One of the architects of the Plutus Payroll tax scheme, Adam Cranston, and his lawyer co-conspirator, Dev Menon, both received lengthy jail sentences in August for their roles in the $105 million fraud.
Jurors sitting in on the nine-month trial also found Patrick Willmott, Jason Onley and Cranston's younger sister Lauren guilty over the plot.
All three have since been jailed.
The scheme involved siphoning money from legitimate clients through a series of second-tier companies from March 2014 until May 2017 when the funds should have gone to the tax office.
Adam Cranston, who is the son of former deputy commissioner of taxation Michael Cranston, joined with Menon and Onley in asking the NSW Supreme Court to let sheriffs investigate potential juror misconduct during the trial.
That bid was shut down by Justice Deborah Sweeney on Thursday.
The exact nature of the alleged misconduct is not known as it is subject to heavy suppression orders and the hearing for the application was held in closed court.
Justice Sweeney's written judgment will also be suppressed.
Adam Cranston was sentenced to 15 years behind bars, with a non-parole period of 10 years, after gaining more than $6.8 million through the scheme.
Menon was sentenced to 14 years with a non-parole period of nine years.
In total, 15 people have been jailed over the fraud, diverting funds that could have been spent on services such as health and education into the pockets of criminals.
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