Prime Minister Malcolm Turnbull has acknowledged an increase in the Medicare levy will be an extra tax on families, but says it's worthwhile because it will help fund the national disability insurance scheme.
"Are you going to turn around and say in a few years' time to parents of disabled kids, 'Sorry, there's no money in the till'?" he told ABC radio.
"Now it is fully funded so you'll know if you have a disabled child ... you will know the money is there, and it's there because Scott Morrison included it in the budget last night."
Mr Turnbull said the Senate had not backed the government's savings measures to allow it to fund the NDIS otherwise.
The government looked at the half per cent already in the Medicare levy to help fund the NDIS and decided to add another half point - lifting the levy to 2.5 per cent total from July 2019.
"For many Australian families, they will feel it ... but there's a benefit," he told Sky News.
"This is just, fair, responsible."
Crossbench senator Nick Xenophon said his team would look at the measure "favourably".
"We want the NDIS to be successful and to work and to deliver the enormous potential it can for the people with disabilities," he told ABC TV.
Opposition Leader Bill Shorten said he believed the government could find other ways to fund the the NDIS.
"We're not sure the case is made just to automatically increase the taxes for everyday Australians," he told Seven on Wednesday.
"If the government is looking for some extra money, they don't need to give a tax cut to millionaires on 1 July and I don't need to go ahead with corporate tax cuts."
Labor has not ruled out supporting the increase, although Opposition Leader Bill Shorten said he was not convinced it was the only way for the government to fund the NDIS.
"We're not sure the case is made just to automatically increase the taxes for everyday Australians," he told Seven on Wednesday.
"If the government is looking for some extra money, they don't need to give a tax cut to millionaires on 1 July and I don't need to go ahead with corporate tax cuts."
Shadow treasurer Chris Bowen said the opposition would take time to respond to the proposed increase.
"It would be irresponsible to rule out supporting it," he told ABC radio on Wednesday.
