The starting balance in Float is called the ‘Total reconciled cash’ or ‘Total matched cash’ and is shown to the left of the main cash flow graph.
This figure is the starting point for Float calculating the future cash balance/position.
Float takes the starting balance and adds/subtracts your open invoices, your open bills and any forecasts you have created to generate an expected cash balance for future days, months and years.
The starting balance is also the start point for calculating the historical balances (the opening/closing balances for each past month).
For historical balances, Float takes your starting balance and works backwards, adding/subtracting all your reconciled/matched transactions to arrive at the previous balances.