All sellers are required to provide Amazon Business customers with a correct and valid VAT invoice for each order within one business day after the shipment of the order was confirmed. Similarly, credit notes on returns from Amazon Business customers must be provided within one business day of return confirmation. Amazon allows sellers to provide invoices and credit notes via the Amazon VAT Calculation Service, in which case invoices and credit notes are either generated by Amazon and automatically available for download in the customer account, or generated by the seller based on VAT calculation data provided by Amazon (via participating solution providers). In case sellers are not using the Amazon VAT Calculation Service, they can upload invoices and credit notes on Seller Central either manually via Manage Orders or automatically through their solution providers (preferred). If sellers are neither uploading their own invoices through Manage Orders nor using the VAT Calculation Service, they must send PDF invoices in an email to the customer email address, which is provided in the order reports.
Sellers not required to apply VAT on their sales still have to provide a receipt for each order from an Amazon Business customer.
For more information, please refer to this help page.