided it meets ICR's requirements, and its approved methodology list spans 17 sectoral scopes, from energy and waste handling to agriculture, afforestation and reforestation, and carbon removals.

Two ICR projects on Carbonmark today show that range.

Reducing GHG Emissions and Increasing Carbon Sequestration in Italian Agriculture (ICR-48) pays farmers to change how they farm. Developed by Alberami SRL (now Radica) with the support of the Agroimpulso Foundation, it works with more than 300 farmers in Puglia and surrounding regions on practices such as minimal or zero tillage, year-round green cover, intercropping, hedgerows, and a ban on burning residues. Participating farms cut synthetic fertilizer use by at least 15%.

The program runs on a 20-year timeline, with an initial focus on 10,000 hectares and a target scope of more than 350,000. Remote sensing is used to monitor the practices.

The project page shows 15,540.94 tonnes retired through Carbonmark and 155 tonnes listed as of November 2026, with more inventory expected.

Forestal Río Aquidabán (ICR-349) restores 301 hectares of degraded grassland in Concepción, in northeastern Paraguay. It is a silvopastoral system: trees and cattle share the same land. The project launched in 1999 under a benefit-sharing agreement between developer Global Woods and a Paraguayan ranching family.

It reports more than 200,000 tonnes of CO₂ sequestered by 2025, with verified removals of roughly 8,000 tCO₂ a year. Validation and verification are carried out by TÜV Rheinland Energy & Environment GmbH. Since 2024, camera traps and acoustic monitors have recorded cougars, anteaters, and armadillos on the site.

Supply is deeper here: 70,515.34 tonnes remain across vintages from 2000 to 2020, as of November 2026.

The technology ICR uses

ICR's differentiator among registries is that its credits start life on a public blockchain. Three points illustrate that.

• Credits issued natively as tokens. ICR issues ICCs as tokens on a public blockchain, so issuance, transfer, retirement, and cancellation sit on a public transactional record. There is no separate bridging step that wraps a registry entry into a token after the fact. This is what makes a clean handshake with an onchain marketplace like Carbonmark possible.
• An app model for third-party access. ICR's API lets an organization install an app and grant it scoped permissions. The Carbonmark connection is one of those apps. Installing it lets Carbonmark see your inventory and request transfers. It does not let Carbonmark move credits unilaterally.
• Registry-layer tokenization with financial institutions. In July 2025, ICR and EcoRegistry completed testing on Kinexys by J.P. Morgan's blockchain application for tokenizing credits at the registry level, alongside S&P Global Commodity Insights.

ICR is also candid about what a blockchain does not do. Its own documentation notes that blockchain "does not determine whether a carbon credit is environmentally high quality." Quality still comes from the methodology, the validation, and the verification. The ledger makes the record auditable.

How to transfer credits from ICR to Carbonmark

This is the path for a project developer or trader who holds credits on ICR and wants to list them for sale, or retire them, through Carbonmark.

The transfer starts in Carbonmark and finishes in ICR. You request the credits from your Carbonmark Portfolio, then approve the request from your ICR inventory.

Before you start

• An active Carbonmark account with access to your Carbon Portfolio.
• An ICR organization account holding the credits you want to move. The ICR user needs admin privileges in that organization to install the Carbonmark app and accept transfers.

Connect your ICR organization (one time)

1. Log in to Carbonmark and open your Portfolio.
2. Click Import Carbon Credits, select International Carbon Registry, and click Next.
3. Click Connect to ICR and log in to ICR if prompted.
4. Review the Carbonmark app permissions and click Install on your ICR organization. When the success message appears, close the window and return to your Portfolio.

Each transfer

1. From your Portfolio, click Import Carbon Credits, select International Carbon Registry, and click Next. The Import credits screen lists the credits your ICR organization holds.
2. Select the asset, enter a Quantity, and click Transfer Credits.
3. Follow the link in the confirmation popup to your ICR organization's Inventory page, where the request is waiting.
4. Click Accept, then confirm. The credits are sent to the Carbonmark account address shown on the ICR screen.

Transfers usually take a few seconds, and occasionally a few minutes. Refresh your Portfolio if the credits have not appeared. An open request does not expire on the Carbonmark side: you can accept it from your ICR inventory at a later date.

Check the wallet address before you accept. Confirm the address shown in ICR matches your Carbonmark account, and when in doubt, request a small amount first. The smallest transfer is 0.001 credits.

Then list or retire. Once credits appear in your Portfolio, set your price and list them on the Marketplace, or retire them in your own name. Carbonmark charges sellers nothing to onboard or list; fees apply on the buyer side when a transaction happens. Marketplace listings are also immediately available to our API client network, which includes e-commerce, fintech, and carbon software platforms.

The full procedure, with screenshots, is in the ICR import guide in our developer docs, alongside an overview of how Carbonmark integrates registries. For the launch of two-way transfers, see our announcement of seamless import and export of ICR credits.

