According to Defaqto, people who postpones repaying their credit card debt on a sum as little as £100 could be paying anywhere between £5 and £28.33 for their delay.
David Black, Defaqto’s head of banking, said: “Annual fees will more likely be introduced for people who pay off their balance every month rather than for those who carry debts.
“Those who have debts on their cards are more easily targeted by an increase in interest rates.”
Earlier this year, the Office of Fair Trading imposed limits on how much lenders could charge as “fees” for late payment of credit card debt.
Mr Black also pointed to an American habit of lenders charging borrowers who default on their credit card debt higher interest charges, prompting fears that this could spread here.