Consequences of exempted income not shown in belated return

Exempt income is just that - Exempt.  Even then, it is desirable to show the same in your returns.  Firstly, the Department may feel that the income is not exempt at all.  If it disclosed by you, then at least you can argue that there was no concealment.  If they find out themselves, then it becomes difficult to prove that no concealment was intended.  Secondly, by showing that income you can show that as the source for future investment.

You can file another return if possible (though it cannot be strictly called as revised return as the total income remains the same).