Circle plans to begin winding down the legacy version of its Cross-Chain Transfer Protocol (CCTP V1) on Oct. 31, leaving applications that still use it facing tighter USDC transfer limits before a planned Dec. 1 contract pause. As of Oct. 29, 2026, both milestones remain ahead.
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The immediate pressure is on applications' transfer capacity. Circle's published schedule calls for lower burn limits from Oct. 31, followed by a gradual decline in performance. Once the contracts are paused, integrations still pointing to CCTP V1 will stop transferring USDC between blockchains, the company says.
CCTP transfers USDC by burning it on a source blockchain and minting it on the destination blockchain. A burn limit caps how much can enter that process. An attestation is Circle's signed approval for burned USDC to be minted on the destination chain.
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The transition itself is older than the approaching deadline. Circle announced the move away from V1 on Nov. 14, 2025 and published the October-to-December timetable on Aug. 27, 2026.
Circle's migration guide describes progressively tighter message limits until no new burns can be initiated. Transfer volume is intended to reach zero before contracts are fully paused. That makes the staged phase-out relevant to an application's ability to keep routing transfers throughout November, as well as at the final cutoff.
Pending redemptions receive different treatment. Circle says they will remain available during the phase-out and that it will maintain minting allowances above the total of pending attestations, so redemptions can be processed before the full pause. The plan therefore separates completing outstanding transfers from allowing new activity.
The distinction matters for applications managing transfers at different stages: the guide pairs a gradual halt to new burns with enough minting allowance to process pending redemptions. Circle's published plan places both steps before the full pause scheduled for Dec. 1, 2026.
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Burn limits begin falling Oct. 31. Message limits are intended to tighten until new burns cease before the planned Dec. 1 pause.
New V1 activity is set to wind down while pending redemptions are processed before the planned pause.
Future scheduled changes as of October 29, 2026, not observed execution. No intermediate numerical limits, per-chain timetable, adoption data or post-pause redemption promise is shown. Diagram endpoints indicate intended process order only.
CCTP V1 apps need new contracts and APIs
V2 migration requires changes to contract calls and APIs. Circle says the newer system, now branded simply as CCTP, is incompatible with V1 integrations. Applications must update the contracts and APIs they use, alongside the calls made to those contracts.
The guide identifies new addresses and interfaces, including TokenMessengerV2 and MessageTransmitterV2. In its TokenMessengerV2 interface, the depositForBurn function adds parameters for the permitted destination caller, maximum fee and minimum finality threshold. Existing calls therefore need 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, an integration can use the V2 messages endpoint with the transaction hash to retrieve the message and attestation.
Beyond the required contract and API changes, V2 offers Standard and Fast Transfer modes and programmable hooks for actions on the destination blockchain. Fast Transfer carries a variable fee based on the source chain, according to the guide, so migration also involves accounting for the chosen transfer mode and its fees.
Some functions do not carry over. The guide lists replaceDepositForBurn as removed with no V2 equivalent. Circle also offers Arc App Kits as an optional route that abstracts routine contract-address, interface and attestation work.