I have seen a tx A get replaced by a tx B, where B had a lower fee and feerate than A and it was broadcasted later. How is it possible?

These are the txs details:

  • Tx A: segwit, ̶t̶a̶p̶r̶o̶o̶t̶, ̶R̶B̶F̶
  • Tx B: segwit, ̶t̶a̶p̶r̶o̶o̶t̶, ̶R̶B̶F̶, Full RBF

Can anyone help me understand it, please?

  • 2
    Could you share the transactions you're talking about? Commented May 17 at 12:23

1 Answer 1


Generally, the replacement rules employed by Bitcoin Core specify that a replacement must both exceed the original transaction in feerate as well as in absolute fees.

A likely explanation could be that while your node saw the higher feerate transaction first, the miner that found the block had seen the original, lower feerate transaction first and when they authored a block, you learned about the lower feerate transaction from the block. Another reason could be that the winning transaction was accompanied by a child transaction which overall made parent and child more attractive than what you considered the better transaction.

These are only guesses, and there are a number of other scenarios in which a partial view of the overall situation could look like what you describe. If you want a more specific answer, please share the transactions in question.

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