Notarizing an incomplete document exposes a signer to fraud, so no official instrument should be notarized unless it is complete and free of blank spaces.
Incomplete documents have great potential for fraudulent misuse. A borrower, for example, might sign an incomplete promissory note trusting the lender to fill it out, and then later find that the lender wrote in twice the amount actually borrowed, or an increased interest rate. In these cases, the document signer could be severely damaged, and the Notary may be required to testify in a subsequent lawsuit.
The prudent Notary will ask a signer to fill in any blank spaces, or have the signer take the document back to the issuing agency for completion, before notarization. If the spaces are inapplicable and intended to be left blank, the signer should be asked to line through each space or write “NA” in the blank space.