Replace-by-Fee (RBF)

Definition

Replace-by-fee is a transaction replacement mechanism that can let an unconfirmed Bitcoin transaction be superseded by a conflicting transaction offering sufficient additional fees under applicable node policies. Wallets use it to increase the incentive for miners to confirm a payment when the original fee is inadequate. BIP-125 describes an opt-in signaling approach, but replacement policies can differ across implementations and software versions, so signaling should not be treated as the only possible condition everywhere. A replacement is a new transaction and can have a different transaction identifier. It must still satisfy ordinary spending authorization and validity requirements. RBF does not edit an already confirmed transaction or guarantee that the replacement will arrive first or be mined. Recipients should therefore distinguish pending transaction observations from confirmed settlement, while senders should review whether their wallet preserves the intended payment outputs during a fee adjustment.