The IRS doesn’t give any specific guidance in the 2021 Instructions for Form 3520 for reporting excess gifts on line 54.
However, you’d be fine if you’d enter “SEE STATEMENT ATTACHED” in the description for the third entry on line 54.
Then, attach a brief letter of explanation and an actual statement of any excess gifts, providing the information required in columns (a), (b) and (c) that weren’t included on line 54.
