Families were £15 a week worse off in November compared with the same month last year, according to Asda’s latest income tracker research.
The Leeds-based retailer said the average UK household had £161 of weekly disposable income during November, down 8.4 per cent on last year.
The cost of basic goods and deteriorating employment conditions were blamed for the pressure on family spending power.
Annual growth in the cost of basics fell to five per cent in November, the second consecutive slowdown in the cost of living.
Asda said that although the cost of food and clothing has seen an improvement, budgets are being squeezed by the rising costs of running a family home.
In October, gas prices were 25.3 per cent higher than a year ago, while electricity prices grew by 15.5 per cent.
Transport costs continue to put pressure on the inflation rate, with the cost of getting around a large driver of the headline rate of CPI inflation.
Figures from the AA show the cost of unleaded petrol grew by 12.3 per cent over the year to November, while diesel prices increased by 14.6 per cent.
Asda said a weak jobs market is increasing the pressure on family budgets. The unemployment rate remained at 8.3 per cent during the quarter to October.
There are fears that unemployment could rise to 8.7 per cent in 2012 after forecasts indicated that the public sector is likely to lay off more workers than previously thought.
Research consultancy Cebr is predicting that the amount of disposable income available to UK families in 2012 will stabilise.
It predicts a fall of £11 per month in December and £8 a month in January.
Charles Davis, managing economist at Cebr, said: “Difficult times are set to continue for British households, as economic fallout from the on-going debt crisis in the eurozone takes its toll on employment and wage growth prospects in the UK.”
Andy Clarke, Asda’s chief executive, said: “While November’s fall in the cost of living gives us optimism for 2012, fears over job security underline that for some families, times are challeng- ing.
“Business leaders should view this as a call to action by doing what British business does best – finding new ways to remove unnecessary costs.”