Ratings agency S&P Global has put Australia's triple A credit rating on negative outlook, saying there had been a "substantial deterioration" in the nation's finances and the country faced the risk of a deep recession.

As the Morrison government introduces its $130 billion JobKeeper program into the Federal Parliament, the agency said the fiscal and economic risks facing Australia were "tilted toward the downside".

On top of its JobKeeper program, the government has promised more than $66 billion in spending plus billions more in loan guarantees to help businesses survive pandemic-related closedowns.

Prime Minister Scott Morrison and Treasurer Josh Frydenberg arrive in the House of Representatives this morning to start debate on the government's JobKeeper wage subsidy. Credit: Alex Ellinghausen

S&P said Australia had strong institutions, credible monetary policy and a floating exchange rate which all helped support the country's triple A rating.