Does the customer mean that you want to invoice him for VAT? It is illegal to issue sales invoices with the seller's own VAT number. In which country is your VAT number registered? If it is in Europe, according to the EU Remote Sales Law, every EU country has a certain amount of tax exemption. If it exceeds this amount, you must apply for the VAT number of the destination country. If it does not exceed the amount, you can issue a VAT invoice in your own VAT country.