According to the new e-invoice directive, VAT code and VAT 0% phrase are required on all e-invoices that are entirely with 0 VAT or have rows with 0 VAT. Here you can find information about how to add it to your invoices and some examples if you're not sure which VAT code to use. 

You can add the VAT code and VAT 0% phrase while creating the invoice by 

1. clicking Show more details: 

2. and adding VAT code and VAT 0% phrase: 

If the VAT 0% phrase is always the same, then we recommend you to add it to the Invoice settings so you don't have to add it manually to every invoice. 

To do that go to Settings - Invoice Settings (scroll down a bit) - Default values and add VAT 0% phrase and VAT code: 

If, for example, your customer liable for the tax then the VAT code is AE - VAT reverse charge and VAT 0% phrase is Reverse charge. 

For invoices that have no 0 VAT, the VAT code S - Standard tax rate is added automatically. 

If you don't know which VAT code or VAT 0% phrase to use, please contact your accountant or the Tax Administration to get more information.