Notaries may have a client who wants an incomplete document notarized, which is why it is important for a notary to understand which blank spaces are acceptable and which documents to turn away.
Documents with unfilled fields
In many states notarizing an incomplete document is illegal and should never be done. Even if it not illegal in your state, leaving a blank space in the document can lead to dishonest business practices and potential lawsuits.
Blank signature spaces
Sometimes you may be asked to notarize a document when all the signers are not present. This is generally allowed, so long as the other signers will sign the document in the presence of another notary later. You can notarize the signers who are with you but make sure to note the unfilled spaces in your journal.
Blank government spaces
In a few cases the government will need to complete a document and a space sectioned off the paper with headers like "For Official Use Only". In this situation you may notarize the document even if the section is blank. Again, note the unfilled section in your journal just in case.
As always, it is wise to review your state's policy on this matter and to always follow its regulations.
Have you been asked to sign blank documents in the past? What did you do?