Slovenia introduced the Unique Master Citizen Number on January 8, 1977 and applied to all citizens born before then and alive at the time. The Unique Master Citizen Number is a standard identification number, assigned by the Ministry of the Interior.

The Unique Master Citizen Number consist of 13 digits as follows:

DDMMYYYRRSSSX

DD - day of birth

MM - month of birth

YYY - year of birth, last three digits

RR - a constant value 50

SSS- serial number combination of sex and serial number for persons born on the same day (000-499 for men and 500-999 for women)

X - checksum of first 12