Amazon gives you two Merchant Tax Reports a month and collects TCS on every sale, but it does not
The Merchant Tax Report (MTR) B2B and B2C files in Seller Central under Reports and Tax Document Library are the source for GSTR-1; each row is an invoice line, a refund line or a
MTR B2B rows with a customer GSTIN go to Table 4, B2C rows go to Table 7 (or Table 5 for large inter-state invoices), and all TCS supplies are restated operator-wise in Table 14.
Refund rows in the MTR are credit notes Amazon issued in your name; they belong in Table 9B or net off in Table 7, never as deleted invoices.
Amazon's 0.5 percent TCS is accepted in the TDS and TCS credit received tab and then pays part of your GSTR-3B liability from the electronic cash ledger.
Go to Reports, then Tax Document Library, then the Merchant Tax Report section.
The full guide has the formats, the deadlines and the worked examples.