CPFP

CPFP, short for Child Pays for Parent, is a Bitcoin fee-bumping technique. A user spends an output from an unconfirmed low-fee transaction in a new child transaction with a higher feerate. Miners that evaluate the pair together can profit by confirming both transactions, so the expensive child helps pull the parent into a block.

Wallets use CPFP when the original fee is too low for current mempool conditions and the spender of an output from that transaction can create the child. That can help either the sender or the receiver accelerate confirmation, depending on who controls a spendable output.

CPFP depends on relay and mining policy rather than consensus alone. Nodes and miners need to accept the low-fee parent and consider the package's combined economics. Proposed improvements such as package relay aim to make CPFP more reliable when fee pressure is high.

References

• Bitcoin Optech: Child pays for parent (CPFP)