Circle will deprecate its Cross-Chain Transfer Protocol (CCTP) V1 and complete its shutdown on December 1, 2026, requiring applications that route USDC through the legacy contracts to migrate. The phase-out begins on October 31, when V1 burn limits and transfer capacity will start declining. Circle says CCTP V2 will be the only recommended path, supporting Standard and Fast Transfer modes, programmable Hooks and future integrations with additional blockchains. The migration is not backward-compatible: integrators must adopt new contract addresses, interfaces and APIs, update TokenMessenger, MessageTransmitter and TokenMinter integrations, revise depositForBurn calls and replace legacy attestation requests with the V2 messages endpoint. Circle says users will retain access to funds during the phase-out, pending redemptions will remain available and enough minting capacity will be maintained to complete outstanding attestations. Its supported-chain matrix lists 27 blockchains, while Aptos, Noble and Sui remain identified as V1-only chains. Circle has published migration guidance and has not disclosed which production integrations still use the old contracts. CCTP processed more than $110 billion across 5.3 million transfers as of November 14, 2025, with the totals combining V1 and V2.