The Australian Council of Social Services say governments should look at taxing land rather than goods and services.
Land tax has been the missing piece from the debate over a proposed GST hike, says a key social welfare body.
NSW Premier Mike Baird on Monday stepped up his campaign for the the GST to be lifted to 15 per cent.
But Australian Council of Social Services chief executive Cassandra Goldie said the move would be unfair on Australia's lowest income earners.
She welcomed tax reform debate but not at the expense of Australia's lowest paid workers.
"Land tax is the most economically efficient type of tax in Australia," she said.
"It's the big piece missing from the tax debate."
Dr Goldie said only high income earners would be winners under the Baird proposal, which would use the funds raised by the increased GST to reduce personal income tax.
"We don't think it's the right thing to do, we don't think it's fair and it's not good for the economy," she said.