change address is an additional address inside a wallet, which u can create with a raw transaction with 2 outputs.

What I want to know is how does this change address interact with the (for a lack of words) "original" address, when sending money back to the "original" address.

Does the change address have a pre-written script which sends BTC back to "original" address?

2 Answers 2


There is no relation at all between the two addresses, except that they're owned by the same person/wallet.

At the protocol level, "change" does not exist. It's just another output (with a corresponding address), indistinguishable from normal "payment" outputs. It is your wallet that's creating it: it needs a place to send the remainder of a spent UTXO of yours that you don't actually want to transfer, so it creates a new address of its own (just like you'd do when receiving funds), and sends the remainder there. And it stays there, until there is a need to spend those funds. It could send them back to the same address, but this would be a serious privacy leak (it lets people distinguish change from payment), and have no cost advantage.


It doesn't interact with the "original address". It's just another address in the wallet. The wallet keeps track of all of its addresses, receiving and change.

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