Assuming the €200K was used to purchase the apartment (and some of it was not an equity release for other purposes) then you can offset interest on this against rental income when doing your rental income tax return. You can estimate the interest portion of repayments using Karl Jeacle's mortgage calculator. Remember that there are other potential implications (e.g. stamp duty clawback, need for non owner occupier insurance cover, PRTB registration (necessary to be able to offset mortgage interest against rental income), possible need to inform the lender etc.) to be aware of. There is also a key post in the Property Investment forum regarding having an interest only mortgage on a rental property to maximise the amount of interest that can be written off.