What happens to surplus income and where is it added to?

It depends on whether a cash asset has been recorded.  If there is one, EVPro will add the surplus income to the first asset in the 'Order of withdrawals from assets' - found in the 'Preferences' section. If there is no cash asset, then it will, behind the scenes, create a cash account (Savings) with no charges and the surplus will be added into here.  You will then see reference made in Plan overview on the Potential journey to Savings.