More than 7% of adults will go into the red to pay for Christmas, with credit cards the most popular way of borrowing, a survey has found.
Four out of every 10 people will already have debts, on top of mortgages and student loans, when they start their Christmas shopping, it found.
Moneysupermarket.com commissioned a poll of 2,700 adults to find out their levels of borrowing.
The situation is the most acute in the South East of England, the poll said.
"We know times are tough," said Moneysupermarket's head of loans, Tim Moss.
"Our research shows that almost 20 million consumers will be heading into the most financially stressful period of the year already in debt."
Some 69% will put the cost of presents and festivities on credit cards, 23% will use overdrafts, and 8% will take out a loan.
The pressure appears to be strongest in the South East of England where one in five debt-free consumers are expecting to go into the red as a result of Christmas, the poll found.