It seems that with Voluntary Compliance Issues, it seems that at the top of the list are issues regarding plan compensation and conflict between practice and what the plan document says.
The issue exists when the plan sponsor administers a definition of compensation that is inconsistent with what the plan document says. That usually happens with bonuses where the intent is for the plan sponsor to exclude it and the plan document forgets to exclude it. That could be an issue as there is corrective contributions that may have to be made for missed deferral opportunities, as well as employer contributions.
It’s important that you check your practice in plan administration when it comes to the definition of compensation and whether it’s inconsistent with what the plan document says.