Crown non-executive director Nigel Morrison on Tuesday said he first learned the company may have avoided paying the tax through media coverage of a royal commission on June 7.

"I was shocked by the magnitude," Mr Morrison told the inquiry into whether Crown can retain a licence for its Melbourne operations.

"The magnitude was unbelievable."

The inquiry previously heard Crown minimised the amount of gaming tax it had to pay by deducting marketing costs, including free valet parking, from its pokies revenue.

This practice, which spans back to 2012, may have saved Crown Melbourne as much as $272 million in avoided tax.

Other estimates have come in at $167 million and $200 million, while Crown's chief financial officer Alan McGregor says the figure stands at about $8 million.

But Mr Morrison, who joined Crown as a director in March, said the issue of potential tax avoidance demonstrated a cultural problem at the company.

"It tells you they had an attitude that, if they didn't think it was overly important and that they could get away with it, they did," he told the inquiry.

The inquiry was told Crown sought legal advice about the tax issue in 2018 as it thought the Victorian Commission for Gambling and Liquor Regulation was "digging around".

Mr Morrison, who previously served as a Crown Melbourne executive from 1993 to 2000, said the company "clearly" lacked an "open and honest" relationship with the gaming regulator.

Mr Morrison also revealed he had been left with an "impression" the company may have been underpaying tax following a 30-second chat with Crown head Xavier Walsh in March.

Commissioner Ray Finkelstein asked Mr Morrison if he was concerned that Crown's executive chair, Helen Coonan, had known about this since February without disclosing it to him.

He said yes.

Commissioner Finkelstein, a former Federal Court judge, later asked Mr Morrison whether, hypothetically, directors should resign if they knew their company was underpaying tax but took no steps to fix it.

"In that case ... it's hard to argue they should remain," the Crown board member said.

Mark Mackay, Crown's executive general manager of gaming machines, previously said Crown adopted the deductions practice to make its loyalty program cheaper to run.

But he also said the company was concerned about the VCGLR finding out.

The royal commission was set up by Daniel Andrews' Labor government after a NSW inquiry found Crown unsuitable to operate its newly built casino in Sydney's Barangaroo.

Crown employees are set to give evidence in a closed hearing on Wednesday.

The inquiry's public hearings are expected to continue on Thursday with evidence from Crown's security and surveillance head Craig Walsh.

Australian Associated Press