Can I use a notarized passport copy as a supporting document?
No, unfortunately. A notarized copy is one that a public notary bears witness to sighting and provides a seal/signature to confirm legitimacy. The IRS does not accept notarized documents anymore and in fact hasn’t since 2011. If you send notarised documents you are application will be delayed and rejected eventually.
You will need to provide either a certified document or the original copy. A certified copy is one that the original issuing agency provides and certifies as an exact copy of the original document and contains an official stamped seal from the Agency.
Alternatively, you can also use a Certifying Acceptance Agent (CAA) like ITIN Genie to avoid having to submit your documents to the IRS or get certified copies made by an embassy or issuing agency.