Q: How should the middle name and name suffix fields be completed?
A: For item 6 - Middle name: Enter the individual's middle name or middle initial. Leave this item blank if the middle name or middle initial is unknown or does not apply. Do not record also known as (AKA) or doing business as (DBA) names in Item 6. Record these names instead in Item 8 “Alternate name.”
For Item 6 - Name suffix: Enter the individual’s name suffix such as JR, SR, III, etc. if it is part of the individual’s legal name. Leave this item blank if the suffix is unknown or does not apply.
This is addressed in the "FinCEN Currency Transaction Report Electronic Filing Requirements" guide, Attachment C.