The VAT number is one of the most important parts of every transaction. It serves to specify the tax treatment of certain transactions and to enable the tax authorities to monitor the application of the new regulation. This pretty much explains why a company's and customer's VAT number must be included on invoices for tax-exempt supplies and other goods and services within the European Union. The sales tax identification number is therefore a part of the control procedure that replaced the previous border controls (EC sales list).
As SAP Silver Partner, we have full access to the "European Union VAT Checking" functionality offered by SAP Business One. Thus, we can check the validity of a customer's VAT number on the official website of VIES with just one click.