Tax return 2011 Form 12 page 6

Form 12 - Page 6 - item 17 - untaxed income arising in the state

re other investments - are An Post saving certs/Instalement savings reportable under this item?

Not familiar with them, but if you are talking about tax-free interest then I'd imagine it should be entered at Panel 31 "Exempt Income".

And bear in mind it's the interest income that you are reporting, not the amount invested or the balance.