Debate has reignited within the Federal Labor Party over the so-called "Buffett rule", which would impose a minimum tax rate on wealthy Australians.

Key points: Chris Bowen previously said Labor would not take the policy to the next election

Chris Bowen previously said Labor would not take the policy to the next election Giles, Butler says the Buffett rule is not the only way to ensure high income earner pay fair share of tax

Giles, Butler says the Buffett rule is not the only way to ensure high income earner pay fair share of tax Bill Shorten is detailing Labor plans to recoup revenue from large multinationals

Some in Labor have been pushing internally for the party to consider a mandatory 35 per cent tax rate on those earning more than $300,000.

Shadow treasurer Chris Bowen has previously shut down discussion on the topic, saying Labor would not take the policy to the next election.

But several ALP MPs are continuing to agitate for the Opposition to consider the issue.

On Wednesday, Labor frontbenchers Andrew Giles and Terri Butler reignited debate on the Buffett rule in an essay published by Australian Fabians.

"At a time when it is possible for Australian millionaires to claim so many tax concessions — including the cost of managing tax affairs — that they pay no income tax, the Buffett rule's appeal rests on an appreciation that today's tax settings are boosting inequality and unfairness, and that something should be done about it," the essay said.

The essay acknowledged the rule was not the only option when it came to ensuring high-income earners paid their fair share of tax.

"Nonetheless policy-makers should not underestimate its appeal to those who are concerned about inequality and unfairness," it said.

Shorten targets multinationals

It comes as Opposition Leader Bill Shorten further fleshed out Labor's plans to recoup revenue from large multinationals today.

Mr Shorten announced the Australian Tax Office would receive a $50 million funding boost per year to help it target multinational tax avoidance under a Labor government.

He said the move was expected to generate $200 million in revenue over four years.

Mr Shorten said Labor also planned to put a community sector representative on the Board of Taxation, to avoid its advice being skewed in favour of tax advisers and multinationals.

That comes on top of previously announced Labor policies to target multinationals.

That included amending thin capitalisation rules, lowering the threshold for the public reporting of private companies tax data from $200 million to $100 million, and removing the tax advantages multiple entity consolidated groups currently gain over Australian-owned ordinary consolidated groups.

"All told, Labor's new measures to make multinationals pay their fair share will deliver a budget improvement of $5.4 billion over the decade," Mr Shorten said.

"These are tax dollars legally owed to this country by wealthy corporations."