Does anyone know anything about Capital gains tax on second homes?

[Fairslice]

My MIL owns a house next to her main house. It was built in the 50s (it's a small bungalow). She is thinking of selling. Obviously we'll ask professionals, but just wondered how they work out capital gains tax? If it's worth 175k now but cost 8k in the 50s would she pay tax on 167k? As that's likely to be 39% after the budget
Thanks.

No Idea what the rates will be after the budget until it's announced but I believe you will need to use the value as at 31 March 1982 to calculate CGT. There's info on the government website and a calculator. You would deduct costs of selling and improvements made from CGT liability.