Nothing to say on Medicare levy hike: PM

Prime Minister Malcolm Turnbull and his finance minister won't say whether the government is considering a modest increase in the Medicare levy.

Senior government figures from the prime minister down are using the "we-don't-talk-about-hypotheticals" defence to avoid questions on hiking the Medicare levy.

Independent senator Nick Xenophon believes a small increase in the taxpayer levy for those earning more than $90,000 would go a long way to plugging an unfunded gap in the cost of the national disability insurance scheme.

"I am not going to get into a debate about hypotheticals," Malcolm Turnbull told Sky News when asked whether the government was open to a modest increase.