Welcome aboard! The Form I-9 does NOT require a notarial act , therefore you must NOT affix your notarial seal impression on it. You are signing the form in the capacity of an Authorized Representative of the verifying employer, so it is recommended that you indicate “Authorized Representative” as your title, not “Notary Public.” It is an Employment Eligibility form, and you are merely verifying the persons identity, and that the same person was given and filled out the form. Basically, anyone the employer designates as the authorized representative can do this, it doesn’t have to be a notary. I think it just makes them feel more comfortable/secure having a notary do it being they can’t do it themselves. On a more important note, check you state laws (SOS) to verify your even permitted to do I-9 assignments. Additionally, for your benefit (and my 2 cents), because it is not a “notarial act” it SHOULD NOT be recorded in your notary journal, but I HIGHLY recommend you record it somewhere (like on a spreadsheet or something). Hope this helps!