<blockquote>
  <p><strong>How can Bitcoin transactions be traced if you can change your address?</strong></p>
</blockquote>

<p>In Bitcoin you don't <em>change</em> your address. You create new receiving addresses. </p>

<p>This is normally done so that a new address is created for each new transaction with the intention to increase privacy.</p>

<p>However in each transaction there are inputs and outputs and if a transaction has one input and two outputs, if you can infer which output is change, you know that there is some connection between the input address and the output address. You may be able to then trace that connection further back through a series of transactions. This is approximately like tracing possession of a coin passing through a series of people or businesses in a series of transactions.</p>

<p>This becomes more difficult if transactions have much more than one input and much more than two outputs.</p>

<p>Transactions may have certain characteristics such as address-types, size, timing and so on that may make it possible to make inferences. Transactions with differing characteristics could be inferred as being different parties, those with similar characteristics might be potentially associated with a single party of interest.</p>

<p>For example, if you see a large transaction with hundreds of inputs and one high-value output occur every Friday at 19:00 UTC, you might suspect it was a large exchange moving funds into cold storage as part of it's regular operational procedures. The timing might suggest a specific timezone.</p>

<p>We know that organisations such as the FBI perform <em><a href="https://en.wikipedia.org/wiki/Blockchain_analysis" rel="nofollow noreferrer">blockchain analysis</a></em> to trace illegal activity. The details of their methods are not published, so far as I know.</p>

<p>See </p>

<ul>
<li><a href="https://bitcoin.stackexchange.com/search?q=blockchain+analysis">https://bitcoin.stackexchange.com/search?q=blockchain+analysis</a> which leads to</li>
<li><a href="https://bitcoin.stackexchange.com/q/95902/13866">How can there exist businesses that &quot;specialize in blockchain analysis looking for patterns of usage that reveal how money is being used&quot;?</a></li>
<li><a href="https://bitcoin.stackexchange.com/q/45651/13866">How can I find a digital forensics expert to help trace stolen bitcoins?</a></li>
<li>etc</li>
</ul>

CC BY-SA 4.0
2020-05-22T09:15:14.200Z
2020-05-22T09:23:52.367Z
2020-05-22T09:23:52.367Z
RedGrittyBrick
<p>Let me give you two examples:</p>
<ol>
<li>You want to send 3BTC to address 1abc... .  Your wallet uses for this transaction input address 1def... with balance 2BTC and input address 1ghj... with balance 2 BTC. On the output side you see address 1abc... with 3 BTC and 1pqr... with 1 BTC. Then it's very likely (not sure) for third parties that 1pqr is the change address belonging to the same entity as 1def... and 1ghj. This is because otherwise one input address would have been enough to do the transaction. For your next transaction 1pqr is spend together with 1stu... as common input. Even if you didn't re-use an address it's now likely that 1def..., 1ghj..., 1pqr... and 1stu are controlled by the same person. We linked addresses although they weren't re-used.<br></li>
<li>Tracing through a mixer transaction (e.g. wasabi): You have address 3abc.. and 3def... in your wallet and both addresses are likely known belonging to the same person (derived by analytical techniques like in 1.). Now you send 3abc through a mixer and your new address is 3ghj... . If now or later 3ghj ends in the same wallet as 3def and will be co-spend together then the mixer transaction privacy is revealed for 3abc. One of my peers recently traced a wasabi transcation and was able to link 22% of the output addresses to their inputs with this method.</li>
</ol>

CC BY-SA 4.0
2021-06-06T22:32:32.093Z
I like this explanation.  My question, what if the amount was emptied (0) after each use?
user1367323
CC BY-SA 4.0
2021-06-09T22:47:41.943Z
You mean a transaction without change address? You can do this but then you donate bitcoin if you  have not exactly the right amount to send (having the exact amount is very unlikely in an 8 digits currency). If I see this transaction I'd check if the output address is a deposit address of an exchange. Alternatively I'd assume you just consolidated or moved funds into the new address which is as well yours.
tempo
CC BY-SA 4.0
2020-11-17T23:31:23.920Z
2020-11-17T23:37:56.147Z
2020-11-17T23:37:56.147Z
tempo
<p>ethereum addresses are interchangeable just like bitcoin addresses, you can track bitcoin for example at blockchair.com and ethereum addresses at etherscan.io</p>

CC BY-SA 4.0
2020-05-22T08:13:03.347Z
2020-05-22T08:13:03.347Z
Eddy
<p>I understand in Ethereum you can trace it because wallet address never changes. But in Bitcoin you can change your address, no? Thanks.</p>

<traceability>
How can Bitcoin transactions be traced if you can change your address?
Tomas 
# How can Bitcoin transactions be traced if you can change your address?

