A ‘reversionary’ lease is one where the term commences after the date of grant.
The effective date of a reversionary lease for stamp duty land tax purposes is the date of grant, not the date the term commences.
The threshold, rates of tax and exemptions to be taken into account are those prevailing at the effective date of the transaction (that is, the date of grant). However the start date of the lease is used for the purposes of discounting rents to net present value (FA03/SCH5/PARA3). This takes account of the fact that the lease is fully effective as at the date of grant, but that the term of the lease does not start until some point in the future.
This is in contrast to the treatment of an agreement to grant a lease in the future – refer to SDLTM10040.