Property interests

Our client already owns one half of a family holiday property acquired as two separate quarters on different dates and at different prices. No only or main private residence elections have been made (he lives mainly in another city centre flat that he owns). The holiday property is one big house and is now very valuable.

He now intends to buy a third quarter interest in the holiday property from his sister-in-law. If he does can he elect that this is to be his main residence for a couple of weeks then switch back to the flat to take three years’ growth on that quarter out of capital gains tax?

More to the point could he put the first two quarters into the issue and elect for them similarly?

We have experience of all this with whole properties but not with fractional shares. Does it...