Circle plans to begin winding down the legacy version of its Cross-Chain Transfer Protocol (CCTP V1) on October 31, reducing USDC transfer limits before pausing the contracts entirely on December 1. Applications still relying on V1 integrations will face progressively tighter capacity constraints during this transition period.
CCTP transfers USDC by burning it on a source blockchain and minting it on a destination blockchain. The wind-down involves gradually reducing burn limits—the cap on how much USDC can enter this process—until new burns cease before the full contract pause.
Circle announced the move away from V1 on November 14, 2025, and published the October-to-December timetable on August 27, 2026. The staged phase-out is designed to allow applications to route transfers throughout November while completing outstanding activity before the final cutoff.
Pending Redemptions to Remain Available
During the wind-down, Circle says pending redemptions will remain available and will maintain minting allowances sufficient to process all pending attestations before the full pause. This approach separates completing outstanding transfers from blocking new activity, allowing applications to manage transfers at different stages of completion.
Migration to V2 Requires Technical Updates
CCTP V2, now branded simply as CCTP, is incompatible with V1 integrations. Applications must update their contract calls and APIs to migrate to the new system.
Key changes include new contract interfaces such as TokenMessengerV2 and MessageTransmitterV2. The depositForBurn function adds parameters for permitted destination caller, maximum fee, and minimum finality threshold, requiring existing calls to account for the new interface.
The attestation workflow also changes. Instead of extracting message bytes from an onchain transaction and hashing them before requesting an attestation, integrations can use the V2 messages endpoint with the transaction hash to retrieve the message and attestation directly.
New Features and Removed Functions
V2 offers Standard and Fast Transfer modes, with Fast Transfer carrying a variable fee based on the source chain. Programmable hooks allow actions on the destination blockchain. Some functions do not carry over to V2, including replaceDepositForBurn, which has no equivalent in the new version.
Circle also offers Arc App Kits as an optional route that abstracts routine contract-address, interface, and attestation work.
