Set for mainnet deployment on September 30 at 18:00 UTC, Base’s Cobalt upgrade will enable B20 token issuers to configure balance seizures independently from standard transfer restrictions. For tokens where this capability is activated, holders may retain the ability to transfer funds while remaining subject to administrative reassignment.
B20 serves as Base’s native, ERC-20-compatible token standard available in both Asset and Stablecoin variants. While it already grants administrators control over roles and policies governing balance movements, it will now additionally regulate administrative authority over those balances.
While role assignments define authorized parties for specific powers, policy settings dictate which accounts are impacted by an operation. Furthermore, modifying a token’s rules and executing a balance action require separate permission verifications.
Separate seizure permissions
Introduced in the update, the seizeWithMemo administrative function transfers a designated quantity of tokens from a holder to a different address. This process maintains the total supply while bypassing standard transfer policies and holder allowances.
Before an issuer can extract tokens using this function, they must configure which accounts lose their exemption status. By default, the SEIZE_EXEMPT_POLICY setting exempts all accounts if left unassigned. However, configuring eligibility alone is not enough; execution also demands the SEIZE_ROLE, an active (unpaused) seizure function, an approved recipient, and an adequate balance.
A distinct recipient policy dictates the permitted destinations for seized tokens, and leaving this particular policy unconfigured permits any otherwise valid destination. Crucially, a holder’s capacity to execute a standard transfer does not answer either of the seizure-policy criteria.
Existing B20 transfer policies evaluate both the sender and receiver, alongside the executor when transactions happen on behalf of another account, and administrators retain the ability to modify these policies. Approving a spender does not bypass the evaluations applied to the final transfer, and these standard transfer permissions remain entirely separate from Cobalt’s seizure regulations.
Additionally, B20 currently features burnBlocked, a function allowing authorized callers to eliminate tokens held by accounts restricted by the sender transfer policy. Although Cobalt deprecates this function, it will remain functional and retain its current behavior.
Consequently, issuers have multiple options for diminishing a holder’s balance. Reassignment relocates tokens to a new address while keeping them in circulation, whereas destroying the seized supply necessitates a subsequent burn action. Both seizure and burning operations operate with distinct administrative roles and pause controls.
According to Base’s status page, the mainnet upgrade maintenance is planned from 18:00 to 20:00 UTC. The upgrade schedule indicates that the Sepolia testnet went live on September 23, with the mainnet release slated for September 30.
The v1.4.2 release incorporates Cobalt mainnet support, advising node operators to complete their upgrades by September 30 at 18:00 UTC.