What if your account opening balance is in overdraft state?
For example, opening balance is -5000, and allowed overdraft is 6000.
In that case real balance is 1000. Currently it is possible to see real state of account (-5000)
but it is not possible to see how much is left on account (1000).
Maybe you can add aditional value(allowed overdraft) when account is opened and than include
this in account status in sum(s).