This error indicates that the selected VAT code requires an additional fields (and mandatory) in the booking screen; goods or services and VAT NR.
In this case, there are no ICP / ICV VAT code setup in the company settings in Basecone. And therefore the additional fields will not appear in the booking screen, however the ICP / ICV VAT code can still be selected for booking and the error above will appear when you try to book the invoice.
Company settings in Basecone
In Basecone, go to Settings - Company - Action (edit) - tab Settings and go to section VAT settings. Select the ICP / ICV VAT code in the correct field (sales or purchase) and scroll down to save the settings.
After the VAT code is saved, go to the booking screen and select that same VAT code. The additional fields will appear as follows:
Choose the a performance type: goods or service
Fill in the country code and the VAT number
When all fields are entered, you can now book the invoice.
Still getting an error?
If you are still getting an error and similar to the image below, this means that VAT settings is not correctly set up in Twinfield. Go to Settings - Company settings. Control both VAT and VAT group settings.
Go to the settings of the VAT code and control which VAT group is selected in the allocation rules;
Go to the selected VAT group and control if the option is selected for ICT (Intra-Community Transactions).