The average household in the UK now owes a record amount of £12,887, even before mortgages are taken into account, according to the TUC.
Its research was based on figures from the Office for National Statistics (ONS) for the three months to the end of September 2016.
According to the ONS, total unsecured debt hit an all-time high of £349bn at that point.
The TUC divided that number by the total number of households in the UK.
However, its figures are inflated by the inclusion of student loans, which have increased rapidly over the last couple of years.
Last week’s figures from the Bank of England, which exclude student loans, put the total at £192bn up until the end of November 2016.
That is the highest figure since December 2008, but not a record.
Nevertheless, officials at the Bank have indicated they are not that worried about debt levels at the moment.
“Interest rates are still very low, and are expected to remain so for the foreseeable future, so there are fewer concerns on debt servicing than there were in the past,” said Andy Haldane, the Bank’s chief economist, last week.
“There are reasons not to be too alarmed about it ticking up, but it is absolutely something we will watch carefully,” he said.
But others believe many households could run into financial difficulties this year.
“The majority of borrowers will currently be able to cope with this extra debt,” said Joanna Elson, chief executive of the Money Advice Trust.
“However, if the economy does indeed suffer in 2017, this borrowing could become more difficult to repay – and some households risk finding themselves exposed to sudden changes in financial circumstances.”
The TUC said that unsecured debt as a percentage of household income had now reached 27.4%, the highest figure for eight years.
And it claimed that weak growth in wages had left more families reliant on borrowing.
“These increases in household debt are a warning that families are struggling to get by on their pay alone,” said Frances O’Grady, the TUC’s general secretary.
“Unless the government does more for working people, they could end the New Year poorer than they start it.”
The exclusion of student debt from the figures makes a significant difference to the total amount of unsecured debt, which refers to borrowing through credit cards and loans, including finance for new cars.
Students who began studying in England in 2012 are expected to leave university with debts of almost £40,000, according to a House of Commons Library paper published last month.