Why Relayer Repayment Chains Matter

A relayer repayment chain is the network where a bridge pays back a relayer after the relayer has delivered tokens to a user. The choice matters because a relayer may front funds on one chain and ask for repayment on another, affecting how much the bridge must move between its pools.

How does a relayer repayment chain work?

A relayer supplies tokens on the destination chain so the user can receive them before the bridge completes its settlement. Later, the bridge confirms the transfer and repays the relayer on the chain they selected. That chain is the repayment chain; it can differ from both the user’s starting chain and destination chain.

Across, for example, groups fills and repayment instructions into settlement bundles. A bundle is a batch of checked instructions for moving funds. For a plain-language view of AcrossBridge transfer methods, see the separate guide. The key point here is that the relayer’s payout location is part of the transfer’s economics.

Why can the repayment chain change fees?

Paying a relayer on the deposit chain can use funds already there, avoiding a cross-chain rebalance. If repayment is on a different chain, the bridge may need to move liquidity between its pools. Across accounts for that added liquidity cost in its fees. The relayer’s choice can therefore affect the user’s price, even though the user receives tokens on the same destination chain.

• Deposit-chain repayment: may avoid a cross-chain rebalance.
• Destination-chain repayment: can suit a relayer that needs funds where it just paid the user.
• Another supported chain: can help a relayer manage its inventory, but may require liquidity to be moved there.
• Different routes: can have different costs because liquidity conditions vary by chain and token.

Who chooses the repayment chain, and what happens next?

The relayer chooses where to receive repayment, subject to the bridge’s supported chains and transfer rules. The choice helps the relayer manage its funds across networks, but it does not change where the user asked to receive tokens. After the fill, the bridge checks that it matches the user’s deposit. Settlement instructions then direct repayment and any needed pool rebalancing.

For users, the practical takeaway is to compare the full quoted fee for the route, not just the destination chain. A route can deliver to the same place yet cost more if it needs extra liquidity movement. For relayers, repayment flexibility can reduce the need to keep equal balances everywhere, though it does not remove the cost of rebalancing.

Watch the quoted fee and the bridge’s settlement rules as routes change. Those reveal whether a repayment choice is adding a liquidity cost and where the relayer expects to receive funds.