Retirement Receipt

Each receipt is an on-chain record that permanently and immutably links to the retirement transaction. This prevents double counting and double claiming by providing a single, verifiable source of truth. The receipt includes metadata such as the project ID, vintage year, and retirement timestamp, which are permanently recorded on the blockchain.

Retirement Receipts follow a common data structure, such as the C3T or TCR standards, to ensure interoperability across platforms. This schema typically includes:

• Project Details: Registry, methodology, location.
• Credit Details: Vintage, quantity, serial numbers.
• Retirement Details: Beneficiary, date, retiring entity. Standardization allows wallets, marketplaces, and carbon accounting software to parse and display the data uniformly.

As an NFT, the receipt can be integrated into smart contracts and decentralized applications (dApps). This enables automated, trustless workflows, such as:

• Triggering a reward or proof-of-green NFT upon retirement.
• Serving as verifiable input for on-chain carbon accounting.
• Being used as collateral in DeFi protocols that recognize its value. This composability is a key advantage over traditional, siloed retirement records.

Anyone can independently verify the retirement by examining the public blockchain. The receipt's transaction hash points directly to the retirement event on a carbon registry bridge (e.g., Toucan, C3). This creates an audit trail that is transparent, permissionless, and far more accessible than traditional corporate or registry-level reports.

The receipt cryptographically attributes the environmental benefit to a specific entity, typically the retiring wallet address. This provides unambiguous proof of ownership of the climate action, which is crucial for corporate sustainability reporting (ESG), product claims, and regulatory compliance. The receipt is the definitive asset proving that entity 'X' retired credit 'Y'.

By turning a one-time retirement event into a persistent, tradable data object, Retirement Receipts enable novel financial and reputational markets. Potential applications include:

• Marketplaces for retired credits (representing the claim, not the credit itself).
• Reputation systems based on verifiable retirement history.
• Fractionalization of large retirement events for broader participation. This transforms retirement from an endpoint into a starting point for new value streams.

The retirement receipt's core function is realized during the redemption process. This involves:

• Burning the receipt: The holder sends the token (e.g., an LRT) back to the issuer's smart contract.
• Claiming the underlying assets: The contract returns the principal staked asset (e.g., stETH) plus any accrued rewards.
• Settlement delay: There is often a cooldown or unbonding period (e.g., 7 days for EigenLayer withdrawals) between initiating redemption and receiving funds, reflecting the underlying protocol's security constraints.

By tokenizing a locked position, retirement receipts become powerful DeFi Lego bricks. Common integrations include:

• Collateral in Lending Protocols: Protocols like Aave or Morpho may accept high-quality LRTs as collateral for loans.
• Liquidity Pools: Receipts are paired with stablecoins or ETH in Automated Market Makers (AMMs) like Uniswap to create liquid secondary markets.
• Yield Aggregation: Vault strategies in protocols like Yearn can automatically manage and compound yields from a basket of different retirement receipts.

Retirement receipts abstract complex operational tasks from the end user, effectively delegating both risk and reward management to the issuer. This involves:

• Operator Risk: The issuer selects and monitors the node operators or AVS operators, concentrating slashing risk.
• Reward Optimization: The issuer's strategy determines which services to restake with to maximize yield.
• Protocol Risk: The holder assumes smart contract risk of the receipt issuer in addition to the risks of the underlying restaking and staking protocols.

A carbon credit is a tradable certificate or permit representing the right to emit one metric ton of carbon dioxide or an equivalent amount of another greenhouse gas. It is the underlying environmental asset that is permanently retired to generate a Retirement Receipt.

• Key Types: Voluntary Emission Reductions (VERs) and Certified Emission Reductions (CERs).
• Purpose: Used by companies and individuals to offset their carbon footprint.
• Retirement: The final, irreversible act of taking a credit out of circulation to claim its environmental benefit.

A carbon registry is a centralized database that issues, tracks, and retires carbon credits, ensuring each credit is unique and not double-counted. It is the authoritative source that a Retirement Receipt cryptographically links to for verification.

• Examples: Verra (VCS), Gold Standard, American Carbon Registry.
• Function: Maintains serial numbers, project details, and retirement status for all credits.
• On-Chain Linkage: Retirement Receipts use registry attestations or oracle data to prove a specific credit's retirement status on the registry's ledger.

Proof of Retirement is the verifiable evidence that a carbon credit has been permanently retired. A Retirement Receipt is the standardized, on-chain manifestation of this proof.

• Components: Typically includes the credit's serial number, retirement date, retiring entity, and a link to the registry record.
• Immutability: Once minted on a blockchain, the proof becomes tamper-proof and publicly auditable.
• Contrast with Offset: An 'offset' is the claim of environmental benefit; the Proof of Retirement is the auditable support for that claim.

An on-chain attestation is a cryptographically signed statement of truth recorded on a blockchain. In this context, it is the technical method used to verify the legitimacy of a Retirement Receipt.

• How it Works: A trusted entity (e.g., a registry oracle or a protocol) signs a message containing the retirement details. This signature is stored on-chain and can be verified by anyone.
• Standards: Projects like EAS (Ethereum Attestation Service) provide a schema for creating standardized, portable attestations for retirements.
• Purpose: Replaces the need to trust a single intermediary, enabling decentralized verification of environmental claims.