If you know it’s just one employee you can send as soon as you discover the error. If you don’t know who may have been missed (including dependents added after original enrollment) you can send everyone the letter at the start of a new plan year.
Sienna Faulkner Thank you. That was my feeling to just send the notice to all participants at the beginning of the plan year as I believe from my audit it is multiple EE's. I have been at my current company for 4 weeks and I am reviewing current practices and policies right now.