Generally, the fewer years remaining on the lease, the greater will be the premium. Many other factors are taken into consideration. A surveyor specialising in valuations for statutory lease extensions will be able to advise on a range of valuations which will give you the starting figure for your claim. The Leasehold Advisory Service has an online lease extension calculator at www.lease-advice.org which can give you a rough indication of the likely premium. The premium will be valued as at the date of your claim.