Around a third of credit card holders have had to rely on their plastic to cover living costs during January, a survey reveals.
An estimated 34% of those who own credit cards had to make use of them to get through the long wait until January payday.
The Post Office also revealed that more than 40% of respondents had used their credit cards to pay for grocery shopping in the first few weeks of 2011.
While 11% said they had to borrow in January because of overspending at Christmas, 10% of credit card users had little option because of the longer wait between the December and January paydays.
Meanwhile, 33% of January's credit card users said they had to use their plastic to bridge the gap between their income and spending every month.
Half of those with a credit card expected to continue spending the same amount on it in 2011 as they did last year, while 7% predicted they would spend more, a third of whom forecast an additional £100 of outgoings a month.
But only 56% of people pay off their bill in full each month, with 7% estimating that it will take them more than three years to clear their debt.
Az Alibhai, head of credit cards at the Post Office, said: "January has been a tight month for many of us, especially with the long wait until payday, and we can see that many people are falling back on credit cards to ease the costs of day-to-day living.
"If the debt is managed sensibly and paid off quickly, this can be very effective. However, if you don't pay off the bill in full, it can be a pricey way to fund daily purchases."
Opinium Research questioned 2,102 people during January.