Australian Greens Senator Bob Brown expressed his support on the federal government's proposal of a one-off levy that will fund a big chunk of its rehabilitation program for a large swathe of areas hit hard by the flooding disaster.

However, Senator Brown wants to ensure that the flood levy would be configured based on taxpayers' income and those with average pay slip should be written from any tax obligations.

The Greens leader stressed that "it would be better if low-income earners were exempted since we're a wealthy country," adding too that every taxpayer must be counted for the levy, most especially the business sector.

The proposed flood levy, according to the federal government, is a viable option for source of financing the recovery plans after the flooding even as Prime Minister Julia Gillard issued assurance that her office will release its official policy on the matter very soon.

That policy should answer concerns on whether the levy, which has been scored by the Coalition as an additional burden for Australians still reeling from the damages left behind by the flooding, would be implemented at all and when.

Ms Gillard said that imposing the levy is a difficult decision for her to make in light of the recent developments but he also stressed that in order to get the job done, sacrifices need to enter the picture.

She pointed out that "Australians I think understand that part of the contract between us, part of the thing about being Australians together is that we work together in tough times."

Federal Treasurer Wayne Swan has scheduled later this week the release of his initial assessment on the economic damages wrought by the flooding, leaving hints that the numbers could prove daunting and the flood levy may solve most of the problems created by the disaster.

Swan said that the proposed levy is a common sense answer for what he called as dramatic costs that entail the government's recovery program.

Still, the Coalition appears far from convinced of the levy's necessity as opposition treasury spokesman called on Ms Gillard that perhaps scrapping the national broadband network project could free up needed resources and allow the government to roll out reconstructions minus the benefit of a levy.