Money has long been the subject of the most ferocious political fights in Brussels and the Brexit divorce and Britain's legacy bill of as much as 20bn is shaping up to be one of the most epic of them all.
At the heart of the debate is a question about the nature of the bloc. Is it a club where a member's liabilities expire on withdrawal or one where a member honours its promises even after it leaves?
For the EU-27 the answer is clear. One official compared it to Britain signing a five-year gym membership then asking for its money back after three. Another senior diplomat said it was like Britain "sitting at the restaurant, picking from the menu, then leaving before the bill arrives".
Over time this has built up into a roster of outstanding payment promises known in Brussels by the French term reste liquider running to more than 200bn. It could increase to 241bn by 2019. With Britain's planned departure, it forces a financial reckoning that politicians had imagined would never be needed.
These are not the only liabilities. The EU accounts detail more than 300bn in shared payment liabilities, from fisheries agreements to pensions to promised funding for satellites building.
On top of that are about 56bn of shared contingent liabilities where the EU raised funds to lend to countries such as Ireland, Portugal and Ukraine and 21.4bn of loan guarantees that may generate costs in years to come.
Britain may argue it is no longer legally liable. It could be right. But the settlement will come in a political negotiation to leave the EU, not in a court.
The crucial point is that the EU is preparing to make payment of Britain's legacy bill a basic condition of securing single market access or a transition agreement, which would provide a soft landing for British business operating in Europe.
https://mishtalk.com/2016/10/13/eu-seeks-e20-billion-divorce-settlement/