Employers must file Form 5500 by the last day of the 7th month following the last day of the plan year. This means plans that began Jan 1, 2018 must file by July 31, 2019, or can request a 2 ½ -month extension by filing Form 5558 before the plan's original due date.
Governmental, church or Indian tribal plans aren’t required to file a Form 5500 since those plans are exempt from ERISA and its requirements.
Also, unfunded (means they pay benefits out of general assets and not a trust/plan assets), fully-insured, or combination unfunded and fully-insured health plans with less than 100 participants on the 1st day of the plan year are also excused from having to file the 5500. For example, if the plan has 99 participants as of Jan 1, 2018, the first day of their plan year, but went up to 105 participants on Jan 2, 2018, then they would NOT have to file Form 5500 as of July 31, 2019.
Remember, though, that the “plan” usually includes all of the component benefits together. In other words, if the employer-paid life plan had 100 or more participants on the 1st day of the plan year, but the medical plan only had 70, then if they are wrapped together into one big ERISA plan, then they must file Form 5500.
In addition, the plan administrator must give out the Summary Annual Report (SAR) within 9 months of the end of the plan year if they had to file 5500 in the first place. If a 5500 extension was filed, the employer must send the SAR within 2 months after the close of the period for which the extension was granted. For instance, a calendar year plan has to distribute the SAR for the 2018 plan year by Sept. 30, 2019. But if the plan applied for an extension to the Form 5500 filing, the SAR is then due within 2 months after the filing.
A totally unfunded self-insured plan, regardless of size, doesn’t have to provide a SAR.
Again, “unfunded” means they pay benefits out of general assets and not out of a trust. This is true even though large unfunded plans (with 100 or more participants) must file Form 5500. However, large fully-insured plans are subject to the requirement to give out the SAR.