Payment received at end of lease

Hi,

Looking for advice regarding a payment we received from our landlord when we moved out of our old premises to a new premises. As I understand it a rent free period is usually amortised over the life of a lease (per IAS 17?). However as this payment is related to the previous and not the new lease I don't think we can classify it as a 'rent free' period. Any advice on how to account for this payment in our annual accounts? Is it a one off windfall type of payment to be classified as 'other operating income' or is there a specific method of dealing with it?

All suggestions welcome.