Leading economists argue a Brexit would cost the UK government between £20 billion and £40 billion in lost funding by 2020.
The result would be prolonging austerity measures to balance the books by 2022, two years later than currently forecast.
The Institute for Fiscal Studies also corrected statements by Brexit campaigners suggesting Britain pays £350 million a week into European Union coffers.
The IFS revised the figure taking into account subsidies and rebates received by Westminster and put the figure nearer £150 million.
Investors will vote to leave EU
At least 56% of investors will vote in favour of a Brexit and one in five are already changing their investment strategies ahead of the June 23 vote, according to research by The Share Centre.
Most investors feel both referendum campaigns are ineffective, while 87% do not trust Prime Minister David Cameron as a spokesman for the European Union.
Close to a third revealed US President Barack Obama’s intervention made them more likely to vote to leave.
Nevertheless, many have serious concerns about how stock markets will react after the vote.
“A clear majority favour a Brexit,” said a spokesman for the firm.
“It seems they have a credibility gap with the big hitters on both sides and are prepared to go with the markets to vote to leave.”
Rents and home prices will fall on Brexit
Home values will tumble by £7,500 London and £2,300 across the rest of the country if Britain leaves the EU, says research by the Association of Residential Letting Agents (ARLA).
The drop will follow a decrease in the population of 1 million by 2026, easing the pressure on housing and lowering demand for buy to let property.
Most of the population fall will come from tougher controls on immigration – but this is a double-edged sword for the economy.
“While house prices and rents will fall because of less demand, fewer houses will be built because one in 20 construction workers come from the EU and bridge a skills gap in the UK. Without them, building houses will take longer,” said an ARLA spokesman.
Net migration rises to 333,000
The last official net immigration figures before the referendum were always going to be controversial, but they have played into the hands of the Brexit campaigners.
The statistics show 333,000 more people came to Britain than left last year. Around 184,000 were from EU countries and 77,000 came without jobs seeking work.
The rest were from outside the EU.
The figure was a net increase of 20,000 year-on-year.