Change address

In the UTXO model, each input must be spent in full. When there is a remainder after paying the recipient and the transaction fee, it is typically returned to an address controlled by the sender, called the change address, usually generated automatically by the wallet; some wallets return change to an address used previously. Transactions without a change output may represent an exact payment or a transfer of the full input value, less fees. Distinguishing change from payment outputs is central to tracing, but becomes less reliable in transactions involving multiple participants or recipients, such as CoinJoin and PayJoin transactions. Change identification is a heuristic and should be reported with its basis.