Treasurer Wayne Swan is set to unveil today a more-detailed economic forecast showing the Budget remains on track to return to surplus even with the revamped resources tax by 2013.

The Federal Government will use today's release of revised projected revenue to prop up its economic credentials as Prime Minister Julia Gillard prepares to call an election.

The Opposition, however, thinks the update is a smokescreen, designed to hide large losses of earnings given away in talks over the resources tax.

The Gillard Government has been forced by the Opposition to provide figures supporting its claim that $10.5 billion will be collected over four years.

Mr Swan says the latest data will prove the budget will go back to surplus in three years. He also says he is happy to unveil more details about the forecast revenue from the remodelled resources tax.

"There's been a degree of uncertainty in the global economy, there is a community appetite for more detail," he said.

"What I will be able to confirm is that the budget will be surplus in three years, three years early ahead of every major advanced economy.

"That's quite an achievement for Australia."

Opposition's Treasury spokesman Joe Hockey, however, expects to hear more falsehoods from the Government about the resources tax.

"Treasury weren't even in the building for the negotiations and yet they're claiming now they're going to have miraculously $10.5 billion in the budget in the forward estimates based on assumptions that one can only assume are absolutely heroic," he said.

Access Economics forecaster Chris Richardson says today's prediction should not vary much from what was in the budget.

"The broad global recovery is proceeding, China is still doing very well there are no big differences there," he said.

"The same for the Australian economy. Retail is slow, the pace at which the recovery in housing construction is arriving is also slow, even there however, it's not that different ... the same basic economic picture for Australia that we had at budget time."