He has reportedly been accused of placing small bets on opposition players.
NRL chief executive Todd Greenberg has maintained the game must take a strong stance on betting violations and match fixing.
Channel Nine revealed that the NRL has asked Simona for details on the relationship between himself and the charity, and wants some transperancy on the trail of funds.
"The spotlight will be turned onto Tim Simona's relationship with at least one charity.
"Simona has been auctioning off items, such as jumpers and boots, with a view to raising money, but he is now being grilled by the NRL for his activities and, more specifically, about where the money raised from the items is going."
It's understood the NRL has grave concerns whether all the money has made its way to the charity. Nine has sought comment from each charity, but those attempts were not returned.
It's believed the latest details will further strengthen the NRL's case against Simona and he is expected to receive an 'indefinite' ban from the game.
Meanwhile, the Rugby Football League has closed the door on any possible chance of Simona salvaging his career in England.
There has been speculation Simona may be allowed to play in the Super League, where Todd Carney was handed a life-line after he was sacked by Cronulla in 2014, following his infamous bubbler incident and deregistered by the NRL.
However, an RFL official said no team would be permitted to sign a player serving a NRL ban and Simona's case is very different to that of Carney.
"Todd was never actually banned by the NRL," a RFL source told AAP. "He was deregistered and they [the NRL] just wanted him out, but there was no actual ban put in place to prevent him playing.
"But if a player is suspended or banned by the NRL, that would carry on into Super League."
That news would also scupper any potential chance of Ben Barba avoiding his 12-match suspension should his move to French rugby with Toulon fail to work out and he targets a return to league.
Barba, who tested positive for cocaine in the wake of Cronulla's grand final celebrations last year, jetted out for France last month, where his suspension was overlooked to allow him to play in the Top 14 competition.
"It's a hypothetical situation, as he is playing rugby, but he wouldn't be able to sign for any Super League team while he was under a ban," the source said.