When she put it in your joint names, that was a gift of half the value to you. If you are registered as joint tenants, you will automatically inherit her half share when she dies, regardless of what is in her will. If as tenants in common, then it will depend on her will or next of kin if she dies without a will. If she relies on the fair deals scheme for nursing home care her half share of the house may be charged in favour of the hse, and you will have a year after she dies to pay it off. As a nephew, you are only entitled to a group B threshold,so currently 32500 from an aunt without paying CAT, but of course the prior gift will be taken into account and will reduce that threshold. Favourite nephew relief really only applies to a business/farm.