International credit rating agencies are expected to maintain Australia's AAA status following the anticipated budget surplus that the federal government is set to present on May 8, likely pulling down banks and consumers borrowing costs for much of the current year.

RBC Capital Market analyst Su-Lin Ong has predicted Tuesday that more cash rate cutbacks will follow the policy move unleashed this week by the Reserve Bank of Australia (RBA), which reduced the country's benchmark borrowing cost from 4.25 per cent to 3.75.

Her readings, according to Ms Ong, point to the likelihood that government's net debt will peak at most below 10 per cent of the country's gross domestic product (GDP) level this year, directly in part to the spending cuts that the 2012-2013 Commonwealth budget carries.

As hinted by federal Treasurer Wayne Swan, the upcoming budget will mostly lay out "a substantial tightening of fiscal policy in the pipeline," Ms Ong said, which in turn will give more manoeuvring space for the RBA board to implement further rate reductions within the year.

"We expect the various ratings agencies to quickly reaffirm Australia's AAA, stable rating on budget night," the RBC strategist told the Australian Associated Press (AAP) on Tuesday in pointing out the clear economic benefits of the budget surplus that Prime Minister Julia Gillard has vowed to deliver.

"At face value, markets are likely to view the 2012/13 commonwealth budget in a reasonably positive light, especially against its global counterparts," she added.

The RBA has handed down on Tuesday its biggest reprieve in years to Australian borrowers by allowing the official interest rate to be slashed by 50 basis points after months of holding back.

Slow downs in global economic environment, particularly the expected cooling down of the Chinese economy, has been cited by the central bank as its primary reason in reversing its hold policy that remained in effect since December 2011.

It appears, however, that Australia's big four will not pass on to the banking public the full force of the cut, with National Australia Bank (NAB) announcing shortly after the RBA move that it will reduce its standard variable mortgage rate by only 32 basis points.

The Commonwealth Bank followed suit on Thursday, also deciding not to unveil the full swing of the cut by allowing only a slash of 40 basis points on its mortgage rates services.

The Australia & New Zealand Banking Group (ANZ) and Westpac have yet to indicate any hints that they will soon head south too on their respective loan rates, preferring instead to refer to their regular rates review this month as the likely prompt of their next move.

Mr Swan has been strongly pushing for the major banks to give their customers some breathing room by passing on the full cut, insisting that doing the otherwise will only serve as "an insult to hardworking Australians with a mortgage or small business, who will rightly feel short-changed."

These giant banks, he stressed, can very well afford to follow the RBA rates guidance for the month of May considering the fact that they have been raking in billions as profits each financial year, as proven by the $2.9 billion half-year profit reported on Wednesday by ANZ.

But Opposition leader Tony Abbott is pessimistic that the big ofur will take heed of the Mr Swan's appeal, stressing that the banks' contradicting actions on the official cash rate would merely highlight the reality that "yet again Wayne Swan has failed the basic test of competency in economic management."

His view was somewhat supported by Fortescue Metals Group (FMG) owner Andrew Forrest, who told a press on Wednesday that "there is an economic uncertainty in this country which is driven by a poor relationship which the government has with business because of its uncertain policies."

Mr Forrest could only hope that Australian banks would discern the immediate needs of the domestic economy - more boosts - and rolling out the full cut would indeed come as welcome respite for many business operators.