Providing a VAT number is not mandatory when registering in LUCID; the taxpayer reference number is sufficient. The primary purpose of the VAT number is to regulate cross-border transactions within the EU for value-added tax reasons. In many countries, as in Germany, this number is different from a regular identification or taxpayer reference number. Anyone without a VAT number will be automatically prompted to enter a taxpayer reference number after indicating accordingly. Companies/businesses generally are assigned a taxpayer reference number that they are required to include in their tax returns and invoices. Small businesses receive a commercial taxpayer reference number that differs from the owner's private taxpayer reference number, once the tax authority has received notification of their business.