Wasting assets: leases
Lease of land
The treatment of leasehold land depends on the length of the lease. Where a non-renewable lease is for fifty years or less, it is treated as a wasting asset. Where the lease has a renewal clause, the lease should be treated as being granted for the extended term (unless the rules in TCGA92/SCH8/PARA8(2) or (3)&(4) apply). If that extended term is fifty years of less, it is treated as a wasting asset.
CG70700+ tells you more about leasehold interests in land.
Leases of other assets
The predictable life of a lease of an asset other than land will depend on the terms of the lease. If it is clear that the lease has a finite life of fifty years or less, it will be treated as a wasting asset.
Where a lease is granted for a period of fifty years or less, but there is a renewal clause in the agreement, you should still regard this as a wasting asset. As the predictable life is based on the position as it was when the lease was originally granted, it could not be said with certainty that it would be renewed.