pii.national_id_se
A Swedish personnummer or samordningsnummer, 10- or 12-digit form — valid Luhn checksum and a plausible date — appears in the free text.
What it looks at#
Two shapes, both checked the same way. The 10-digit form is a YYMMDD date (optionally
followed by - or +) plus a 4-digit suffix. The 12-digit form — the common shape in
Swedish systems today — spells out the full four-digit year instead: YYYYMMDD,
optionally followed by -, plus the same 4-digit suffix. Either way, the last 10 digits
(century digits excluded) must pass the Luhn checksum used for both personnummer and
samordningsnummer. Samordningsnummer (numbers issued to people without a Swedish
personnummer, e.g. some temporary residents) use the same shape with the day of birth
offset by +60 — a day of 61-91 is treated as exactly as valid as 01-31.
Why it matters#
The personnummer is Sweden’s single national identifier, used across healthcare, banking, government services and employment. It’s high severity because knowing it, combined with a name, is often enough on its own for identity fraud in Swedish institutions.
What to do#
High severity. Redact before storing or forwarding; this is squarely the kind of identifier this gate exists to catch.