<p>For nodes that maintain their own mempool there really are two &quot;UTXO sets&quot;, one that only considers confirmed transactions and one that also considers mempool transactions. UTXOs that are spent by a yet unconfirmed transaction can be spent in a different transaction, provided some rules are met (e.g. the transaction fee is increased, see <a href="https://github.com/bitcoin/bips/blob/master/bip-0125.mediawiki" rel="noreferrer">BIP125</a> for more details), in which case the previous transaction is replaced.</p>

CC BY-SA 4.0
2024-11-08T13:14:02.010Z
2024-11-08T13:14:02.010Z
Vojtěch Strnad
<p>Suppose A spends a UTXO of 5 BTC. The transaction is sent to the mempool. Will the 5 BTC UTXO be instantly deleted from the UTXO set? If no, can this UTXO still in the UTXO set be used to make another transaction? Can this UTXO be used while it is in the mempool (unconfirmed transaction)?</p>

<transactions><unconfirmed-transactions><utxo><mempool><utxo-set>
Is a spent UTXO immediately deleted from the UTXO set?
Ashank
# Is a spent UTXO immediately deleted from the UTXO set?

(Asked by: username_0 on 2024-11-08)

Suppose A spends a UTXO of 5 BTC. The transaction is sent to the mempool. Will the 5 BTC UTXO be instantly deleted from the UTXO set? If no, can this UTXO still in the UTXO set be used to make another transaction? Can this UTXO be used while it is in the mempool (unconfirmed transaction)?

**Tags:** transactions, unconfirmed-transactions, utxo, mempool, utxo-set


---

## 1 answers

### Answer by username_1 on 2024-11-08. Score: 5

For nodes that maintain their own mempool there really are two "UTXO sets", one that only considers confirmed transactions and one that also considers mempool transactions. UTXOs that are spent by a yet unconfirmed transaction can be spent in a different transaction, provided some rules are met (e.g. the transaction fee is increased, see [BIP125](https://github.com/bitcoin/bips/blob/master/bip-0125.mediawiki) for more details), in which case the previous transaction is replaced.


---

