Via Tom, the EU case [just quoted, not endorsed]:
“financial settlement should be based on the principle that the United Kingdom must honour its share of the financing of all the obligations undertaken while it was a member of the Union. The United Kingdom obligations should be fixed as a percentage of the EU obligations calculated at the date of withdrawal in accordance with a methodology to be agreed in the first phase of the negotiations”.
Via the Telegraph, the British case:
Officials believe that the UK is entitled of £9billion worth of funds currently held by the European Investment Bank.
Separate analysis has suggested that the UK is entitled to a further £14billion worth of EU assets including property, cash and other investments.
Iain Duncan Smith, a Tory MP and former Conservative leader, said: “We have put into the place half a trillion pounds over the past 40 years which has never come back. That’s invested in all sorts of stuff there.
“We have intellectual property rights, physical investment in buildings, money in the European investment bank. We own a chunk of the EU, we don’t owe them any money.
“They are petrified that in two years time we will pull out and they will lose the second highest donor to the Budget.We should sweep that to one side and say honestly, these back of the envelope calculations do nobody any good.