The former Newcastle Knights forward's legal representatives sent a letter to the NRL last week, according to News Corp Australia.
The lawsuit is also reported to include Melbourne Storm's Jordan McLean, who was handed a seven-game NRL ban for his involvement in a three-man spear tackle that left McKinnon with a spinal injury.
It is understood McLean is being personally sued by McKinnon over the March 2014 incident at AAMI Park.
But an NRL spokesperson told AAP the league believes no claim has been lodged, and have been in contact with McKinnon's lawyer.
The 24-year-old McKinnon's rugby league career was cut short by the tackle that has left him in a wheelchair.
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He expressed a desire to sue last year despite receiving the maximum $500,000 compensation payout from the NRL and around $1.2 million for his medical costs through fundraising efforts.
But McKinnon, whose legal team has reportedly met with NRL boss Todd Greenberg, has said that will be nowhere near enough in the long-term.
"I had no idea how much this injury was going to cost," he told the Nine Network in July 2015.
"I didn't know until two weeks ago it cost $100,000 for me to get out of bed in the morning.
"I just need to know how much it is going to cost me, how much money I have and where I (am) going to get that money from."
NRL club Melbourne have declined to comment.
