Chelsea could be deducted points by the Premier League due to transfers that happened many years ago.
The twin deals that took Willian and Samuel Eto'o from Anzhi Makhachkala in August 2013 are under investigation.
Willian, who now plays for Fulham in the Premier League, was signed for £30 million.
Eto'o, who played for Barcelona and Inter Milan in his heyday, was signed on a free transfer deal.
Per The Times, the club has self-reported alleged secret payments from the previous regime.
Neither player is thought to have any knowledge of the payments, as they were uncovered by the Todd Boehly-Clearlake Capital consortium.