Ahead of today's expected cut in Australia's official interest rate, the Australian Bankers' Association has launched a pre-emptive strike against critics.In a media release yesterday, ABA chief executive Steven Münchenberg argued that the Reserve Bank of Australia would not necessarily expect banks to follow its rate cut. And he gave a detailed breakdown of how rates of all types have moved in the past 12 months."The Reserve Bank understands the cash rate is just one component of the true cost of banks' funding and therefore does not expect banks and other lenders to exactly match every cash rate movement," he said."The Reserve Bank Board takes into account what borrowers are actually paying in the marketplace for loans and what they are receiving on deposits when making their decision."Münchenberg's statement comes at the end of a tough 12 months in the public debate about bank interest rates.For some time, the ABA has been seeking to break the connection in the public's mind between RBA rate cuts and bank rates.A year ago this week, the ANZ became the fist major bank to embrace this strategy. It declared it would announce changes for retail and small business variable interest rates on the second Friday of each month - and not in reaction to every RBA rate change.So far this strategy has not obviously succeeded in taking all the heat out of the rate debate. Instead, the past year has seen accusations that the banks are trying to take monetary policy control out of the RBA's hands. (The RBA has rejected these accusations.)The ABA has now responded by setting out in more detail the better deals banks have been forced to offer depositors."Banks are facing higher funding costs mainly due to the competitive rates being paid on deposits," Münchenberg said in his statement."Prior to the GFC, term deposits were priced on average 200 basis points below the cash rate. Now, they are 20 basis points above the cash rate.""While interest rates on deposits remain attractive and competitive for savers, when combined with the cost of wholesale funding, deposits continue to put pressure on the overall cost of funds for banks."The ABA received some support for its stance from an unexpected quarter yesterday: the centre-left think tank Per Capita issued a report saying banks "are rightly the arbiters of their own rate settings, and rising funding costs have indeed led banks to raise rates." However the report, which is entitled "What Price Stability?", also argues that "the Big Four banks are more profitable than the risk attached to their equity would justify." It advocates the creation of a new government-owned bank to offer "lower-cost, no-frills banking services".