The firm questioned over 2,000 people aged 18-55 for its latest Family Finances Report.
Debt was £9,314 in May but has since risen to £10,563 with the most common forms being debt on credit cards, personal loans and overdrafts.
Households with one child had the highest levels of debt with £15,848 followed by those with two or more children who owed an average of £11,739.
Single parents had the least debt with £5,505 but were most likely to use credit cards.
Families were typically spending £141 on debt repayments, up from £114 in May, but the report questioned whether people were making higher repayments yet still borrowing more.

Total family savings dropped from £1,228 in May to £1,131 but remain higher year-on-year. For families in London, the figures were dramatically higher with average savings of £5,092. Those in Wales had the lowest savings pot of only £436.
The average amount saved each month was £29, significantly down from May where the average amount was £45.
Worryingly, the number of families with no savings rose from 24 per cent to 28 per cent and the number of families who were saving nothing each month rose from 36 per cent to 37 per cent.
Isas were the most popular savings option with 36 per cent of respondents saying they used one, followed by Premium Bonds.
Looking ahead to 2013, fears about the costs of necessities and inflation have fallen but economic uncertainty meant many were worried about redundancy and unexpected costs.