July 31st, 2018
Form 5500, Annual Return/Report of Employee Benefit Plan is due to IRS for plans with 12/31 plan year-end. (Due seven months after plan year end.)
Form 5558, Application for Extension of Time to File Certain Employee Plan Returns is due for plans with 12/31 plan year-end. (Used for extension of Forms 5500 or 5300.)
Form 8955-SSA, Annual Registration Statement Identifying Separated Participants With Deferred Vested Benefits is due (without extension).