September
15th: Required contributions are due for pension plans (Money Purchase, Target Benefit, and Defined Benefit plans) that end on the calendar year. 2017 profit sharing or matching contributions for calendar fiscal years for plan sponsors who filed a corporate tax extension are also due.
30th: Summary Annual Report (SAR) due to participants or beneficiaries receiving benefits under the plan as of the 12/31/2017 plan year end. The SAR is due on 9/30 (nine months after the plan year end) for calendar year plans that have not extended the due date of Form 5500.
October
1st: For 401(k) plans that will elect to utilize safe harbor provisions for 2019, the safe harbor notice must be provided to participants between October 1st and December 1st.
15th: Deadline for filing Form 5500 for those calendar year end plans on extension. Deadline for filing Form 8955-SSA for those calendar year end plans on extension.