Tom Seymour, who headed PwC from 2020 to 2023, will appear at a Senate inquiry into ethics and professional accountability on Friday.
The probe was launched after revelations emerged in January 2023 that PwC's partners had passed on confidential Treasury information to boost private sector business for the firm.
Five months after the news broke, Mr Seymour confirmed he had received emails relating to the information, apologised and stepped down.
He has maintained a low profile ever since, largely abandoning his LinkedIn and avoiding the eyes of the public.
But his 15 months of withdrawal will soon come to an end.
Mr Seymour is slated for a two-hour Senate grilling alongside his predecessor Luke Sayers.
Current PwC chief executive Kevin Burrowes will also appear alongside a host of other staff as he and his team continue to wrangle with the repercussions of the tax scandal.
The Big Four firm sold off its government consulting business for $1 to a private equity fund in June 2023.
In October, the former PwC partner at the heart of the affair, Peter-John Collins, was banned from providing financial services for eight years by the corporate watchdog.
A month later, the firm was fined nearly $100,000 after a disciplinary tribunal found it discredited the accounting profession.
And in March, the consulting giant announced would slash more than 300 jobs in an effort to "simplify" its business.
Former Telstra boss Ziggy Switkowski, who was appointed to lead an independent review into PwC's Australian operations, will also appear at the Senate inquiry.
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