SALE OF GOODWILL

My clients (limited company) are in the financial services sector i.e. placing clients money on money market and receiving commission from this - they are now selling the only asset of the business which is goodwill - the buyers are paying for the goodwill on a (fluctuating ) monthly basis over some 10 years - the valuation of the goodwill (as per the buyer) has been calculated on a "net present value based on average investor life" - this goodwill valuation will be recalculated at the end of each year based on monies paid (and payable) by the buyer . Does my client have to pay the CT on the goodwill valuation 9 months after the year in which it is sold? Also as the sale proceeds will be received over several years we will presumably need to prepare annual (non trading) accounts? In addition if the date of sale was moved into year 2 then would the CT on the sale of the goodwill be payable a year later?