Prime Minister Julia Gillard has denied allegations the Federal Budget is dishonest because it includes $12 billion in earnings forecast to come from the controversial RSPT.

"I think we need to take a little bit of a breath and settle down on words like dishonest," she told the Macquarie Network today, when questioned about the Budget's forward estimates.

The Budget was the Government's forecast for revenue and expenditure, the new prime minister said.

"We don't sit here with a magic pile of cash."

According to Ms Gillard, growth forecasts were supported by sound Treasury advice.

"On the projections for the economy we obviously rely on Treasury advice and forecasting," she said.

"And that is the way governments have done their budgets since Adam was a boy."

The Budget's forward estimates allow for revenue from the RSPT, which the Government intends to impose on miners beginning 2012.

Meanwhile, Ken Henry will keep his role as federal Treasury secretary under the new government, with Ms Gillard defending his performance.

Although Dr Henry's review of taxation had brought forth the debatable RSPT, his work had to be put into perspective, the new prime minister said.

Dr Henry was one of the people who had ensured Australia remain buoyant during the financial crisis, she said.

When questioned about the truthfulness of the Treasury chief's advice on tax reform, Ms Gillard answered: "In weighing that up, you should also be weighing up the advice he gave us and the work he did with (the) Government as we responded to the global financial crisis."