Guideline
If you enter an invoice for a customer from another EU country (Transactions > Sales > Create Invoices), the correct tax code is set automatically upon saving the transaction. This applies to items that are marked either as Goods or Services in the Item VAT Type of Nature field in the Item record ( Lists > Accounting > Items).
After you have selected a customer in the Primary Information section and an item on the Items tab, the tax code in the Tax code column defaults to the one on the Customer record – EC-DUMMY-FINLAND. This is a placeholder while the transaction is being entered.
When the transaction is saved, the tax codes defined in the Localization Settings record (Setup > Accounting > Localization Settings) is returned onto transaction line.