How to Do GSTR-3B Filing for Medical Shops — ITC Offset Guide

If GSTR-1 is your detailed outward diary, GSTR-3B is the summary return where tax is actually paid. For chemist shops, the entire game is table 4 — claiming the input tax credit on distributor purchases correctly, then paying only the balance in cash. Since 2024–25 the portal does much of the filling for you (from your GSTR-1 and GSTR-2B), so the real work is reconciling before you file.

GSTR-1 vs GSTR-3B in One Line

GSTR-1: invoice-level detail of outward supplies. GSTR-3B: summary of outward + inward supplies, ITC claimed, and the net tax paid. File both — consistently.

The Four Tables You Actually Fill

ITC: The Money You Claim Back

Every distributor invoice carries GST you paid — that is your input tax credit. Rules matter: ITC requires a valid tax invoice with your GSTIN, the goods must be used for business, and the supplier must have reported the invoice so that it appears in your GSTR-2B. Since October 2024 the portal's Invoice Management System (IMS) lets you accept, reject or keep pending each supplier invoice before GSTR-2B is generated — review it every month.

The Offset Order, Simplified

• Tax liability and ITC are tracked per head: IGST, CGST, SGST.
• Credit utilisation follows a prescribed cross-utilisation order (IGST first against everything, then cross between CGST/SGST within limits).
• Whatever credit cannot cover is paid in cash from the electronic cash ledger.

Your job is not to memorise the offset grid — it is to ensure the ITC figure going in is complete and reconciled. Software and your CA handle the arithmetic.

The Monthly Routine

1. Export the ITC register for the period (supplier-wise, rate-wise).
2. Review supplier invoices in IMS on the portal — accept, reject or keep pending.
3. Match the ITC register against GSTR-2B and chase suppliers whose invoices are missing.
4. Check the auto-filled outward figures against your GSTR-1 — they must agree.
5. File and pay by the 20th (monthly) or the 22nd/24th (quarterly QRMP, depending on your state).

Monthly GST Calendar for a Medical Shop

Dates can be extended by notification — always check the GST portal.

FAQ

• Can I claim ITC on expired stock? No. Section 17(5)(h) blocks ITC on goods written off or destroyed, so ITC already taken on expired stock you destroy must be reversed. Stock returned to the distributor against a credit note is a different case.
• What if a supplier has not filed? The invoice will not appear in your GSTR-2B and you cannot claim it yet — reconcile monthly rather than discovering it a year later.
• Do I file 3B every month? Monthly filers do. QRMP taxpayers file GSTR-3B quarterly and pay tax monthly through PMT-06.

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