Why does my bitcoin address keep changing?

Your bitcoin address keeps changing because your wallet is designed to give you a fresh address for every payment. This is a privacy feature. The new addresses all belong to the same wallet, so nothing is lost when the one on screen changes.

Why does a bitcoin address change?

Every bitcoin transaction is public. The original 2008 white paper said that, since the ledger is open, privacy depends on keeping the link between addresses and people hidden. It recommended a new key pair for each transaction so that payments cannot easily be connected to one owner.

Wallets still follow that advice. The Blockstream app explains that a single reused address would make your payments easier to trace and your balance easier to estimate. Bitkey says it creates a new receiving address each time you open the receive screen, even if the last one was never used.

There is a second reason addresses appear. When you spend bitcoin, the white paper describes a transaction with two outputs, one for the payment and one returning the change to you. That change goes back to an address you control, which is another reason a wallet can list addresses you never handed out.

One wallet can hold all these addresses because modern wallets are hierarchical deterministic, or HD, wallets, a design set out in BIP 32 in 2012. They derive a whole tree of keys from one seed, the starting secret behind your seed phrase. That one backup covers every address the wallet will ever create.

BIP 32 also lets a business generate fresh addresses for each order without keeping private keys on its web server. Before HD wallets, the Bitcoin Wiki notes, new addresses could leave older backups out of date and put funds at risk.

Do old bitcoin addresses still work?

Generally, yes. Blockstream says funds sent to an earlier address arrive normally and stay accessible, because every address belongs to the same wallet. Its app simply does not reuse them by default.

The Bitcoin Wiki adds a caution. If the data for an old address has been lost or discarded, later payments to it may not be recoverable.

Can you reuse a bitcoin address?

Technically you can, but the Bitcoin Wiki, a community reference, advises against it. It says reuse links all of an address's payments together, exposes the people who paid you, and makes blacklisting easier. Each spend also adds another signature from the same key, and past software flaws have let attackers recover private keys in such cases. More on how addresses are followed is in can cryptocurrency be traced.

Why does Cash App's bitcoin address change?

We could not confirm a detailed public explanation from Cash App itself. Cash App is run by Block, which also makes the Bitkey wallet that Cash App promotes for self-custody, and Bitkey says it rotates addresses as a privacy feature. The general reasons above apply to most bitcoin apps. For how addresses look and work, see what is a wallet address.