You track it in your shared expenses app (e.g. Splid). When you enter an expense, you enter the amount, a description, and the persons in the group who are spli

You track it in your shared expenses app (e.g. Splid). When you enter an expense, you enter the amount, a description, and the persons in the group who are splitting that expense. For example, let’s say Anna, Bill and Josh start a group. Anna buys groceries, so she enters the following transaction: 30 EUR, groceries, paid by Anna, applies to {Anna, Bill, Josh}. Then, Anna, Bill and Josh can all see (on their own phone) that transaction in the transaction log, and they can also all see that Anna’s balance is 20 EUR, and Bill and Josh both have a balance of -10 EUR. Then, let’s say Bill and Josh go for coffee, Bill enters: 10 EUR, coffee, paid by Bill, applies to {Bill, Josh}. Then the balances become: Anna 20 EUR, Bill -5 EUR, Josh -15 EUR. So the nice part is that because everything is synced, everyone in the group can easily add transactions and see the transaction log and balances, all from their own phone.