Multisignature Bridge Withdrawals Need Two Approvals

A treasury can withdraw assets from Polygon PoS through its multisig by approving a burn on Polygon, then a claim on Ethereum. Polygon’s support guide says the withdrawal burns the Polygon tokens and unlocks the matching assets on Ethereum after the bridge processes the claim. The two steps need separate transactions, so a team should plan for two rounds of approvals.

How does a multisig bridge withdrawal work?

A multisig requires a set number of signers to approve a transaction before it executes. Safe’s documentation describes this threshold model: for example, a wallet configured with a 2-of-3 threshold needs two of its three signers to approve. When the treasury initiates a withdrawal, the approved Polygon transaction burns the bridged tokens.

Polygon’s PoS bridge then waits for the Polygon block containing that burn to be included in a checkpoint on Ethereum. Polygon’s proof-generation project says the final exit uses a cryptographic proof of the burn; the treasury submits a separate claim transaction on Ethereum to release the original assets. For a fuller explanation of the bridge stages, see Polygon Bridge.

What must treasury signers approve?

Signers approve the burn transaction first, then approve the Ethereum claim once the checkpoint and proof are available. The Polygon Support instructions say the withdrawal requires gas on both networks: POL for the Polygon transaction and ETH for the Ethereum claim. A treasury should keep enough of each available to complete both stages.

Before signing, the team should agree on the transaction details and check them independently:

• The asset, amount and Polygon source account.
• The destination address that will receive the released assets on Ethereum.
• The transaction call and proof details for the Ethereum claim.
• The gas balance on each network and the total amount expected to arrive.

Threshold approval reduces the chance that one compromised signer can move funds alone, but it does not verify that a proposed transaction is correct. Each signer should review the address, amount, network and transaction call before approving.

How should a treasury plan the withdrawal?

Start by confirming that the treasury can submit transactions on both networks. If its multisig is available on Polygon and Ethereum, the team can use the same approval process for the burn and claim; otherwise, it needs a valid way to make the Ethereum claim to the intended treasury address. Polygon’s support guide says a withdrawal cannot be cancelled once initiated, so the team should settle the destination and amount before approving the first step.

Next, assign who proposes the burn, who checks its details, and who will monitor the checkpoint and prepare the claim. The checkpoint adds a wait between transactions, and the eventual Ethereum claim also requires a fresh approval threshold. Teams should account for that delay and Ethereum gas before moving funds they expect to use immediately.

For most treasury teams, a threshold that requires more than one independent signer for both transactions is a practical balance: it distributes control while allowing the withdrawal to proceed if one signer is unavailable. The key operational point is that approving the Polygon burn does not finish the withdrawal; the assets reach Ethereum only after the team completes the claim.