pii.national_id_nl
A Dutch BSN (burgerservicenummer) appears near a recognisable label like "BSN" in the free text.
What it looks at#
An 8- or 9-digit number (8-digit numbers are zero-padded to 9 before testing, as the
Dutch tax authority’s own spec does) that passes the “11-proef” weighted checksum,
and the word BSN or burgerservicenummer within about 40 characters of it. The
11-proef alone is weak — a random 9-digit number passes it about one time in 11 — which is
why D-78 requires the nearby label as well.
Why it matters#
The BSN is the Netherlands’ national identifier, used across healthcare, tax, benefits and government services.
What to do#
High severity when it fires. Because this check requires a label nearby, a bare BSN-shaped number with no such label present will not be caught — a known gap, not a false negative in the usual sense.