CG70822 | Leases: granting of a lease: no premium paid on grant of lease
From HM Revenue & Customs · Capital Gains Manual
If no premium is paid on the grant of a lease, and provided that the grant of the lease was an arm’s length transaction, no chargeable gain will accrue.
However, if the landlord has incurred any expenditure allowable under TCGA92/S38 (1)(c) (incidental costs of disposal), see CG15250, in granting the lease, a capital loss equal to the amount of that expenditure will accrue.