GST update — CBIC circulars of 26 October 2026: Circular No. 258/2026 requires show-cause notices to set out the facts and calculations and limits the use of Sections 74/74A to cases with evidence of intent to evade; CBIC Instruction No. 02/2026 (30 October 2026) also states that no show-cause notice is to be issued for demands below ₹10,000. GSTR-1 and GSTR-3B due dates are unchanged.
Quick answer: Most GST return errors come down to a handful of repeat mistakes: mismatched invoice data, missed input tax credit reversals, wrong tax head payments, and late filings. Catching these before you file saves you notices, penalties, and hours of correction work later.
1. GSTR-1 and GSTR-3B Mismatch
Your outward supply figures in GSTR-1 need to match what you report in GSTR-3B. When they don’t, the mismatch shows up in the department’s automated reconciliation and often triggers a notice. Double-check both returns against your sales register before submitting.
2. Claiming Input Tax Credit Without Matching GSTR-2B
ITC claims that don’t match your GSTR-2B (auto-generated from your suppliers’ filings) are a common trigger for scrutiny. If a supplier hasn’t filed on time, their invoice won’t reflect in your 2B, and claiming that credit anyway can get flagged or reversed later with interest.
3. Wrong Tax Head Payments
Paying under the wrong head, CGST instead of SGST, or IGST instead of CGST/SGST for an intra-state supply, is a frequent and entirely avoidable error. The amount paid doesn’t automatically shift heads, so this usually means paying twice: once to correct it, and once to recover the wrongly paid amount through a refund process.
4. Missing Reverse Charge Mechanism (RCM) Liability
Certain purchases, like from unregistered dealers or specific notified services, require you to pay GST yourself under RCM. This is easy to miss, especially for smaller purchases, but the liability doesn’t go away just because it wasn’t reported.
5. Late Filing and the Interest It Triggers
Even a few days’ delay on GSTR-3B attracts interest on the tax liability, plus a late fee per day. For businesses filing multiple GST registrations across states, missing even one deadline adds up fast.
6. Not Reconciling Books with GST Returns Periodically
Waiting until year-end to reconcile your books against what’s actually been filed is where most errors compound. A monthly or quarterly check catches mismatches while they’re still easy to fix, rather than during the annual return when corrections get complicated.
How to Avoid These Mistakes
- Reconcile GSTR-1, GSTR-3B, and your books every filing cycle, not just at year-end
- Check GSTR-2B before claiming any input tax credit
- Set internal deadlines a few days ahead of the actual due date to leave room for corrections
- Keep a checklist for RCM-applicable purchases
- Get a professional review before filing if your transaction volume is high
A simple monthly routine
- Close the month’s sales and purchase registers.
- Match purchases with GSTR-2B and the Invoice Management System; follow up with suppliers who have not filed.
- Check reverse-charge purchases and blocked credits.
- Prepare GSTR-1 and GSTR-3B from the same data and compare the figures before filing.
- Pay under the correct tax head and keep the challan and return acknowledgements.
Related: see our full guide on GST services.