Banks here have quietly raised the already high interest rates that apply to credit card bills.
In September, DBS Bank lifted the interest rate on outstanding balances from 24 per cent to 24.9 per cent.
OCBC's rate rose from 24.96 per cent to 25.92 per cent.
United Overseas Bank (UOB) raised its interest rate from 24 per cent to 25 per cent on Nov 22.
For years, cardholders who did not pay their bills in full by the due date have been charged interest of about 24 per cent on the outstanding amount.
Now, consumers have to foot higher interest charges.
It has been more than five years since OCBC last adjusted its rates, while UOB noted that interest rates had not been revised in the last decade.
A UOB spokesman said: "UOB does a periodic review of the interest rates it charges and makes adjustments according to market conditions when appropriate."
Mr Anthony Seow, head of cards and unsecured loans at DBS Bank Singapore, said: "DBS adopts a transparent rates and fees structure, which is readily available on our website, product highlight sheet... Our card charges are also aligned with industry standards."
While many customers pay their bills in full to avoid interest charges, those who make partial repayments are affected.
Outstanding balances are also subject to a minimum charge per month.
UOB has hiked this from $2.50 to $3 per month as well.
Cash advance interest rates have also risen at various banks.
Interest rates and charges are set by the industry and not prescribed by the Monetary Authority of Singapore (MAS) rules, while interest rate changes are seen as commercial decisions.
CIMB Bank revised cash advance interest rates to 28 per cent in October; DBS and UOB raised theirs from 24 per cent to 28 per cent in the last two months.
CIMB said it was the first revision since its credit card operations were launched in September 2009.
"It was after much consideration that we revised the rates and we did so due to increased costs and loss from the higher-risk group customers," said Mr Srihari G. Sikhakollu, managing director and head of credit cards and personal financing at CIMB Bank Singapore.
These higher-risk consumers could include some 1,509 people who sought help from Credit Counselling Singapore (CCS) in the first eight months of the year.
CCS noted in a recent report that this was up from the average of 650 a year from 2004 to 2008 and 1,377 a year from 2009 to last year.