Sticking to Labour's manifesto pledge and freezing income tax thresholds rather than raising income tax has hurt low- and middle-income earners, an influential thinktank has said.
Millions of these workers "would have been better off with their tax rates rising than their thresholds being frozen", according to the Resolution Foundation's chief executive, Ruth Curtice.
"Ironically, sticking to her manifesto tax pledge has cost millions of low-to-middle earners", she said.
Chancellor Rachel Reeves announced in her budget speech that the point at which people start paying higher rates of tax has been held. It means earners are set to be dragged into higher tax bands as they get pay rises.
The chancellor felt unable to raise income tax as the Labour Party pledged not to raise taxes on working people in its election manifesto.
But many are saying that pledge was broken regardless, as the tax burden has increased by £26bn in this budget.
The thinktank, which aims to raise living standards, welcomed measures designed to support people with the cost of living, such as the removal of the two-child benefit cap, which limited the number of children families could claim benefits for.
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The announced reduction in energy bills through the removal of as yet unspecified levies was similarly welcomed.
The chancellor said bills would become £150 cheaper a year, but the foundation said typical energy bills will fall by around £130 annually for the next three years, "though support then fades away".
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This budget won't be the last of it, Ms Curtice said, as economic growth forecasts have been downgraded by independent forecasters the Office for Budget Responsibility (OBR), and growth is a "hurdle that remains to be cleared".
"Until that challenge is taken on, we can expect plenty more bracing budgets," she added.
It comes despite Ms Reeves saying as far back as last year, there would be no more tax increases.
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