Not to worry Mick - We are here to straighten things for you!
You and you siblings can purchase any share of the home from your mother. However, on any share of the Property which now belongs to you after the purchase, your mother needs to pay a market rate of rent to you, otherwise another tax charge could be triggered. She could then be left to posess up to the nil rate band (Â£275k this tax year) of the property, which would avoid IHT.
To do this effectively however, your mother can invest the proceeds of sale in a Discounted Gift Trust. This will remove the capital from her estate. This will also giver her an income (tax free in certain cases) which she could use to pay rent on the portion of the property that belongs to you.
The Discounted Gift Trust would allow your mother to gift away the cash to you and your sblings through a Trust. You would not be allowed to touch the gift until the inevitable happened to your mother, but your mother would be allowed to take a tax free income FOR LIFE, from the gift she has made to you.
The result is that on starting the trust and making the gift, a considerable portion (e.g. 50% for a healthy 70yr old female) of the amount put into it would be immediately classed as outside the estate for Inheritance Tax purposes. After 7 years the whole amount is then outside the estate, and you have then avoided Inheritance Tax on complete gift. But of course your mother is still receiving the income for life which she can use to pay rent to you.
Be aware though that any value of the property she 'gifts to you' will be counted as a PET gift, which means she will need to live 7 years before it is removed form her estate, in addition to the requirement to pay rent to you.
If I can be of further help, please don't hesitate to contact me.
Investment and Inheritance Tax Planner
Zurich Advice Network
Contact no: 07957 440 724
e mail: firstname.lastname@example.org