John Farnham's manager Glenn Wheatley has pleaded guilty to three tax-related charges.
The 59-year-old admitted not declaring his $256,000 income from Farnham's Talk of the Town Tour.
The court heard Wheatley paid it into a Swiss-based tax minimisation scheme that is now under investigation as part of the Australian Crime Commission's Operation Wickenby.
Wheatley has also pleaded guilty to avoiding his tax obligations as promoter of a 2003 Kostya Tszyu boxing match.
Wheatley told the court he was deeply ashamed of his actions.
He added he was angry he has become the public face of Operation Wickenby because of a leak, despite promises from authorities that his case would be kept confidential until today.