As this is not your parents home they may have to pay Capital Gains Tax on the increase in value of the property since they bought it. All transfers between closely related parties are deemed to have happened at full market value even though your parents are not charging the full value. Also if your parents die within 7 years the full value of the property less any payment made is added back to the estate to determine if Inheritance Tax is payable. This could mean double taxation. Consult a solicitor first.