Australian taxpayers have to work nearly one-and-a-half weeks full-time every year just to pay for subsidies and tax concessions for the fossil fuel, superannuation and private health insurance industries, according to the Australian Greens.

That figure is based on the same formula used by Treasurer Joe Hockey last week when he warned taxpayers had to work over four weeks every year ''just to pay for the welfare of another Australian''.

Mr Hockey used his calculation to explain to the right-leaning Sydney Institute last week why Australia's welfare system was unsustainable.

''This year the Australian government will spend on average over $6000 on welfare for every man, woman and child in the country,'' Mr Hockey said.