It puts the true cost of Brussels rule at £980million – almost treble the disputed figure of £350million quoted by Boris Johnson in the referendum campaign and displayed on the side of the Vote Leave battle bus.
The revelation came as British and EU negotiators began the sixth round of Brexit talks in the Belgian capital yesterday.
And it was welcomed by Eurosceptics who said it showed why we need to leave the European Union as quickly as possible.
With Brexit Secretary David Davis and chief EU negotiator Michel Barnier due to meet today, the Government last night underlined its commitment to Brexit with a plan to include an exact time and date when Britain will leave in the EU Withdrawal Bill – 11pm British time on March 29, 2019.
The study on the costs of EU membership, by leading City analyst Bob Lyddon, strongly supports the view of Brexit campaigners that the UK should not pay the EU a big divorce bill of up to £78billion.
Mr Lyddon’s analysis takes into account the money paid directly to the EU budget each week.
The Office for National Statistics says this is £267million once the UK’s rebate is paid back to us and money spent by the EU on projects here is included.
However, he has also added £12billion a year lost to the Exchequer through legal tax avoidance schemes which result from Britain being a member of the EU.
Multinational companies such as Google and Amazon run their finances through Ireland, Holland and Luxembourg and the only way these loopholes can be closed is by the UK leaving the bloc.
Mr Lyddon has also calculated that the annual net cost of EU migrants – once the tax they pay is deducted from benefits paid out – is £30billion a year.
His figure excludes tariff payments collected by the EU from the rest of the world, which will instead go to the Treasury when Britain is out.
There are also extra payments to the EU such as the £2billion given by British taxpayers to its foreign aid budget which are not officially designated as payments to Brussels.
Raising concerns about Theresa May’s plans to go for a transition period which ties Britain to Brussels for at least another two years, Mr Lyddon described it as a stab in the back for UK voters.
Senior Tory backbencher Peter Bone said: “This analysis is much closer to the real cost of our EU membership. Almost a billion pounds a week is serious money and obviously the sooner we are out of the EU the better.”
Eurosceptic Tory MEP David Campbell Bannerman said: “This report shows we actually needed three Vote Leave buses in the referendum campaign.
“This is money that is being diverted from the NHS, education, schools, defence and public services.
“We have the Budget soon and imagine what the Chancellor could do with an extra £10billion a year – let alone the £50billion that these figures suggest.”
Mrs May was reported last night to be ready to raise Britain’s £18billion “divorce settlement” offer to the EU in a bid to break the deadlock in the negotiations.
The EU insists the divorce bill must be agreed before talks can move on to trade deals, and UK officials were said to be working on a new financial pledge to help nudge the process forward at next month’s leaders’ summit.
Britain’s rumoured change in stance was said to follow a softening of Tory MPs’ hostility to paying Brussels any money, with some leading Eurosceptics suggesting a higher payment would be a “small price” to pay for independence and a good trade deal.