Have inherited a 25% share in a house worth £400k. I am considering retaining my share and another relative is looking to buy the other 3 people (£300k) out. So my existing £100k share would remain as an investment for me but the house would be main sole home of my other relative. How is the SD calculated? I already own my own home - so my share could technically be classed as a second home or BTL (although I am not planning to charge rent to my relative. Do I have to pay SD on the 100k share that I already own if/when my relative buys the other share?