Five million workers are to be hit by tax rises within weeks that will cost them hundreds extra a year.
It comes as millions of UK households are already battling a cost of living crisis which is forcing some to choose between heating and eating.
From April, National Insurance Contributions will go up by 1.25 percentage points, costing the average worker hundreds of pounds more a year.
At the same time, income tax bands are being frozen, meaning workers are effectively taking a pay cut.
Soaring inflation is pushing up the price of everything from energy bills to groceries.
A new energy price cap will come into effect in April, adding £693 a year to the average household bill.
And millions of workers are now set to be hit by a so-called “stealth tax bombshell”, which will reduce their take home pay by hundreds.
The Centre for Economics and Business Research (CEBR) has warned that more than nine million workers will pay more because of the tax freeze.
Five million lower-paid workers could have to pay income tax for the first time as a result of the measures.
And another four million workers will be dragged into the higher income tax bracket, which will see them pay 40% tax on their earnings.
The CEBR and others have called on the government to reverse its decision over the taxes.
But the Chancellor confirmed last month that it would go ahead with the measures.
The think tank said the freezing of tax allowances and “bad forecasting of inflation” meant the number of people paying the higher rate of income tax will almost double to 8.1million.
The move will raise £40billion for the government coffers, the CEBR said.