The federal Labor opposition must defend the mining tax and aim to engage with small business, leadership candidate Bill Shorten says.
He believes the 30 per cent minerals resource rent tax on the super profits of coal and iron ore mining companies, which the coalition government plans to scrap, "was the right idea".
"I believe we need to advocate for the retention of the mining tax," Mr Shorten told a Per Capita forum in Melbourne on Wednesday.
At the same time he attacked the government's plan to reinstate a 15 per cent tax on the superannuation contributions of people who earn less than $37,000.
"Who on earth dreamt up this proposition the coalition's got that ... you put a new 15 per cent tax on 3.5 million workers and take a tax off the richest multinationals in the world," he said.
"It's not right."
Mr Shorten also said his party must engage with small business, which has legitimate concerns over red tape when it comes to tax laws and the implementation of GST.
"I think there are opportunities for us to examine our tax system, but what we also need to recognise is the best way to grow government revenue is to stimulate economic growth," he said.
He said revenue is a challenge for all governments in terms of revenue.
But he noted that if in the five years of the Labor government it had had the revenue revenue of the previous five years of the Howard government "we would be in surplus".