If Australia's major banks are accomplished in the art of 'mating calls' to coordinate aspects of their pricing, as some allege, National Australia Bank's top brass failed to engage in the ritual yesterday.Rather, the bank's CEO and CFO patiently explained to investors and the media, in separate briefings, the facts on margin trends and the pricing of liabilities as they apply to NAB.Mark Joiner, executive director of finance at NAB, told the investor briefing that "we've had about a 118 basis points increase in average cost of funds, 33 basis points of that coming since April, and, to date, we've recovered about 92 basis points.  "And so that leaves a gap of 26 as things stand today.  And there's nothing really that would suggest any of this is going to abate in any significant way going forward."Cameron Clyne, chief executive of NAB, was guarded when pressed by reporters for comments on the prospects of increasing margins on home loans."What we see the RBA saying is that the marginal cost of funds has stabilised," Clyne said. "But you have to add the change in deposit pricing and the cost of rolling over term debt. The RBA puts out one part of the story. There are other things to look at."On the other hand, NAB was more open, as most banks are, about seeking wider margins on business loans, although that particular trend may be coming to an end.Answering a question from an investment analyst in relation to the business bank, Mark Joiner said: "I think it's fair to say that we don't see any upside on margin.  We think margin has pretty much peaked."Joiner pointed out that NAB still had around 12 per cent of term funding to refinance, and reprice, at higher market rates."That will be the last repricing wave across the portfolio."Most of this will be completed over the next year.Joiner said NAB planned to issue between $25 billion and $30 billion in term debt over the new financial year, compared with a required refinancing task of around $22 billion.