A lot of kirana and grocery shop owners hand-write invoices that look fine but are missing something the GST rules actually require — usually harmless for a cash customer, but a real problem if a business customer later tries to claim input tax credit on it and it gets rejected.
What a valid GST invoice must show
- Your GSTIN and the buyer's GSTIN, if they're registered.
- A sequential invoice number — not reused, not skipped; GST rules require a continuous series for the financial year.
- HSN code per item — required once your turnover crosses the threshold that mandates it, and good practice even before that.
- Tax breakdown, not just a total — CGST and SGST (or IGST for interstate) shown separately per item or per rate slab, not bundled into one number.
- Place of supply — matters for whether it's CGST+SGST or IGST.
The mistake that causes the most rejected claims
The single most common issue: showing one combined "tax" line instead of splitting CGST/SGST (or showing IGST when it should have been CGST+SGST for an intra-state sale). A business buyer's accountant will kick this back, and by then you're re-issuing invoices instead of running your shop.
Doing this by hand vs. software
None of the above is hard individually — the problem is doing it correctly, per item, on every single bill, during a busy counter hour, without a mistake. That's exactly the repetitive-but-strict task billing software exists for: it fills in GSTIN, generates the sequential number, splits the tax by slab, and prints a format your customer's accountant won't reject.
MyHisaab generates a correctly formatted GST invoice — GSTIN, HSN, CGST/SGST or IGST split, sequential numbering, UPI QR — for every sale, automatically, and it's free during early access. As with any billing tool, confirm anything specific to your registration status or edge cases with your CA.