Retroactive plan termination amendment

[John A]

Can a 401(k) profit sharing plan be terminated retroactively? If so, are there any limitations on when termination amendment must be adopted (such as by 2 1/2 months after end of plan year)?

[PensionPro]

IRM says, The proposed termination date may not be retroactive except when it will not reduce any participant's accrued benefit. So it sounds like esp with a PSP you could have a retroactive plan term date. Any thoughts?

[K2retire]

How do you retroactively notify employees that they won't be able to defer? Isn't that notice required 30-60 prospectively?

[PensionPro]

I see the original post referenced a 401(k) PSP but I am dealing with a standalone PSP as well as a non-PBGC DB plan.