GSTR-1 working builds itself from your invoices and notes. At month-end, clear the checklist and download the JSON.
Step by step
Open Returns → GSTR-1
Pick the month. Each table (B2B, B2C, CDNR, HSN summary) shows its documents and totals.
Clear the checklist
Fix what is flagged: missing GSTINs, HSN gaps, notes that need a reason.
Download the JSON
Click Export JSON. Upload it on the GST portal under GSTR-1 → Prepare offline, or send it to your CA.
Your CA can do this from their free seat, for all their clients.