Every month end, amazon will generate a GST Invoice to the Seller. This invoice will have the commission charges, Shipping charges, marketplace fees, (around 4-6 heads). This invoice is usually sent to the registered email of the Amazon Seller. Alternatively the Amazon seller can download the same from his seller login under Reports -> Tax document Library -> Seller Fee Invoices.
Please also note that the Amazon seller needs to deduct TDS on the above invoices and deposit the same. Once he submits the Form 16A is submitted to Amazon, they will reimburse the same