Sei Network is forcing a shift. Under a newly passed governance proposal known as SIP-03, exchanges and custodians that hold SEI tokens must move those assets to Ethereum Virtual Machine (EVM) compatible addresses. The deadline isn't flexible: support for SEI on the Cosmos chain ends June 15, 2026.
Why the migration is necessary
The Sei blockchain originally launched as a Cosmos-based chain. But the network has since pivoted to an EVM architecture, aligning with Ethereum's ecosystem. SIP-03 formalizes that transition. After June 15, any SEI tokens still sitting on Cosmos addresses effectively become inaccessible through standard network operations. Exchanges and custodians that don't comply risk freezing user funds or losing the ability to process deposits and withdrawals.
Who's affected and what they need to do
The proposal targets centralized exchanges, wallet providers, and any custodian holding SEI on behalf of users. Individual holders who use self-custody wallets on Cosmos will also need to move their tokens. The network has not yet published a detailed migration guide, but the expectation is that holders will use a bridge or swap mechanism to transfer SEI to an EVM address. Sei's team has said they'll release technical documentation closer to the cutoff date.
What happens if you miss the deadline
After June 15, 2026, the Cosmos chain will no longer process SEI transactions. Tokens left on Cosmos addresses won't be lost forever — the network has indicated that a recovery mechanism could be built later — but there's no guarantee. The official stance is clear: migrate before the cutoff to avoid trouble. Exchanges that fail to act could face operational headaches, including potential litigation from users who can't access their funds.
The Sei Foundation has said it will work with major exchanges to ensure a smooth migration. Still, the burden rests on each entity to update their systems. Smaller platforms with limited engineering resources may find the transition more difficult.
Next steps and unresolved questions
The clock is ticking. Exchanges and custodians have just over two years to complete the migration, but the technical work — updating wallet libraries, changing deposit addresses, testing — could take months. Sei's developers plan to release a migration tool and a list of compatible EVM wallets by the end of 2025. Until then, holders are advised to keep an eye on official channels and avoid transferring SEI to Cosmos addresses after the deadline passes.
The unanswered question: how will the network handle the inevitable stragglers? Sei hasn't detailed a post-cutoff recovery plan, leaving some users guessing whether their tokens will be retrievable at all.