(Asked by: username_0 on 2020-05-22)

I understand in Ethereum you can trace it because wallet address never changes. But in Bitcoin you can change your address, no? Thanks.

**Tags:** traceability


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## 3 answers

### Answer by username_1 on 2020-05-22. Score: 1 | Accepted answer

> **How can Bitcoin transactions be traced if you can change your address?**

In Bitcoin you don't *change* your address. You create new receiving addresses.

This is normally done so that a new address is created for each new transaction with the intention to increase privacy.

However in each transaction there are inputs and outputs and if a transaction has one input and two outputs, if you can infer which output is change, you know that there is some connection between the input address and the output address. You may be able to then trace that connection further back through a series of transactions. This is approximately like tracing possession of a coin passing through a series of people or businesses in a series of transactions.

This becomes more difficult if transactions have much more than one input and much more than two outputs.

Transactions may have certain characteristics such as address-types, size, timing and so on that may make it possible to make inferences. Transactions with differing characteristics could be inferred as being different parties, those with similar characteristics might be potentially associated with a single party of interest.

For example, if you see a large transaction with hundreds of inputs and one high-value output occur every Friday at 19:00 UTC, you might suspect it was a large exchange moving funds into cold storage as part of it's regular operational procedures. The timing might suggest a specific timezone.

We know that organisations such as the FBI perform *[blockchain analysis](https://en.wikipedia.org/wiki/Blockchain_analysis)* to trace illegal activity. The details of their methods are not published, so far as I know.

See

* <https://bitcoin.stackexchange.com/search?q=blockchain+analysis> which leads to
* [How can there exist businesses that "specialize in blockchain analysis looking for patterns of usage that reveal how money is being used"?](https://bitcoin.stackexchange.com/q/95902/13866)
* [How can I find a digital forensics expert to help trace stolen bitcoins?](https://bitcoin.stackexchange.com/q/45651/13866)
* etc


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### Answer by username_2 on 2020-11-17. Score: 0

Let me give you two examples:

1. You want to send 3BTC to address 1abc... . Your wallet uses for this transaction input address 1def... with balance 2BTC and input address 1ghj... with balance 2 BTC. On the output side you see address 1abc... with 3 BTC and 1pqr... with 1 BTC. Then it's very likely (not sure) for third parties that 1pqr is the change address belonging to the same entity as 1def... and 1ghj. This is because otherwise one input address would have been enough to do the transaction. For your next transaction 1pqr is spend together with 1stu... as common input. Even if you didn't re-use an address it's now likely that 1def..., 1ghj..., 1pqr... and 1stu are controlled by the same person. We linked addresses although they weren't re-used.
2. Tracing through a mixer transaction (e.g. wasabi): You have address 3abc.. and 3def... in your wallet and both addresses are likely known belonging to the same person (derived by analytical techniques like in 1.). Now you send 3abc through a mixer and your new address is 3ghj... . If now or later 3ghj ends in the same wallet as 3def and will be co-spend together then the mixer transaction privacy is revealed for 3abc. One of my peers recently traced a wasabi transcation and was able to link 22% of the output addresses to their inputs with this method.

> **Comments:**
> **username_3**: I like this explanation.  My question, what if the amount was emptied (0) after each use?  
> **username_2**: You mean a transaction without change address? You can do this but then you donate bitcoin if you  have not exactly the right amount to send (having the exact amount is very unlikely in an 8 digits currency). If I see this transaction I'd check if the output address is a deposit address of an exchange. Alternatively I'd assume you just consolidated or moved funds into the new address which is as well yours.  

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### Answer by username_4 on 2020-05-22. Score: -1

ethereum addresses are interchangeable just like bitcoin addresses, you can track bitcoin for example at blockchair.com and ethereum addresses at etherscan.io


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