A VAT number is used to identify a taxable person or non-taxable legal entity for VAT-related purposes. It is necessary for conducting economic transactions across borders within the EU and is required when supplying goods or services taxed with VAT, making intra-EU acquisitions, receiving services liable for VAT, or supplying services where the customer is liable for VAT. A VAT number is not the same as a Tax Identification Number (TIN), as TINs vary by country and are used for tax purposes.
Source Invopop
