TIN & CIF
Tax identification numbers (TIN)
Most EU countries use Tax Identification Numbers (TINs) to identify taxpayers and facilitate the administration of their national tax affairs. TINs are also useful for identifying taxpayers who invest in other EU countries and are more reliable than other identifiers such as name and address.
Financial institutions have to record the name and address of their account holders and, if there is one, the Tax Identification Number allocated by the EU country of residence for tax purposes. They must report the TIN, together with other personal and income details every year to the tax authorities of the country where they are established as part of their obligations under the Savings Directive.
TIN specifications (structure, syntax, etc.) are set by the national authorities. Some countries even have a different TIN structure for different categories of individuals (e.g. nationals and foreign residents).
For more information about TIN visit:
http://ec.europa.eu/taxation_customs/taxation/tax_cooperation/mutual_assistance/tin/index_en.htm