Auditors have warned that Australia’s AAA credit rating could be put at risk by the Federal Government’s failure to pass its policies.

Standard & Poor's says the deficit blowout in the Mid-Year Economic and Fiscal Outlook (MYEFO) this week was not enough to damage Australia’s rating, but it warns that the next six months may have “significant implications”.

The Government this week outlined its budget deficit blowout of $26.1 billion over four years from the seven months since its last budget.

S&P sovereign analyst Craig Michaels says the figures show the importance of the Government getting Senate approval for the large range of savings measures it has not yet pinned-down.

“The next six months could have significant implications for Australia’s budget outlook,” Mr Michaels said.

“Negotiations on tax reform appear to be drawing to a conclusion, and the Federal Government is due to release its first budget under its new leadership, which we expect would signal the current leadership's economic and fiscal policy priorities.”

But any future downgrade is still a fair way off, with all three major ratings agencies giving Australia a AAA score.

“The blowout in fiscal deficits is material, but doesn’t derail the budget outlook, and net debt is likely to peak at only a modestly higher level,” Mr Michaels added.

Fitch Ratings says the relatively low level of government debt gives Australia time to adjust before any future economic shock.

But Fitch warns that “a failure to rebalance the economy away from mining is a potential risk over the medium term which could put pressure on public finances and Australia's credit rating.”

The experts were keen to warn that Australia must keep control of its external vulnerabilities, which mean the nation’s government debt-to-GDP ratio must be lower than many of its AAA-rated peers.

The biggest vulnerabilities are Australia’s dependence on commodities and currently large account deficits.

“Fiscal projections for both economies are highly sensitive to macroeconomic assumptions, including global demand and commodity prices,” Fitch said.