Sharp falls in official and mortgage interest rates are not being passed on to credit card holders who are paying hundreds of millions of dollars in extra interest to the nation's big banks.
A breakdown of interest rates on cards over the past two years shows that interest rates on the nation's 15 million cards have barely moved.
In some cases rates have remained stable and annual fees increased as banks attempt to protect their bottom lines at the expense of credit card users.
Since July last year the official cash rate has been cut 1.25 percentage points, with mortgage rates down almost a full percentage point. But across a range of credit cards offered by the big four, the biggest cut has been a half percentage point on NAB's low-rate Visa.
Though the bank cut the rate, it pushed up the annual fee by $10, or 20 per cent.
Between July 2010 and July last year the official cash rate was pushed up a quarter percentage point. All the credit cards surveyed by Canstar on behalf of The Weekend West increased their rates by the same margin.
A record $37.1 billion is sitting on the nation's credit cards accruing interest.
Choice banking spokesman Matthew Levey said it was clear that banks, while responding to pressure on mortgage and business interest rates, were hitting their credit card customers.
"The issue is that if banks are cutting fees or rates in one place they're pushing them up somewhere else," he said.
But Australian Bankers Association chief executive Steven Munchenberg said the interest rates on credit cards were not linked to the official cash rate.
Rates on credit cards were also higher because they were an unsecured form of credit. "People should shop around to find a product that suits them," he said.
A spokesman for the Commonwealth Bank, which has some of the highest credit card interest rates, said cards were a riskier form of lending that attracted higher rates than other products.
A Westpac spokesman said rates on the bank's cards were reviewed regularly, irrespective of changes to the official cash rate.