Circle will begin winding down the legacy version of its Cross-Chain Transfer Protocol (CCTP V1) on Oct. 31, imposing tighter USDC transfer limits on applications that have not yet migrated before a planned contract pause on Dec. 1. Both milestones remain on schedule as of Oct. 29, 2026.
The immediate impact falls on transfer capacity. Circle’s published timeline calls for reduced burn limits starting Oct. 31, followed by a gradual performance decline. Once the V1 contracts are paused, any integrations still relying on the legacy system will be unable to move USDC between blockchains.
CCTP operates by burning USDC on a source chain and minting it on the destination chain. A burn limit caps the volume entering this process, while an attestation serves as Circle’s signed approval for the minting operation on the destination chain.
The transition has been underway for some time. Circle announced the move away from V1 on Nov. 14, 2025, and published the October-to-December timetable on Aug. 27, 2026.
Published notice and planned CCTP V1 milestonesPUBLISHED NOTICEAug. 27, 2026Schedule publishedPLANNED STARTOct. 31, 2026Burn limits start fallingGradual wind-downLimits tighten over timePLANNED PAUSEDec. 1, 2026V1 contracts pausedPlans as of Oct. 29 · schematic spacing
Explore Circle’s planned treatment
Explore Circle’s planned treatmentNew V1 transfersPending redemptions
Burn limits begin falling Oct. 31. Message limits are intended to tighten until new burns cease before the planned Dec. 1 pause.
Planned treatment of new V1 transfersCIRCLE’S PLAN · NEW V1 TRANSFERSOct. 31: limit reductions beginProgressively tighter limitsNew burns cease before full pauseDec. 1Planned pauseIntegrations left on V1 stop crosschain USDC transfers at the planned pause.
New V1 transfers progressively closeCIRCLE’S PLAN · NEW V1 TRANSFERSOct. 31Limit reductions beginLimits tightenNo new burns beforethe full pauseDec. 1V1 pause plannedPlan as of Oct. 29, 2026.
Circle says pending redemptions remain available during the wind-down, with minting allowance above pending attestations so redemptions can be processed before the full pause.
Circle’s plan for pending V1 redemptionsPENDING REDEMPTIONSPending redemptions remain availableMinting allowance maintainedAbove pending attestationsIntended processing before pauseDec. 1Planned pauseCircle says pending redemptions remain available during the wind-down.
Pending redemption completion before planned pausePENDING REDEMPTIONSRemain availableDuring the wind-downMinting allowanceKept above pendingattestationsIntended processingBefore pauseDec. 1, 2026Full pause plannedCircle’s stated plan as of Oct. 29, 2026.
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.
Circle’s migration guide outlines progressively tighter message limits until new burns cease entirely. Transfer volume is expected to reach zero before the full contract pause. This staged phase-out affects an application’s ability to continue routing transfers throughout November and at the final cutoff.
Pending redemptions receive different treatment. Circle states they will remain available during the phase-out, with minting allowances maintained above the total of pending attestations so redemptions can be processed before the full pause. The plan therefore separates the completion of outstanding transfers from the acceptance of new activity.
The distinction matters for applications managing transfers at different stages: the guide pairs a gradual halt to new burns with sufficient minting allowance to process pending redemptions. Both steps precede the full pause scheduled for Dec. 1, 2026.
CCTP V1 Applications Must Migrate to New Contracts and APIs
Migrating to V2 requires changes to contract calls and APIs. Circle notes that the newer system—now branded simply as CCTP—is incompatible with V1 integrations. Applications must update the contracts and APIs they use, along with the calls made to those contracts.
The guide identifies new addresses and interfaces, including TokenMessengerV2 and MessageTransmitterV2. In the TokenMessengerV2 interface, the depositForBurn function adds parameters for the permitted destination caller, maximum fee, and minimum finality threshold, requiring existing calls to accommodate 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 directly.
Beyond the required contract and API updates, V2 introduces Standard and Fast Transfer modes and programmable hooks for actions on the destination chain. Fast Transfer carries a variable fee based on the source chain, so migration also involves accounting for the chosen transfer mode and its associated costs.
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.