Chris Bowen will hit the ground running should Labor win the July 2 federal election.
The would-be treasurer would release the mid-year budget review within three months of being sworn-in rather than waiting until December, when the last three have been released.
He says it will provide an opportunity to reflect a Labor government's priorities, update forecasts to reflect a "realistic assessment" of key economic parameters and put a stamp on the economic agenda early in a Labor term.
Mr Bowen will tell the National Press Club in the traditional shadow treasurer budget-reply speech on Tuesday of his concerns for Australia's three triple-A credit ratings - a status only enjoyed by 10 countries.
He believes Treasurer Scott Morrison "doggedly insisting" that Australia doesn't have a revenue problem puts the rating at threat.
Losing one or all ratings would have real implications for the economy.
The cost of government borrowing would increase, states would have their ratings reviewed, as would major corporations and banks, increasing the cost of capital in the economy.
And once lost, a triple-A rating is very hard to get back.
Australia lost its AAA rating from Standard & Poor's in 1986 and it took 17 years to earn it back.
Mr Bowen believes the treasurer's plan to return to surplus is built on extremely "shaky foundations" and includes the biggest upward revision to the iron ore price in five years.
At $US55 per tonne - up from a previous forecast of $US39 - it is far more optimistic than some domestic and international banks.
"Hope is not a plan," Mr Bowen will say.
