Jeremy Hunt has been accused of trying to “hoodwink” voters as his Autumn Statement unravelled within minutes of him delivering it.
The chancellor boasted that he had announced “the biggest package of tax cuts since the 1980s”.
He reduced the National Insurance rate paid by workers from 12% to 10%, while also unveiling cuts to business taxes.
But the independent Office for Budget Responsibility’s own assessment of the chancellor’s plans revealed that while the overall tax burden will initially come down, it is soon set to soar.
That is because of income tax thresholds remain frozen, meaning millions of workers end up in a higher tax bracket as their wages rise - a process known as “fiscal drag”.
The OBR said: “Tax changes in this autumn statement reduce the tax burden by 0.7% of GDP, but it still rises in every year to a post-war high of 37.3% of GDP by 2028-29.
“Income tax increases explain most of the increase in this forecast ... driven by threshold freezes and strong nominal earnings.”
As a result, the Treasury will rake in an extra £201 billion in tax over the next six years - four times more than the cost of Hunt’s cuts to National Insurance payments.
Lib Dem leader Ed Davey said: “This Autumn Statement was a Hunt hoax.
“Buried in the small print is a massive stealth tax raid that will drag millions into paying a higher rate in the coming years.
“The British people will rightly be furious at this deception, as they are forced to pay the price for Conservative chaos through years of unfair tax hikes.
“It is high time that this Conservative government came clean about just how much money they are taking out of hard-working families’ pockets.”
The OBR also downgraded its forecasts for economic growth over the next few years.
It also said that inflation will fall to 2.8% next year, well up on the 0.9% they forecast in March.
Labour’s shadow chancellor Rachel Reeves said: “After 13 years of the Conservatives, the economy simply isn’t working. And, despite all the promises today, working people are still worse off.”