Without researching, I will just say no. The notary serves the purpose of ensuring the signature is accurate and given freely. You are too involved and it makes it look like there is self dealing.
Promissory notes are not usually notarized in my experience. Try having him certify that he has read the promissory note and signs it under oath under the penalty of perjury under the laws of the state of Washington on _______ date in _____________, Washington. In Washington, that can act as the equivalent to a notary. It would add more gravitas to the Note. The statute is 9A.72.120 off the top of my head but I may be a little off. I am not in the office.
In every jurisdiction in which I have worked or needed documents notarized, a notary can not notarize a document in which they, their employer or a family member has any interest. The question then becomes what constitutes an interest. The quick way to find out would be to contact the Secretary of State.
I agree with the oother attorneys who have responded. You should not notarize the signature of any party on a contract to which you are a party or beneficiary.
The foregoing is general information based upon limited information, should not be construed as legal advice , and does not create an attorney-client relationship. The author is licensed in Indiana and Ohio attorney only.
(10) A notary public is disqualified from performing a notarial act when the notary is a signer of the document which is to be notarized.
The response does not constitute specific legal advice, which would require a full inquiry by the attorney into the complete background of the facts and circumstances surrounding this matter; rather, it is intended to be general legal information based on the limited information provided by the inquirer; it This response also does not constitute the establishment of an attorney-client relationship, which can only be established after a conflict of interest evaluation is completed, your case is accepted, and a fee agreement is signed.