1. The business partner must be entered in the address book, with their VAT number filled in and the "VAT payer" checkbox selected.
2. In the invoice, select the posting rule that carries the VAT fulfillment code: supply of goods or services.
If both of these conditions are met, Flexi will automatically set VAT lines 005-008 T or 005-008 S, and the invoice will be reflected in the recapitulative statement. A prerequisite here is, of course, that the given business partner has one of the EU member states listed.