SSN

SE (Swedish Personal Number personnummer)

Accepts the value in the following formats:

• YYYYMMDDXXXX
• YYMMDDXXXX

In case of 10 digit format, it adjusts the ‘year’ to a four-digit year based on the assumption that two-digit years greater than the current year are in the past century (1900s), while two-digit years less than or equal to the current year are in the current or upcoming century (2000s).

Reference: https://www.skatteverket.se/privat/folkbokforing/personnummer.4.3810a01c150939e893f18c29.html