Unique Master Citizen Number (Serbo-Croatian: Jedinstveni matični broj građana / Јединствени матични број грађана, JMBG / ЈМБГ, Macedonian: Единствен матичен број на граѓанинот, ЕМБГ, Slovene: Enotna matična številka občana, EMŠO) is an identification number that was assigned to every citizen of former Yugoslav republics of the SFR Yugoslavia.
The JMBG was introduced in the Socialist Federal Republic of Yugoslavia on January 8, 1977[1] and applied to all citizens born before then and alive at the time.
When the law to that effect was passed in 2003[5] it was no longer possible to use JMBG on identity cards, driver's licenses and similar documents.
Seeing flaw of hiding MBG, on January 1, 2009 Croatia passed a new law[6] that introduced a different unique identifier called the Personal Identification Number (Croatian: Osobni identifikacijski broj, OIB).
[8] The number is made up of 13 digits in a form "DD MM YYY RR BBB K" (whitespaces are for convenience; digits are written without separation) where: The checksum is calculated from the mapping DDMMYYYRRBBBK = abcdefghijklm, using the formula: Note: there has been a small number of JMBGs that were assigned by valid authorities but which had an invalid checksum.