2. Review B2B invoices (with GSTIN) and B2C totals by state.
3. Open GSTR-3B for outward tax, input credit and net payable.
4. Fix anything the pre-filing checks flag (invalid GSTIN, missing HSN, wrong tax split), then download the GSTR-1 JSON and import it in the portal’s offline tool, or export Excel/PDF for your CA.
5. Under Tax → 2B Reconciliation, upload the GSTR-2B JSON from the portal to see which supplier invoices are matched, missing from your books or not yet filed before claiming input credit.
Tips
Make sure every customer with a GSTIN has it saved; otherwise the invoice lands in B2C.