Priority Fee Refund

Get refund for the ETH Mainnet MEV Bundles

Summary

The priority fee refund program allows transaction source partners (searchers, traders, wallets, Telegram bots) to receive back a portion of the priority fee without sacrificing inclusion rate. Builders participating in the program bid on the percentage from the profit the builders have made from the bundle priority fee they are willing to refund.

To maximize the refund - searchers should submit the bundles ONLY to bloXroute and not directly to other builders. If a bundle is received by other builders, there will be no refund available.

It is very simple to send a "blxr_submit_bundle" request with refund, just make sure to use the following two parameters in your request payload:

• priority_fee_refund: true

• refund_recipient: <wallet-address>

Approach

User submits bundles, with priority fee refund flag, to bloXroute infrastructure (most users submit bundle to Cloud API, while users with Enterprise Elite plan or above can submit it to gateway). bloXroute holds the bundles for a few seconds before the next scheduled slot to determine which builder, that participates in the program, has the highest chance to win the block. bloXroute will only forward the bundle to this builder. bloXroute continues to monitor the chances of the builder to win the block and if the chances are low - the bundle would be sent to all builders requested by the user. If several builders have similar chances to win the slot, bloXroute will send the bundle to the builder which bids the highest in the priority fee refund auction.

Example

For instance, block builder A is a participating builder in this program, and block builder B is a builder not in the program. bloXroute keeps checking the values of blocks built by various builders at different times for the current slot.

• Case 1 [builder A keeps this bundle as an exclusive bundle]: If builder A’s block is always more profitable than builder B and other builders’ for all timestamps that bloXroute performs checks at, then the bundle would be sent to builder A exclusively.

• Case 2 [builder A and other builders all receive the bundle]: If builder B’s block becomes more profitable than builder A’s at any time in the block bidding process, then the bundle would be forwarded to all the block builders (including builder A, builder B and others) requested by the user.

Receiving Refund

Bundles that remain exclusive will be eligible for refund. The builders share a portion of the gas fees (priority fees) in the form of refund with the searcher who submits the bundle. The refund amount is based on the builder block profit. The higher the profit the builder is able to keep, the higher the refund amount will be. Therefore, the refund amount (or percentage) is dynamic for each specific opportunity, and the refund payment happens on chain up to 1 - 2 hours after the bundle lands.