For the IRS penalty relief program, you should file the 2019 version of Form 5500-EZ. When submitting the delinquent return under the program, you must print in red letters in the top margin above the Form 5500-EZ’s title on the first page of the return: "Delinquent Return Submitted under Rev. Proc. 2015-32, Eligible for Penalty Relief." Additionally, each submission under the program must include a completed paper copy of Form 14704 attached to the front of the oldest delinquent return in the submission.
Sources:
Rev. Proc. 2021-30
Instructions for Form 5500-EZ (2019)
Instructions for Form 990-EZ (2023)
Instructions for Form 8950 (01/2022)
Instructions for Form 5300 (06/2023)
Instructions for Form 8955-SSA (2023)
Instructions for Form 5500-SF (2009)