Manchester City and Paris St-Germain are facing fines in the region of €60m (£50m), restrictions on their Champions League squad size and a wage limit for failing Uefa financial fair play rules.
BBC Sport has learned the two – among nine clubs under examination by Uefa for failing the governing body's "break even" test – face similar penalties.
It is believed a Champions League squad reduction could see the clubs restricted to using anywhere between 18 and 21 players in Uefa's premier competition.
A normal squad size is 25.
A wage cap could also be introduced on the errant clubs to ensure there is no rise on this season's squad wage bill for the Champions League.
It is thought clubs have until Friday to agree a "settlement" with Uefa.
Failure to agree a deal would see a club referred to an adjudicatory panel in June where a non-negotiable penalty would be applied.
At that stage clubs could then seek a final appeal at the Court of Arbitration for Sport in Switzerland.
Under Uefa's FFP rules, clubs can lose no more than £37m (€45m) over the previous two seasons.