GST returns: GSTR-1 and GSTR-3B, section by section

01 Generate a return

GST is filed per GSTIN. Outlets that share a GSTIN produce one combined return.

Go to Compliance → GST returns.
Choose 1 · Outlet (GSTIN), 2 · Return (GSTR-1 or GSTR-3B) and 3 · Period (the month).
Choose Generate.The return opens on its own page. Generating again later rebuilds the draft from your latest records.

One tab per section, in the columns your CA's GST software uses.

The figures at the top: taxable value, tax, Non-GST (petrol, diesel) and nil-rated.
B2B lists invoices to customers with a GSTIN, invoice by invoice.Add a credit customer's GSTIN in Credit → Customers and their purchases move here.
B2C (others) is all other counter sales by state and rate, net of their credit notes.
Exempt, Nil, Non-GST carries petrol and diesel as non-GST supplies — the law asks for them in Table 8.
Cr notes list voided sales to registered buyers; voids of ordinary counter sales are netted into B2C (others), as the portal expects.
HSN — registered / unregistered summarise by HSN code, unit and rate; Documents lists the invoice and credit-note series used.
Read any warning at the top — for example a product without an HSN code — fix it, then choose Regenerate.

The monthly summary and the tax you pay.

3.1 shows outward taxable supplies, nil-rated, reverse-charge inward and, in (e), petrol and diesel as non-GST.
3.2 lists inter-state sales to unregistered buyers by state.
4 ITC is the credit from counter-stock purchases and expenses — IGST where the supplier is in another state.
5 carries the oil company's fuel invoices as non-GST inward supplies.
Tax payable shows each head after credit; a negative figure is credit carried forward.

Reverse charge, ITC reversals, reclaimed or ineligible credit, interest and late fee come from your books.

On a draft GSTR-3B, scroll to Adjustments.
Enter the figures — for example transport (GTA) bills under reverse charge in 3.1(d) and the matching credit in 4(A)(3) — and a note for your CA.
Choose Save and rebuild.The return is rebuilt with them, and they stay with it.

Give your CA the Excel, or upload the JSON yourself.

Choose Excel (GST offline tool) on GSTR-1.The latest GST offline-tool template (b2b,sez,de, b2cl, b2cs, cdnr, cdnur, exp, at, atadj, exemp, hsn(b2b), hsn(b2c), docs), plus a GSTR1 Report sheet listing every invoice and credit note, and an itemSummary sheet product by product.
Choose Portal JSON to upload the return on the GST portal.
After filing on the portal, choose Mark filed.OCTYN does not submit anything to GSTN; Mark filed records what you did, and the return can no longer change.

Done. Both returns built from your own records, checked section by section, and ready to file. Open it in OCTYN.