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What is a change address?

If you’re new to Bitcoin, you might be confused when you send a transaction and see that your address is empty afterward, even though you only sent part of your funds.

Don’t worry—your remaining funds were simply sent to a new address! This is called a change address.

A change address is where the remaining balance of a Bitcoin (or other UTXO-based cryptocurrency) transaction is sent.

Change addresses enhance your on-chain privacy, making it harder for third parties to track your spending.
 

To understand change addresses, it’s important to first learn about UTXOs. For more details, read our article: What is a UTXO?


How do change addresses work?


When you send one or more UTXOs to another address, you will receive some Bitcoin back to a change address which your wallet controls —unless you send the entire balance of those UTXOs.

Your wallet automatically creates a new, unused address and sends the remaining Bitcoin there. This address is not linked to your existing addresses.
 

Satoshi Nakamoto did not originally include change addresses in the Bitcoin protocol when it launched in 2008 but added them in a 2010 update.


Privacy and security benefits of change addresses


Lets take a look at a practical example.

Imagine your wallet has one UTXO worth 1 BTC, and you decide to pay 0.3 BTC for a product or service.

Your wallet will send 0.3 BTC to the recipient and 0.7 BTC (minus transaction fees) to a new change address that it controls.

When analyzing the blockchain, it’s harder to tell whether you sent 0.7 BTC or 0.3 BTC, adding a layer of privacy.

However, in some cases, a change address may be identifiable—for example, when sending to a different address format. This is because your wallet always returns change to an address in the same format as the original sending address.
 

Change addresses do not guarantee that your funds cannot be tracked on the blockchain - they just add an extra layer of privacy which makes it harder.


Change addresses in Trezor Suite


Trezor Suite automatically generates change addresses and sends the remaining funds when you make a transaction. It selects the necessary UTXOs and sends the specified amount to the recipient. Any remaining balance is sent to a newly generated change address in your wallet.
 

Trezor Suite’s Coin Control feature allows you to select which UTXOs you want to use, although this is a feature for advanced users only.