Mr Shorten said Labor's tax package did not go far enough and voters had the impression the party was not "putting jobs first and foremost".

"We were doing tax reform but there was not enough in the way of tax cuts for people under $125,000," he said.

Labor had proposed tax refunds of up to $1080 for workers earning under $125,000, a figure matched by the Coalition. The Morrison government then offered greater tax cuts to higher income earners over the next decade. Labor offered slightly higher tax offsets to low and middle income earners.

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Mr Shorten, who is now the opposition's government services spokesman, ruled out a return to the Labor leadership. His intentions were first reported by the Herald Sun on Sunday.

"I've hung up my leadership running shoes," he said. "You don't have to be the leader to be a leader."

Shadow treasurer Jim Chalmers said Mr Shorten had "set an example for the rest of us" by taking responsibility for the loss.

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"We did have some big, controversial tax policies, and we did spread ourselves too thinly on the commitments that we made, that that growth story was obscured, and we got in our own way a little bit," he said on Sky News. "We can't afford to drag our bums around and mope around about the last election. We need to look to the future."

Dr Chalmers said Labor was still reviewing its policies but would not make an identical pitch to voters at the 2022 poll.