Value-Added Tax (VAT) registration in Poland and the Czech Republic is required for participation in the Fulfilment Network Expansion (Central Europe Programme). When you start selling products that are fulfilled from Poland or the Czech Republic, the applied VAT depends on a number of different factors, for example, if the sale is local or cross border and if the sale has been made to a business or non-business customer.
There are also distance-selling thresholds, which apply to cross border sales to non-business customers.
Amazon provides a monthly Transaction Activity Report as a case log in Seller Central. The report contains information about sales, returns, refunds, and fulfilment-center movement across Europe. It is your obligation to review the data for accuracy before using it for any reporting or tax purposes.