Franchise Exit Payment

I have a client who was part of a national Franchise. However he considered that he was receiving nothing from the Franchise and negotiated an exit at a cost of £15,000.

The Franchisor has subsequently gone into liquidation, with only 1/3rd of the exit agreement being paid.

I know the rules on initial franchise payments - spread over the period of the franchise to renewal, but where there is an exit payment I am unsure - capitalise with immediate write off in P&L? As client is a sole trader I presume no tax relief available?