Child-Pays-for-Parent (CPFP)
A fee-bumping technique where a new, high-fee transaction spending an unconfirmed output incentivizes miners to confirm both it and the original low-fee transaction together.
Child-Pays-for-Parent is a technique for speeding up a stuck, unconfirmed Bitcoin transaction (the "parent") by creating a new transaction (the "child") that spends an output from that parent, attaching a high enough fee to the child that it makes the combined package profitable for a miner to include — since confirming the child requires also confirming its parent. Unlike Replace-by-Fee (see Kaavon's "Replace-by-Fee (RBF)" glossary definition), CPFP doesn't replace the original transaction at all; it adds a second transaction specifically to make including both together worthwhile.
CPFP is particularly useful for the transaction's recipient, rather than just its original sender, since the recipient of an unconfirmed payment can create the high-fee child transaction themselves to speed up their own incoming payment, without needing the original sender's cooperation at all. This makes CPFP a valuable fee-bumping option in situations where the party wanting faster confirmation isn't the one who originally set — and potentially underpaid — the stuck transaction's fee.
Examples
- A merchant who received an unconfirmed payment with too low a fee can use Child-Pays-for-Parent to attach a high-fee child transaction, incentivizing miners to confirm both transactions together.
- Unlike Replace-by-Fee, which only the original sender can use, Child-Pays-for-Parent can be initiated by the recipient of a stuck transaction, since it only requires spending an output the recipient already controls.