An Icelandic company carries two identifiers that are easy to confuse. One stays with it for life; the other exists only while it is registered for VAT. The difference matters on every invoice.
The kennitala
The kennitala is ten digits, written as six, a hyphen and four: 640707-0540. A company receives it on registration in fyrirtækjaskrá, and it survives a change of name, a change of owner and a change of address.
What surprises most people is that Iceland issues kennitölur to companies and to people from one series. A kennitala on its own therefore does not tell you which you are holding — except in one respect.
The forty that makes the difference
The first six digits are a date: day, month, year. For a company the day is the real day plus 40. A kennitala beginning 41 to 71 belongs to a company; one beginning 01 to 31 belongs to a person.
In the example above, 640707-0540, the 64 is really 24: the company was registered on 24 July 2007. That single rule is enough to classify a kennitala with no lookup at all, and it is why the check on this site can tell you whether a number belongs to a company without holding any register data.
The check digit
The ninth digit is a checksum over the other eight. Each position carries a weight — 3, 2, 7, 6, 5, 4, 3, 2 — the products are summed, the sum divided by eleven, and the remainder subtracted from eleven. A number that fails is a typo rather than a kennitala. The tenth digit is the century: 9 for the twentieth, 0 for the twenty-first.
The checksum refutes a wrong number without looking anything up. It does not establish that the kennitala was ever issued, to whom, or whether the company is still active. Only fyrirtækjaskrá knows that.
The VSK-númer
The VSK-númer is something else entirely. Only a company registered for VAT receives one, and it is five or six digits — not ten. In cross-border trade it is sometimes written with an IS prefix.
So every company has a kennitala; not every company has a VSK-númer. A company can also be removed from the VAT register without being struck off the company register — it keeps its kennitala and continues to exist, but may no longer charge VAT. The deregistration date is published in fyrirtækjaskrá, and it is the field to read when an invoice with VAT on it arrives from a party you do not know.
How to check which
The kennitala can be checked here: the checksum is computed in your browser and you are told immediately whether the number holds and whether it belongs to a company or a person. The VAT register is held by Skatturinn and is searched on skatturinn.is; Iceland is not in the EU, so no Icelandic VAT number appears in VIES.