Data commissioned by the Australian Council Of Social Service (ACOSS) suggested two-thirds of households on incomes of up to $100,000 would be worse off under the plan.

The federal government could double revenue to $130 billion in 2017-18 if it increased the GST to 15 per cent and dramatically broadened the tax base, according to new figures from the Parliamentary Budget Office (PBO).

Analysis by the National Centre for Social and Economic Modelling (NATSEM) commissioned by ACOSS showed the current 10 per cent GST consumed 13.4 per cent of disposable income for those in the bottom fifth of households, but that would rise to more than 20 per cent if the rate was lifted to 15 per cent.

Households in the top 20 per cent would experience a much milder impact, increasing from 5.9 per cent of disposable income to 8.8 per cent.

Broadening the base to include fresh food, water, sewerage, health and education would hit the poorest hardest, the research showed, with the 13.4 per cent of disposable income jumping to nearly 18 per cent compared to a rise for the wealthiest from 5.9 per cent to 7.6 per cent.

Treasurer Scott Morrison said the idea to increase the GST to 15 per cent was not official policy and was at the "extreme end" of options available as the government considered its tax reform package ahead of the next federal election.

ACOSS did not dismiss a GST hike, but wanted the focus of the tax debate to be on stamp duties and business taxes.

"Fairness and simplicity would be undermined and it would do little or nothing to improve economic efficiency," ACOSS chief Cassandra Goldie said.

Three former Labor premiers, Kristina Keneally (NSW), Peter Beattie (Queensland) and Geoff Gallop (WA) say they would support an increase in GST subject to conditions including compensation for low-income earners, federation reform and extra money for health and education.