(a) On 30 June 2024 Sam assigned the lease of a building that had been acquired as an investment for £60,000; the lease expires on 30 June 2040. He had acquired the lease on 1 January 2016. The capital element of the original cost (excluding amounts attributable to rent) was £12,000 and the building has never been used as his principal private residence.
For this what should I need to take cost to calculate the capital gain tax?