There is a logical way that the bill could be calculated that is open and transparent. The amount the UK pays into the EU budget is known as a percentage of the whole budget very accurately. After deducting the administrative cost of running the EU, the EU spends its net budget through a variety of programmes. The biggest is the Common Agricultural Policy whereby farmers receive subsidies in accordance with a set of CAP rules. There are then a variety of other programmes that, for example, might help development of deprived regions, help develop better infrastructure, help to fund research and development etc. Each programme will span a number of years, have a set of aims and a set of rules that people/organisations must follow in order to qualify for funding. Projects are approved throughout the duration of the programme until all funds allocated for that programme are committed. Finally there is a commitment to pay pensions of EU staff, many of whom are UK citizens. So calculating the bill should be straightforward:
- 1 The UK should pay its share of the administrative bill up to the day of exit.
2 The UK should pay its share of CAP and receive subsidies from CAP up to the day of exit or possibly some other date that better reflects when subsidies are paid. For example if the EU accepts applications for subsidies in the autumn and makes payments by the end of January then the UK could agree to pay the CAP portion of the budget up to the end of January following the day of exit and farmers receive the full subsidies for that year.
3 The UK should pay its full share of all projects actually approved up to the day of invoking Article 50 even though some of those projects might go beyond the day of exit. Similarly UK Projects already approved up to the day of invoking Article 50 should receive their funding to the end of those projects even if it is beyond the day of exit. I suggest using the day of Article 50 rather than the day of exit for this calculation because of the risk that applications for project funding from the UK might receive less than favourable treatment after Article 50 was triggered.
4 The UK should pay an actuarially determined amount to cover its commitment to future pension payments up to the day of exit. Private and occupational pension funds do this calculation as a matter of routine for their annual reports so there is a well defined process.
5 An actuarially determined amount representing the share of EU assets that the UK has contributed to acquiring should be deducted from the above.
All the information for items 1 to 3 is available from the EU accounts. Items 4 and 5 can be determined by an international accountancy firm. It's possible there are items I haven't considered but they can be included in the calculation using the same logic. All those numbers should be accessible to the government so it could perform the calculation now and say what it believes the bill should be. At the moment various people seem to be waving their fingers in the air and spouting an arbitrary number.
PS I think you mean billion not million Brian or is your membership name disguising that you are really Diane Abbot?