Withdrawal fees on Polyester exist solely to cover external blockchain gas costs.
All protocol transactions on Polyester Chain (including burning uAssets, moving assets between contracts, transferring from the Funding Account to Zipper, and any Zipper-side Polyester Chain actions) are gas-sponsored by Polyester through gas abstraction. Users only pay for execution on the destination blockchain.
How Withdrawal Fees Work
When a user submits a withdrawal, Zipper estimates the external network gas cost required to complete delivery on the destination chain based on current network conditions. A small safety premium is added to handle short-term gas volatility.
Withdrawal fees cover only the destination network gas cost.
How Fees Are Paid
Withdrawal fees are paid using the Polyester version of the destination chain’s native gas token.
For example:
- Withdrawing USDT to Ethereum requires ETH in the Funding Account.
- Withdrawing USDT to Base also requires ETH (Base's native gas token).
- Withdrawing BTC to Bitcoin requires BTC.
If a user does not have enough of the required gas token in their Funding Account, Polyester will prompt them to deduct a portion of the withdrawal and auto-convert it into the required gas token to cover the external network fee.
The destination address only receives the withdrawn asset and never needs to hold native gas tokens itself.
Where Withdrawal Fees Go
All withdrawal fees are routed to the Zipper Withdrawal Vault.
Funds in this vault are used exclusively to pay external-chain gas costs when executing withdrawals. The vault is on-chain and publicly auditable.
Zipper Withdrawal Vault (EVM): 0x8F3A7B1D92C4E6A0F1D9B7C3A5E2F4B9D1A6C8E2