Brend's PM contract could leave the economy as big as 5.5% less in a decade than it would be if the UK resided in the EU, an investigation has been said.
And the cost of the public money could be as much as 1.8% of GDP, the study by the London School of Economics, King's College and the Institute for Visiting Studies said.
He was to send & # 39; blamed the introduction of new trade impediment and falling in migration.
The government said that the matter was "in our national interest".
The report, published by the United Kingdom's independent idea of Europe, is changing, and assumes that Britain will live in unioning practices with the EU by its president's consent but to # 39; leaving their single market, according to the "backup" settlement.
- Brexit costs £ 100bn in the United Kingdom & # 39; by 2030
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However, he said that there would be a consequence of regulatory obstacles to the commodity of goods and services.
He also stated that the agreement would result in a decline in free movement, and # 39; reducing both skilled and unskilled migrants.
Taken together, this would mean that GDP per capita would be 1.9% -5.5% lower by 2030 than if Britain were left in the EU – the vast range of people; show the "great uncertainties involved".
However, he said that this would rise to 3.5% -8.7% if Brexit had a non-design.
The study said that the reduction in per capita income would be comparable in Ireland to the UK, but for most EU countries. The losses are estimated to be around 10 times lower.
He also said that the economy would have a "huge economic impact".
"They would be far greater than any benefit due to reducing EU allowances," he said.
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Dr Anand Menon, director of the UK in Europe, said: "Indeed, this type of economic modeling must be addressed with due regard.
"However, our estimates give clear cooperation of the wide scale of the impact of the contract that has been decided by its president."
The study comes to a day after a commission commissioned by a Vote of the People, who wants a second referendum, that a & # 39; The company of Breeds PM left a poorer £ 100bn in the UK from about 2030 than in the EU.
The government spokesman said: "This business will protect our jobs and our economy and respect our referendum outcome.
"It delivers economic partnership with the EU closer than you enjoy, any other country, good for business and is our national interest."
Prime Minister Theresa May now wants to urge MPs in the UK Parliament to return their contract but, she could not get involved.
If MPs refused the contract, a number of things could happen – including leaving unanimously, an attempt to reorganize or general election.