When a trader i.e. Leasee has paid a premium they are only allowed a proportion of this as a deductible expense based on the property income assessment of the landlord divided by the life of lease. So why can’t you claim the full amount? I appreciate that the lessor will have only reflected the same amount with the rest is subject to cgi.
Tax is full of rules based on legislation enacted by governments – those rules could have been different if made by different people – my advice is don’t ask why but learn what is!! As regards this question a trader can only deduct allowable trading expenditure against their trading profit – they cannot deduct what is capital expenditure. Capital expenditure is deducted in deriving a chargeable gain on any subsequent disposal of the lease! The capital aspect of lease expenditure however is not in your syllabus.