Remove invoice_address_from_vat_id on save if it is not used

src/pretix/base/settings.py

@@ -4148,6 +4148,14 @@ def validate_event_settings(event, settings_dict):
                     )
                 ]}
             )
+    if (
+        settings_dict.get('invoice_address_from_vat_id') and
+        settings_dict.get('invoice_address_from_country') and
+        settings_dict.get('invoice_address_from_country') not in VAT_ID_COUNTRIES
+    ):
+        raise ValidationError({
+            'invoice_address_from_vat_id': _('VAT-ID is not supported for "{}".').format(settings_dict.get('invoice_address_from_country'))
+        })
 
     payment_term_last = settings_dict.get('payment_term_last')
     if payment_term_last and event.presale_end:

src/pretix/control/forms/event.py

@@ -63,7 +63,7 @@ from pretix.base.forms import (
 from pretix.base.models import Event, Organizer, TaxRule, Team
 from pretix.base.models.event import EventFooterLink, EventMetaValue, SubEvent
 from pretix.base.models.organizer import TeamQuerySet
-from pretix.base.models.tax import TAX_CODE_LISTS
+from pretix.base.models.tax import TAX_CODE_LISTS, VAT_ID_COUNTRIES
 from pretix.base.reldate import RelativeDateField, RelativeDateTimeField
 from pretix.base.services.placeholders import FormPlaceholderMixin
 from pretix.base.settings import (
@@ -531,6 +531,13 @@ class EventUpdateForm(I18nModelForm):
 
 class EventSettingsValidationMixin:
 
+    def clean_invoice_address_from_vat_id(self):
+        value = self.cleaned_data.get('invoice_address_from_vat_id')
+        country = self.cleaned_data.get('invoice_address_from_country')
+        if value and country and country not in VAT_ID_COUNTRIES:
+            return None
+        return value
+
     def clean(self):
         data = super().clean()
         settings_dict = self.obj.settings.freeze()