Hi.What HMRC mean by the phrase "you need to know the allowable expenditure remaining after the grant of the original lease" is nothing to do with regular expenditure of the type you mentioned in your question which you would have claimed against the rental income paid by the lessee. What HMRC are referring to is that part of the original cost of the freehold of the building that remained after a proportion, if any, of that expenditure was used in the calculation of the gain on the grant of any leases or on previous surrender payments including the lease being surrendered now, in the past. See CG71280 here. If none of any of the previous leases you have granted on this building allowed for an early surrender payment then you will be treated as having made a part disposal of your interest in the building on receipt of any lease premium or surrender payment and your original cost will have to be adjusted to take account of that part of the cost allocated to those lease premiums and surrender payments. In order to work out the gain on the surrender payment you are about to receive you should follow the answer I gave to one of your earlier questions here.I hope this helps but let me know if you have any further questions.