Can I offset pdh mtg interest against rental income tax??

I have a mortgage from 2006 of €715k on My private dwelling home.

I also have an investment property with no mortgage.

Stupidly I should have at the time taken part of the mtg out on the investment property but was not aware at the time that this would have been of benefit to me.

If the mortgage on my pdh is secured by both my pdh and my investment property, can I offset my rental income tax against the interest I pay on my mortgage? Obviously considering I do not also claim interest relief on my pdh mtg.

Any help would be much appreciated.
Many thanks

The allowability of an interest expense against the income from the rental investment property depends on whether or not the money was employed i.e. was it employed in the purchase / improvement / repair of the investment property? If not then there's no interest deduction to be taken. From my reading of your post, the mortgage in question was taken out solely for the purchase of your home, but the investment property was also security for the loan in order to improve LTV... in which case there's no deduction to be taken against income from the rental property.

Have a read of the first page or so of this for clarification of Revenue's position: [broken link removed]

Not the answer I was hoping for but thanks so much for that.