How to transfer credits from Carbonmark to ICR

Credits export to the ICR organization connected to the Carbonmark account. That applies to buyers as well as sellers: if you purchase ICR credits from a merchant on Carbonmark and you have an ICR account, you can connect it and transfer the credits there.

Before you start

• You have ICR-issued credits in your Carbonmark Portfolio.
• Your ICR organization is connected to your Carbonmark account (the same one-time Connect to ICR step, started from Export Carbon Credits).
• Your credits are delisted. Only credits that have been delisted from Carbonmark's marketplace can be transferred back to ICR. You can delist them from your Carbonmark dashboard.

Each transfer

1. From your Portfolio, click Export Carbon Credits, select International Carbon Registry, and click Next. The Export credits screen lists the ICR credits held in your Carbonmark wallet.
2. Select the asset and enter a Quantity.
3. Click Transfer Credits, then enter your Carbonmark account PIN to finalize.
4. Follow the link in the confirmation message to your ICR organization's credit inventory, and check that the expected project and amount appear.

Exports are irreversible. Confirm that you are connected to the correct ICR account before you transfer. The smallest transfer is 0.001 credits.

The steps are documented with screenshots in the ICR export guide, and both directions for every connected registry are in the transfer credits guide.

How retirements are recorded

When an ICR credit is retired through Carbonmark, the retirement is recorded on Polygon with a public Carbonmark certificate, and a matching retirement is recorded on ICR's registry on a 1:1 basis. The registry record and the onchain certificate describe the same tonne and share the transaction information.

• Public proof of every retirement. Each retirement produces an onchain transaction hash and a certificate at app.carbonmark.com/retirements/{address}/{number} that anyone can open. The Carbonmark retirement page also links to the matching record on ICR's registry. Buyers use this in sustainability reports; sellers use it as evidence that their credits were retired, not resold.
• Fractional retirement, mirrored. ICR credits retire on Carbonmark from 0.001 tCO₂e (1 kg), and fractional retirements are mirrored on ICR's registry the same way whole tonnes are. This is what makes per-transaction, per-product, and per-inference offsetting possible.

The two projects above show it in practice. Their retirement totals read 15,540.94 and 1,699.862 tonnes. Those decimals are not rounding. They are fractional retirements.

Where listed credits are available

A single listing is visible to every Carbonmark channel at the same time: the Marketplace, the API, hosted checkout links, and the agent endpoints. Sellers do not maintain separate inventory per channel.

• Marketplace (app.carbonmark.com). Self-serve buying and retiring for businesses and individuals, with card payment via Stripe. Buyers filter by project type, country, registry, vintage, co-benefits, and price.
• Carbonmark API. Programmatic discovery, quoting, and retirement for software companies, fintechs, logistics platforms, and ESG reporting tools. Version 20 is the current stable release. Integrators retire on demand with no pre-purchased inventory, which means a seller's listing can be consumed one kilogram at a time by dozens of applications. The developer docs cover the full flow.
• API Checkout Service. Hosted, Stripe-powered checkout links so an e-commerce store or app can sell and retire credits without building payment infrastructure. See API and Integrations for an overview of both.
• Agent endpoints (x402 and MCP). Carbonmark's x402 endpoint lets AI agents discover credits, quote live prices, pay in USDC, and retire in a single HTTP flow. A Model Context Protocol (MCP) integration exposes the same actions to agent frameworks.

Why list on Carbonmark

• Zero-cost onboarding, no exclusivity. There are no seller-side listing fees and no requirement to delist elsewhere. Sellers set their own price and can change it at any time.
• Instant settlement. Payment arrives when the credit sells. Sellers can settle in stablecoins onchain or offramp to a bank account through Carbonmark's bank-payout partner.
• A track record. Carbonmark has retired more than 1,200,000 tCO₂e on behalf of clients across 150+ listed projects on six continents.

How Carbonmark records and connects

• A public blockchain as the system of record. Every listing, trade, and retirement is a transaction on a public blockchain. For ICR credits, that chain is Polygon. There is no internal ledger to reconcile against the chain afterward, and no hidden intermediary between seller and buyer.
• Registry connectivity in both directions. Carbonmark is connected to ICR, Puro.earth, and EcoRegistry for credit transfers. Where a registry supports it, retirements are mirrored back to the host registry on a 1:1 basis, so the registry and the chain agree.
• One data shape across registries. Carbonmark is aligning its project and credit data with Version 2.0 of the Carbon Data Open Protocol (CDOP), an open-source schema for describing carbon credits (the current mapping is on our data attributes page). The goal is that a project record from ICR, Puro.earth, or EcoRegistry comes out of the API in one consistent shape.

If you hold credits on more than one registry, the two transfer integrations we have written up work differently:

Getting started

If you hold ICR credits, the fastest way to see how the connection works is to open your Carbonmark Portfolio, connect your ICR organization, and import a small test quantity. Developers can explore the connected inventory through the Carbonmark API with a free sandbox key. If you are managing a portfolio at volume or want help structuring a listing strategy, talk to our Solutions Team.