Four in five people living on pandemic-boosted welfare payments will be forced to skip meals if the coronavirus supplement is cut.
Almost half of recipients will also have to ration their medicines, a new survey has found.
More than 2.2 million job seekers, young people and parents have received an extra $550 per fortnight throughout the coronavirus pandemic.
The Morrison government plans to slash the top-up payment by $300 in less than two weeks' time.
This will leave two in five people living on less than $14 a day after paying their rent.
More than half of survey respondents said the looming cut would make it much harder to pay rent and bills, and they would need to forgo some essentials.
The Australian Council of Social Services is using the findings to ramp up pressure on the government to keep the supplement in place.
ACOSS chief executive Cassandra Goldie called on the coalition to immediately extend the current income support beyond September and legislate a permanent boost to JobSeeker and other welfare payments.