Of course the UK doesn’t have any strict legal obligations simply because there is no strict legal code for the current situation. There are no mutually agreed criteria which would determine what the UK has to pay. Agreeing on such criteria is part of the process.
So yes, the UK could just drop out and refuse to pay anything. It is not hard to understand why this would be seen as an extremely hostile act: The UK was committed to pay a certain amount and just stepping back from all of that would undermine its credibility as international partner.
The UK roughly paid about €10bn each year to the EU (net). Asking for a number like 50bn would almost equal 5 years of full membership. Nobody should expect that the UK is going to accept this. Instead of focusing on a number, both sides should focus on each area and try to split this into a detailed discussion about different parts of the budget. In my opinion the UK should honor its commitments to any ongoing projects, but shouldn’t be forced to pay for stuff that just exist on paper.
I agree that we should. Calculating the exact figure is obviously tricky and I would err on the generous side.
It seems to me some people want both sides of the argument though.
On the one hand, we have agreed to the spending and shouldn't walk away. On the other hand, there are vast amounts of costs which are not in the spending agreements which somehow we have to pay our share of. When the figures being quoted start to get to 100 billion Euros and that's for a 12% share I can't believe anyone can take it seriously.
We are more than halfway through the budget round and will be almost completely through that round by the time the UK leaves or possibly even into the next round if the UK enters transitional years.
I also wonder how we can get to a final figure without knowing what the final deal is as some of the ongoing costs are likely to be covered by ongoing charges for access to the single market or membership of Europol etc etc.
Does anyone know when the EU will publish a figure it says the UK owes?