In Labour’s case, the think tank believes the party has been over-optimistic in its estimations for its expected tax take. The party expects to generate £53bn through tax rises, with £19.4bn derived from corporate tax rises; £3.8bn through an efficiency review of corporate tax reliefs; £8.8bn through measures against tax avoidance; £5.6bn through its ‘Robin Hood tax’ on high-frequency trading; £7.7bn through income tax and its proposed excessive pay levy; and a further £7.2bn through other means.

The IFS maintains that while Labour has factored in £4bn of ‘headroom’, it is more likely to collect closer to £41bn in the short term, and less in the long term.

Approximately £3bn of that is due to an error it made in its anti-avoidance package, double-counting the impact of its planned corporation tax rise and using the wrong figure from the Office for Budget Responsibility.

The remaining £8bn the IFS dropped from Labour’s expected take is comes from the central estimate of revenues from excessive pay levy and offshore company property levy coming closer to £0bn, and; a lower central estimate of revenue from the income tax rises.

‘For Labour, we can have pretty much anything,’ said IFS deputy director Carl Emmerson said in a manifesto press briefing in Westminster. ‘Free higher education, free childcare, more spending on pay, health and infrastructure. And the pretence is that can all be funded by faceless corporations and “the rich”.

‘But that comes at the cost of higher taxes which would inevitably be borne by large numbers of us. Labour are not merely asking from a bit more from the top 5% while leaving “ordinary households” alone. There is no way the tens of billions of pounds of extra tax rises they promise would be borne entirely by such a small group. If only policy making were that easy.’

As for the Conservatives, they offer the spending cuts already promised in the March Budget, the IFS said.

‘Compared with Labour, they [the Conservatives] are offering a relatively smaller state and consequently lower taxes. With that offer come unacknowledged risks to the quality of public services, and tough choices over spending,’ said Emmerson.

The IFS also criticised the Conservatives’ manifesto for its vagueness in several areas.

‘For the Conservatives, the big risk is that, after seven years of austerity, they would not be able to deliver the promised spending cuts either at all or at least without serious damage to the quality of public services. Their tight immigration targets would, if delivered, also damage the economy and the tax base,’ Emmerson added.