Although their may be all sorts of rationales adduced for calculating the sums due, the bottom line is that the figures are entirely negotiable and dependent of goodwill and other concessions made. The figure will be miraculously reduced if there is a deal on the table the EU actually wants, and kept high if they are dissatisfied with progress.

The ongoing annual payment for access to the Single Market may end up being of more significance.  Here there are Norwegian/Swiss precedents for guidance although none are binding. Presumably it will have to be less than current UK payments (less rebate) to the EU budget, but who knows?  It depends on how bloody minded the negotiations get, and how much both parties want the deal taking shape.

Index of Frank's Diaries