Should a person put Interest Received on the VAT201 under Output Tax as "Exempt/Non Supply"? The net effect of all interest (interest paid and interest received) is interest paid (ie. interest paid is more than interest received)

If it needs to be declared as "Exempt/Non Supply", but it hasn't been done...can one declare all interest received up to date (say March 2011 up to October 2011) in the next return that is due? Or should the returns already submitted be reopened for these periods?