<p>Since the very beginning. Transactions have had the <code>nLockTime</code> field since Bitcoin 0.1.0.</p>

CC BY-SA 4.0
2020-05-17T02:01:13.290Z
Though interestingly, it worked differently until a soft fork. It used to be signed, and was changed to unsigned.
Claris
CC BY-SA 4.0
2020-05-16T19:55:12.690Z
2020-05-16T19:55:12.690Z
Ava Chow
<p>Since when lock time exist in Bitcoin transactions? </p>

CC BY-SA 4.0
2020-05-16T21:02:54.850Z
You may be thinking of the CLTV opcode (which allows putting requirements on the nLockTime of spending transactions), which was added in BIP65 (activated in 2013).
Pieter Wuille
CC BY-SA 4.0
2020-05-17T11:54:01.400Z
There was no mistake :)
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<transactions><bitcoin-core-development><unconfirmed-transactions><history>
When "lock time" was added to Bitcoin?
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# When "lock time" was added to Bitcoin?

(Asked by: username_0 on 2020-05-16)

Since when lock time exist in Bitcoin transactions?

**Tags:** transactions, bitcoin-core-development, unconfirmed-transactions, history

> **Comments:**
> **username_1**: You may be thinking of the CLTV opcode (which allows putting requirements on the nLockTime of spending transactions), which was added in BIP65 (activated in 2013).  
> **username_0**: There was no mistake :)  

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## 1 answers

### Answer by username_2 on 2020-05-16. Score: 4 | Accepted answer

Since the very beginning. Transactions have had the `nLockTime` field since Bitcoin 0.1.0.

> **Comments:**
> **username_3**: Though interestingly, it worked differently until a soft fork. It used to be signed, and was changed to unsigned.  

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