I just learned about the new “XI” EU VAT prefix for Northern Ireland and I’ve been wondering — what do you do about GB customers? Do you contact all of them to find out which ones are in Northern Ireland and ask them to update their VAT numbers with you? Do you just ignore the problem (and risk trouble with your local tax office later)?
It seems that GB numbers can no longer be validated via the EU VIES system, so there is no way to verify if your B2B customer is indeed VAT-registered in the EU.