We have had many issues sending in the electronic VAT returns as they are sent without validation.

I found out that the period year and period number are mandatory fields. My idea is that these fields are validated correctly before sending the message so that the user get a chance to actually correct this before submitting. If other countries also use electronic VAT returns, move the validation forward to the UX as the technical validation result from Skatteetaten/ID porten is useless.