Prime Minister Malcolm Turnbull has been tripped up on Australia’s median income, as his government suffered a major setback on tax cuts aimed at high-income earners.

Asked in Parliament on Wednesday afternoon to quote the median wage, Mr Turnbull said he would have to take the question on notice.

“But it is certainly well below the average full-time weekly earnings, because many Australians are working part-time and are therefore on low earnings,” he replied.

“Rather than make an attempt to pick a number, I will take that on notice and I will come back to the honourable member on it.”

Labor seized on the moment to argue the Prime Minister was out of touch with working people.

“Malcolm Turnbull is as clueless about the median income of Australian workers as he is about Australian workers in general,” newly-appointed Labor president Wayne Swan wrote on Twitter.

At the end of question time, Mr Turnbull clarified the median wage was $53,000.

Throughout question time, Labor had accused the government of attempting to help the wealthy at the expense of the lower-paid through its tax cut plan unveiled in the budget.

“Can this arrogant and out-of-touch Prime Minister confirm that, under his tax scheme, a telco executive from Sydney’s upper North Shore, earning $1 million a year, gets a tax cut of over $7000, but a shop assistant in western Sydney, selling phone plans, gets a tax cut of just $10 a week?” Labor’s Michelle Rowland asked at one point.

“Is this why the Prime Minister is telling working Australians who are doing it tough to just get a better job?”

Mr Turnbull and other frontbenchers hit back, saying aspiration was a “mystery” to Labor, and that it had forsaken the policies Paul Keating and Bob Hawke had aimed at the upper middle class.

As The New Daily reported recently, there are various ways of estimating the median wage. It can be as high as $55,063 or as low as $44,527, depending on the measure.

Earlier in the day, the third part of the government’s tax plan, aimed at people earning up to $200,000 a year, was voted down in the Senate.

Labor and the Greens teamed up to tie an upper house vote, effectively stripping out the third and final stage of the cuts due to start in 2024.

Late on Wednesday afternoon, the government was successful in a motion imposing a 6.30pm limit on Senate debate on the tax cuts.

That will force a vote in the Senate and mean the bill can be sent back to the lower house sooner. Once there, the government has the numbers to pass the complete package again.