One of my client is selling goods in UK and around European Countries since 2014. The sales are made through UK VAT registered company. All the VAT due on European sales made to non vat registered clients has been duly accounted for and paid to HMRC. However, due to changes in regulation in Germany they asked my client to register for VAT as they were selling goods above certain threshold. This was done in October 2019. But now they received email from German tax authorities that they are liable for VAT since 2014.
Can some one please help to clarify if this can be true and if yes how to make adjustments on UK VAT return for the VAT alreay paid?