What SIP-03 means for exchanges and custodians
There four upgrade paths for exchanges and SEI token custodians. This integration must be completed by June 15, 2026, prior to Cosmos deprecation
The Sei protocol is completing its transition to a unified, EVM-only architecture. For exchanges, custodians, and other service providers that currently support SEI token deposits and withdrawals using native (sei1...) addresses, this means migrating customer holdings to EVM (0x...) addresses before support for Cosmos is deprecated.
This post explains what's changing and where to get support. For the full technical reference, see the Exchange and Custodian Upgrade technical reference in the docs.
What exchanges and custodians need to know
Sei EVM is not a separate chain. It's the same chain with a second way to interact with it. This is the single most important framing for integration teams.
Many exchanges currently treat "Sei" (native) and "Sei EVM" as two separate chains in their internal systems. Any integration treating them as two distinct chains needs to be consolidated into a single integration before support for Cosmos and IBC-related functionality is deprecated.
Every native sei1... address has exactly one corresponding 0x... address, determined by the public key the addresses are derived from. They are not freely pairable, and association does not create the pairing, it only registers it on-chain. Because the pairing already exists at the keypair level, no funds need to move for an exchange that surfaces the corresponding EVM address to its customers.
The four options for upgrading customer holdings to EVM are detailed in the technical reference Exchange and Custodian Upgrade technical reference.
What happens after deprecation
After deprecation of Cosmos, CosmWasm, and IBC related functionality:
- Exchanges and their users will not be able to access or transfer funds held under unassociated native addresses.
- Cosmos-native transaction interfaces will no longer be available. Exchanges will not be able to broadcast Cosmos-format transactions, sign with Cosmos key derivations against the live chain, or interact with the chain through Cosmos RPC endpoints.
- Address associations can no longer be created through a Cosmos wallet.
Exchanges and custodians need to complete this upgrade prior to June 15, 2026.
Support
For technical questions about exchange migration, contact the Sei Labs team via the Sei Tech Chat on Telegram, or join the Discord.
