Her leftovers used to go in the bin. Now they go in the fridge. Debbie Thompson has made scores of little savings since the credit crunch started to bite, but none more than in the kitchen.

Her leftovers used to go in the bin. Now they go in the fridge. Debbie Thompson has made scores of little savings since the credit crunch started to bite, but none more than in the kitchen.

"Last year if I made, say, too much mince, I would put what was left in the bucket," said the mother of two yesterday. "This year it has been going into Tupperware."

Ms Thompson, 40, a housing officer from Kirkcaldy in Fife, is one of just millions to see their disposable income fall, in real terms, for the first time in a decade. Yesterday an independent report worked out that the average UK household this year has £2500 less to spend after essential bills than in 2007.

That is no surprise to Ms Thompson, a single parent. Her weekly grocery bill has jumped from £60 to £80 in the past year. Her employer, Fife Council, like other Scottish local authorities, has offered wage rises of 2.5% this year, next year and again in 2010 - not enough, she believes, to keep up with inflation.

"Things are a lot more expensive," she said yesterday. "Gas is up, electricity is up, fuel for the car is up. We are going to have to make some real changes in our lifestyle. I have traded in a two-litre Peugeot for a 1.5-litre Renault, we have started to pick and choose bargains in the shops, going to Aldi as well as Asda. Last year we got away to the Dominican Republic for a fortnight. That won't happen this year."

Housing officers like Ms Thompson earn about £22,000, just under the Scottish average wage. "Things were good for a while there. We even moved to a bigger house two years ago. We have started to regret that. Our house is worth £10,000 less than when we bought it. We are going to have to make sacrifices to pay the mortgage."

The decline in average disposable incomes over the past year has been dramatic - and unforeseen. Ms Thompson described it as "coming out of the blue". For more than a decade the amount of money the average household had free to spend had went up, year after year. In the last 12 months, soaring bills, combined with low wage rises, have wiped out all the gains made since Gordon Brown became Chancellor in 1997. Household disposable income averaged at £17,102 in 2007. It is £14,520 this year. Inflation for essential living costs was 8% in the last year.

The former Chancellor - now Prime Minister - has squeezed disposable incomes directly. Research for the price comparison website uSwitch.com confirmed that taxes are up, too. They account for the highest proportion of gross income since 1991 - 21 per cent.

The poorest have been hit hardest. The number of households living below 40% of the national average income has jumped to 5.6 million in the UK, one in seven of the total and the highest level since Mrs Thatcher came to power in 1979.

Heating costs are among the worst. Norman Kerr, director of fuel poverty charity Energy Action Scotland, yesterday called for a long-term government effort to offset soaring bills for gas and power.

Some Scottish regions rank among the lowest for disposable income in the UK. The figure, for example, is under £10,000 in Glasgow and just over £11,000 in Orkney.

There is, however, some evidence that the crash in disposable incomes in Scotland may not have been as dramatic as in England. House prices, though far from immune to the credit crunch, have held up better north of the border. Retail sales, too, are bucking the UK trend.

Kenneth Low, chief economic forecaster at the Fraser of Allander Institute, said: "They have bigger wages and bigger bonuses in London and the south-east than we do. That's the upside for them. The upside for us is that we don't suffer the same troughs they do, they are much more volatile than we are."

Unions are mobilising to get wages up in line with the "real" inflation facing families. That, in turn, has scared the UK Government, which fears pay awards could further fuel inflation.

Ms Thompson joined Unison's nationwide strike last week. "I couldn't afford to lose a day's wages," she said. "But then I don't think I could afford to take a drop in salary for three years in a row either."