IF the custodian was to send withholding to IRS, but failed to do so, do not use Form 5329.
It you have a penalty on 1040 Line 38, you can ask the IRS to abate that due to
- custodian error.
- first time
See IRS website for more info.
@Laurelbeach
P.S. You were supposed to notice that immediately and send in the money yourself.