Have a few questions on this if anyone knows from their own experience. How does one obtain this UPIN and would it help prevent denials/delays due to identity mixups? So far I haven't been delayed or denied, but thinking this might help avoid some issues I've seen other users have to deal with. I have zero criminal record, save for a trespass citation for being on a beach after hours when I was just out of high school (and the beach's sign was very badly covered by a bush, should have fought that crap but oh well). Also, do most people here put their SSN on the 4473? Is there a noticeable difference in delay/deny when doing this?