My question is if I can set the TXID in a raw transaction and send it after it with 'sendrawtransaction' (from the qt console)?

If not, is there a way to do it? And if there is a way, does it means I can send to the bitcoin network the same transaction id over and over again even if the transaction itself is different each time (different inputs or outputs).

  • I first thought I understood what you are asking, but upon reading this again, I think it would be helpful if you gave us more detail on what you are trying to accomplish.
    – morsecoder
    Mar 30, 2015 at 18:58

1 Answer 1


You cannot choose the TXID of your transaction, really. It is calculated by SHA256d hashing the serialized transaction bytes. If you did happen to get miraculously lucky enough to get a transaction with the same hash as a different transaction, then it would be refused by the network for attempting to overwrite a transaction.

There used to be a bug in bitcoin that coinbase transactions could have the same TXID sometimes. This was fixed by BIP34.

  • Re BIP34 I never knew that! Fascinating. I believe OP is confusing assigned TxIDs with UTXO TxIDs Apr 1, 2015 at 10:12

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