Rachel Reeves was accused of "broken promise after broken promise" by Rishi Sunak after delivering Labour's first budget since 2010.
Mr Sunak was making what was likely to be his last appearance as leader of the Opposition in the House of Commons as he responded to the fiscal event.
The budget is set to raise £40bn in taxes, increase borrowing and also put up spending.
Follow latest: Biggest tax-raising budget since 1993
Responding to the budget, Mr Sunak said: "On the day that he took office, the prime minister said that he wanted to restore trust to British politics with action, not words.
"Well, today his actions speak for themselves with a budget that contains broken promise after broken promise, and reveals the simple truth that the prime minister and the chancellor have not been straight with the British people."
He pointed out that "time and again" his party warned Labour would "tax, borrow and spend" beyond what they promised in the election.
The former prime minister's broadside came after Ms Reeves herself attacked the legacy of Mr Sunak and the last Conservative administration.
She said the Tories "failed this country".
"Their austerity broke the National Health Service," she said.
"Their Brexit deal harmed British businesses - and their mini-budget left families paying the price with higher mortgages.
"The British people have inherited their failure."
The chancellor went on to repeat her claims that the last government "covered up" a £22bn black hole in spending and "spent three times over" the Treasury's reserves.
Ms Reeves quoted the Office for Budget Responsibility by saying the last government "did not provide" all the information.
This, the current chancellor claimed, means any comparison between's today's forecast and March's is "false" as the Tories "hid the reality of that public spending plan".
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Jeremy Hunt, the Conservative chancellor who delivered that budget, seemed to be saying "that's not true" while Ms Reeves made the point.
Mr Sunak said Labour had "fiddled the figures".
"They have raised tax to record levels," he said.
"They have broken their promises - and it is the working people of this country that are going to pay the price now."
He added that he understood Ms Reeves' "shameless political motivations" and why it "suits her to cook up a false justification for her agenda".
Mr Sunak claimed the £22bn figure did not appear in the OBR's report.
While this is correct - the figure is not mentioned apart from in reference to Ms Reeves' use of it - the OBR states that analysis from the Treasury covering extra government spending was not handed over ahead of Mr Hunt's March fiscal event.
The OBR said a "materially different" analysis of the Tory budget would have been given if they had the information.
But "it is not possible to judge now exactly how much higher" spending would have been as more analysis would have needed to be done at the time.
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