When an extranormal person or someone from some kind of otherworldly origin (a spirit, a time traveler, a dimension-hopper, a robot, an immortal) is able to suddenly enter society and seamlessly pose as a normal human despite the major record gaps, lack of official citizenship, or other problems that would arise if it were to occur in real life. This usually involves someone from outside of the regular world who needs to slip into human society — space aliens in disguise and even aliens that don't need a disguise never seem to get the same problems with immigration that regular aliens have — but similar issues occur among immortals who have been alive for longer than modern citizenship records have existed and who seemingly don't need to reestablish a fake legal identity every few decades.

The character gets an Undead Tax Exemption. It's sometimes implied that they use mind control or magic to either brainwash or literally "magic up" an identity for themselves. It's usually used by evil characters/monsters/vampires because Villains Blend in Better while heroic ones will be a Fish Out of Water due to Rule of Drama. This isn't necessarily an issue in historical or fantasy settings, where it's not assumed that detailed censi and documentation exist and that it's usually possible to set up a new identity by just traveling far from your birthplace. In modern or science fiction settings, however, the growing importance of government ID, credit records, tax returns, job history, and other hard-to-forge proof of identity in order to do anything of note can make it difficult to explain how someone can just set up an entire identity and life off the books.

It is easiest for The Needless, since by definition they don't need the benefits of society. If one doesn't have to have money for food, clothing, or shelter, detection is not likely.

It can occur when the character is not extranormal but a sleeper government agent. Other mundane means to set up a fake ID usually involve getting a friendly (or bribable) hacker to set up a false identity, or impersonating someone else. A Monsters Anonymous group may have the resources to make one from scratch as well. A Conveniently Unverifiable Cover Story may be used to cover for any holes in the new identity.

Where this is a situation of an immortal or special who has to fashion the normal identity afterward, the reverse, where the normal person came first then had something happen, results in a Secret Identity and likely several Shouldn't We Be in School Right Now? moments.

Most of the time, this trope is dismissed with a handwave and covered by the Willing Suspension of Disbelief. If not, you may have a case of Surprisingly Realistic Outcome. The Doylist explanation for this trope is that watching someone fill out paperwork is boring in real life, so it would be just as boring in fiction; it's just assumed to have happened or isn't explained with the expectation that a viewer isn't supposed to ask that kind of question.

Historically this can be a justified trope. Prior to the twentieth-century, records tended to be sparse, difficult to retrieve, and even more difficult to verify. Without some overriding need justifying such efforts or a dissenting witness, identities and origins had to be taken at face value. If a character has been around for this time passing themself off as a descendant and then 'dying' and inheriting it several times see My Grandson, Myself. (Note this has its own logistical issues.)

See also Casual Car Giveaway, which is another situation where ordinarily expected paperwork is unnecessary. See Fantastic Legal Weirdness for other instances of speculative fiction elements having legal ramifications.

Examples: