Icelandic identification number

ID numbers are composed of ten digits. For a personal ID number, the first six of these are the individual's date of birth in the format DDMMYY.[1] The seventh and eighth digits are randomly chosen when the ID number is allocated, ranging from 20 to 99 (with some exceptions). The ninth is a check digit, and the tenth indicates the century of the individual's birth: '9' for 1900–1999, '0' for 2000–2099. ID numbers are often written with a hyphen following the first six digits, e.g. 120174-3399.
D₁D₂M₁M₂Y₁Y₂R₁R₂PC
D = day, M = Month, Y = year, R = random, P = parity, C = century.

The check digit equation is:

${\displaystyle P_{0}=(3D_{1}+2D_{2}+7M_{1}+6M_{2}+5Y_{1}+4Y_{2}+3R_{1}+2R_{2}){\bmod {1}}1}$

${\displaystyle P={\begin{cases}0&{\text{if }}P_{0}=0\\11-P_{0}&{\text{otherwise }}\end{cases}}}$

The consequence of this design is that at most 80 people can be born on the same day. The exact same formula is used for the identification numbers of organisations and companies, instead of the date of birth the initial registration date is used and then the number 4 is added to the first digit to makes sure there are no conflicts with individuals.

The system is similar to that employed by some other European countries, but Iceland makes unusually extensive and public use of its ID numbers, with businesses, educational and medical institutions eschewing internal identification numbers in favour of the national system, and its use being mandated in banking transactions. In most cases, instead of a business issuing a customer or account number, the ID number is used. Even the flag-carrier airline Icelandair uses the national ID numbering system for frequent flier numbers.

Furthermore, online banking services in Iceland offer a lookup service to check names against numbers. Because of their public nature, ID numbers are not used for authentication. The completeness of the National Register has eliminated the need for the country to conduct a regular census: population statistics can be obtained by simply querying the database.

The introduction of electronic IDs (eIDs) has reinforced the extensive use of the ID number in everyday life. Institutions and companies alike use the eID, tied to an ID number, to login and authenticate users, by use of a mobile app. For example, the process of logging into the healthcare portal is the same as logging into a subscription TV account, as they are tied to the same ID number.

The Icelandic ID number is displayed on all official identity documents: Icelandic identity cards, Icelandic passports and Icelandic driving licences, as well as most official documents, bills and registrations.

One issue is that having an ID number is usually a prerequisite to accessing most government services, banking services and even some businesses transactions. This can be a hinderance to newly settled residents, as it takes some time to apply and be issued a new ID number.

• National identification numbering in Iceland
• Icelandic identity card
• Icelandic passport
• Icelandic driving licence

• Watson, Ian (2010). "A short history of national identification numbering in Iceland". Bifröst Journal of Social Science. 4: 51–89. doi:10.12742/bjss.2010.3.