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HMRC internal manual

Capital Gains Manual

Leases: merger: introduction

Where a leaseholder of land acquires a superior interest (either the freehold reversion or the immediately superior leasehold interest) in the same land, the earlier lease will be extinguished. The two separate assets, that is the original lease and the superior interest, are regarded as merged within TCGA92/S43 and the owner now has a single asset.