Britain's wage-earners have taken a £5,000 pay cut in the past five years, according to government figures, suggesting ministers will struggle to engender a feelgood factor before the 2015 general election.

The figures published by the Office for National Statistics show wages and salaries for the middle fifth of non-retired households fell from £33,100 in 2007-08 to £28,300 in 2011-12. Over the same period original income, which is the income households get from employment and investments, fell from £37,900 to £32,600, while cash benefits rose from £3,100 to £4,600.

The figures will fuel the debate about living standards before the general election, and about whether the government has done enough to protect the typical wage-earner.

The figures confirm that the earnings squeeze pre-dates the 2007 recession, appearing to endorse Ed Miliband's claim that the link between wages and growth has been broken, one of his chief justifications for his willingness to intervene in the market. The report says: "While GDP per person continued to grow at similar rates between 2004-5 and 2007-8, growth of median household income slowed to a fifth of its previous rate in the years immediately before the start of the economic downturn."

The Treasury will be fervently hoping that it will be able to show the link has been restored in 2014, either because economic growth is so strong or because it has taken steps to make work pay with its welfare reforms.

But the figures also show that despite the big rise in personal allowances due to budget decisions by the Liberal Democrats and the Conservatives, median household income for the overall population has fallen by 3.8%, after adjusting for inflation, since the start of the downturn.

However, while the median income for non-retired households fell by 6.4% between 2007-08 and 2011-12, the median income for retired households grew by 5.1%.

Between 2007-08 and 2011-12, average income from employment and investments for the middle fifth of non-retired households fell from £37,900 to £32,600.

Cash benefits for the middle fifth of non-retired households rose from £3,100 to £4,600 between 2007-08 and 2011-12. As a result, the average proportion of gross income coming from cash benefits increased from 7.6% to 12.3% for this group.

Average direct taxes paid by the middle fifth of non-retired households have fallen from £8,700 in 2007-08 to £6,800 in 2011-12. As a percentage of gross income, this is equivalent to a fall from 21.1% to 18.3%.

Looking over a longer period between 1977 and 2011-12, the middle fifth of households saw an increase in unequivalised gross income from £18,500 to £30,100, after taking inflation into account.

The report confirms the extent to which the reforms have hit middle incomes, but also the way in which the retired have been relatively immunised, confirming there is an issue of inter-generational fairness to be addressed. The retired median household income is still much lower in absolute terms than non-retired income.

The Treasury countered the figures with its own report showing wage growth had followed GDP growth in the previous two recessions. It says that although wages have shrunk, this disguises the extent to which workers have been subsidised by higher company pension contributions or higher national insurance contributions.

The Resolution Foundation, a thinktank that specialises in this policy field, said: "It is striking that there was a pronounced slowing in the growth of median household incomes even before the years of economic downturn. It confirms that between 2004 and 2008 income growth slowed to a fifth of its previous rate, even as GDP growth kept up a consistent pace. This underlines Resolution Foundation work highlighting the major slowdown in wages and incomes that occurred well before the great recession.

"The figures also reveal a dramatic generational difference – with the incomes of working-age households falling by more than 6% since 2008 while those of retired households have continued to rise. The pre-crisis slowdown is likely to have been even starker if we looked only at working-age households."