A bulky balaclava might seem like a great idea for freezing days, but it's not a good match for helmeted skiing. Thick construction and raised seams can create uncomfortable pressure points under your helmet pads, especially on your forehead. More importantly, excess bulk can change how your helmet sits on your head, which compromises its safety performance in a crash.
Bulky balaclavas are really designed for non-helmet use—think lift operations, extreme cold conditions where you're prioritizing maximum warmth over helmet integration, or casual resort days when you're not wearing a helmet at all. If you try to force one under a snug-fitting helmet, you'll likely be adjusting it all day and dealing with headaches.
If you always ski with a helmet (as most riders should), look for an "optimized helmet fit" balaclava instead. These use flat seams and low-profile fabrics that seal in warmth without the bulk, keeping you both warm and properly protected.