Quitting the European Union would leave households £4,300 a year worse off, George Osborne warned as he prepared to release in-depth Treasury analysis on the cost of Brexit.
Britain's economy would shrink by 6% by 2030 if the country replicated Canada's trading agreements as advocated by Boris Johnson, according to the Chancellor.
Video report by ITV News Deputy Political Editor Chris Ship.
George Osborne has today produced figures suggesting that every family could be thousands of pounds worse off outside of the EU.
The data, backed by the treasury research team, suggests that a vote to leave could cost £4,300 per household every year by 2030.
The figures were based on a trade deal with the EU similar to the one struck by Canada - and which has been praised by pro-Brexit rebel Boris Johnson.
The London Mayor was among those who dismissed the chancellor's figures as unreliable and incorrect.
"We've got a great future ahead of us," he said in response.
Vote Leave has so far said little about the Chancellor's gloomy predictions for Brexit, but Leave.EU thinks it's still a price worth paying.
The Treasury forecasts leaving the EU would leave households quite a lot poorer on average - between £2600 and £5200 a year in 15 years.
George Osborne's comments in The Times come ahead of a Treasury report on cost to the country of pulling out of the EU.