Labour election latest: Jeremy Corbyn spoke today on Labour policy
Labour was accused by the respected Institute for Fiscal Studies of pretending it could raise the extra billions its plans required just by taxing big business and the "rich".
The thinktank's analysis of Labour's election manifesto said it implied state spending rising to its highest level since the mid-1980s and the tax burden climbing to a record peacetime high.
Conservative Chief Secretary to the Treasury David Gauke commented: "This is a devastating analysis of Jeremy Corbyn's manifesto.
"It is simply not worth taking the risk of him being in charge of our economic security and Brexit negotiations just 11 days after the election.
"Taxes would rise to their highest ever peacetime level if Jeremy Corbyn gets into Downing Street.
"Ordinary working families will be the ones who pay the price – not the top 5 per cent as he claims.
"His plans will increase the cost of living and hit wages.
"He is taking a gamble with youth unemployment and people’s pension pots.
"And he is not being transparent about how his plans will hit ordinary working families."
Presenting the IFS verdict on the two main parties' manifestos, deputy director Carl Emmerson said: "What Labour want you to hear is that the spending increases they propose pretty much across the board – on childcare, schools, health, welfare and the rest of it – would be funded by tax increases that solely affect the rich and companies. This would not happen."
Labour's manifesto set out spending commitments worth £48.6billion, with plans to raise the same in tax including by reversing Tory corporation tax cuts and raising tax on earnings over £80,000 a year.
But the tax hikes stated would raise no more than £40 billion at most in the short run and much less in the longer run, said the IFS.
Taxing business was not "victimless", with higher levies for firms likely to result in lower wages for workers or higher prices for customers as well as hammering pension schemes and undermining the economy generally.
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A case could be made for a bigger state but it should be done honestly, "not by pretending that everything can be paid for by someone else”, said Mr Emmerson.
"If they were to embark on these spending increases, some increases in taxes other than those mentioned in the manifesto would look likely.
"A state of the size the Labour Party would like would require broad-based tax increases."
The IFS also warned that raising the minimum wage as Labour proposes to at least £10 by 2020 was a "gamble" that could impose significant costs and risk jobs.
Labour's prospectus suggested that "we can have pretty much everything – free higher education, free childcare, more spending on pay, health, infrastructure – and the pretence is that it can all be funded by faceless corporations and 'the rich'", said Mr Emmerson.
But: "Labour aren't merely asking for a bit more from the top 5 per cent while leaving ordinary households alone. "There is no way that tens of billions of tax rises they promise can be borne entirely by such a small group."
The IFS also chastised the Conservatives for failing to address longterm challenges or be wholly frank with voters about what their plans mean.
The Tories' manifesto signalled yet another five years of "austerity" that could seriously damaging public services.
Cutting net immigration to the Tory target of "tens of thousands a year" risked a £6billion hit to the national coffers and could undermine the economy particularly when Britain's own population is ageing.
Theresa May's plans to means-test the pensioner winter fuel payment and scrap the triple lock state pension annual rise guarantee would make only "wholly trivial" savings, said the IFS.