The document, a letter sent to KPMG on August 30, 2023, was tabled in redacted form earlier this month by the inquiry. It focuses on conduct by Philip Henry, who worked at the firm until his publicly reported departure in 2004.
The whistleblower alleges Mr Henry treated "female members of staff and clients inappropriately", including making "unwanted sexual advances". The letter also accuses him of receiving secret commissions paid in cash from a client after devising tax schemes, and in other instances receiving personal gifts from clients instead of fees or to reduce fees.
According to the letter, a redacted individual was "selling tax losses which Philip Henry knew to be non-existent or materially deficient and also knew that [redacted] had not filed income tax returns for more than 25 years".
The whistleblower states she was held responsible for wrongdoing she attributes to Mr Henry, including being pursued by tax authorities.
The inquiry is investigating how KPMG audit partners allegedly misused client data and mishandled a whistleblower's complaint about it. It has since heard from other whistleblowers at KPMG and other big four firms.
Separately, ABC News has reported on allegations against Chris Jordan, a former KPMG partner who later led the Australian Taxation Office. A 2021 whistleblower document alleged Mr Jordan avoided paying tax during his time at the firm and called his appointment to lead the ATO "corruption at the highest level".