The poor have been hit almost twice as hard as the rich by tax-and-benefit changes since the Tories came to power, independent experts say.
Low income households have lost out most from these changes overall - especially those with children.
The poorest 10% of households have seen losses of 7% of their income (£800 per year) as a direct result of these reforms; among those with children the figure rises to 18% (£3,800).
In contrast, the highest-earning 10% of the population have seen their incomes fall by only 4% since the austerity programme was introduced.
Pensioners have been “broadly protected” since 2010 with above-inflation increases in the state pension– while working-age benefits have been cut sharply in real terms.
The over 65s have seen on average a 1-2% gain as a consequence of tax and benefit policies.
Although income tax has been cut due to a rise in the threshold at which it is paid those changes have mostly benefited those on a higher income.
But the IFS experts said the reforms had strengthened the incentive to work, with workers in poorer households in particular keeping more of an extra pound of earnings.
Pascale Bourquin, a Research Economist at IFS said: "The tax and benefit system has been subject to a large number of changes since April 2010, including large cuts to working-age benefits, state pension increases and direct tax cuts.
"But not everyone has reaped the gains or borne the burden of these reforms to the same extent.
"On average, those in the upper middle of the income distribution have benefited the most from personal tax and benefit reforms and the poorest households have experienced the biggest proportional loss.
"While pensioners have on average been little affected by these reforms, working-age households with children have lost out – especially low income ones, with the poorest 10% losing £3,800 per year on average."
