“[T]he DOL has been known to send notices to plan sponsors who have filed a 5500 for their large retirement plan but have not filed a 5500 for their health and welfare plan…. [C]ompanies with large retirement plan are also likely to cover enough people for their welfare plan to have a filing requirement, although the correlation is not certain because how participants are counted is different for retirement plans and welfare plans.” See full article at Belfint Lyons Shuman