A discrepancy in GST means any mismatch or inconsistency between the data reported in different GST returns, such as GSTR-1, GSTR-3B, and GSTR-2B. These mismatches trigger automated scrutiny notices from the GST department, and if unresolved, can lead to demand notices, ITC reversals, and penalties. As of 2026, the GST portal's AI-based matching engine flags discrepancies within days of filing.

• Over 70% of GST notices issued are due to ITC mismatch between GSTR-2B and GSTR-3B
• Discrepancies above ₹25 lakh are typically escalated for departmental audit
• Unresolved discrepancies can attract interest at 18% per annum plus penalties up to 100% of the tax amount

What is a Discrepancy in GST?

A discrepancy in GST refers to any difference, mismatch, or inconsistency found when the GST department cross-verifies data filed across multiple returns by a taxpayer or between a supplier's GSTR-1 and a recipient's GSTR-3B. The GST system is built on a self-matching mechanism, and when the numbers don't align, the system flags the taxpayer automatically.

Under the GST law in India (specifically under Sections 61, 73, and 74 of the CGST Act, 2017), the proper officer is empowered to scrutinize returns and issue notices when discrepancies are detected. These notices demand explanation, and if the taxpayer fails to respond satisfactorily, it can lead to demand and recovery proceedings.

Types of GST Discrepancies

There are several common types of discrepancies that GST authorities and the portal's automated system flag. Understanding each one helps you act quickly when a notice arrives.

GSTR-1 vs GSTR-3B Mismatch

This is the most common discrepancy. GSTR-1 captures outward supply details invoice-by-invoice, while GSTR-3B is the summary return used for tax payment. If the total taxable turnover or tax liability reported in GSTR-3B is lower than what GSTR-1 shows, it indicates possible underpayment of tax.

GSTR-2B vs GSTR-3B ITC Mismatch

GSTR-2B is the auto-drafted ITC statement generated from your suppliers' GSTR-1 filings. If you have claimed more Input Tax Credit (ITC) in GSTR-3B than what is reflected in your GSTR-2B, the portal flags this as an excess ITC claim. This is addressed through GST notices for ITC difference between GSTR-3B and GSTR-2B.

Supplier Non-Filing Discrepancy

When a supplier fails to file their GSTR-3B or GSTR-1, the ITC you claimed based on their invoice does not appear in your GSTR-2B. This creates a discrepancy where you have claimed ITC that is not verifiable from the supplier's end. Learn more about ITC notices when a supplier hasn't filed GSTR-3B.

HSN Code Mismatch

Under Rule 46 of the CGST Rules, invoices must carry the correct HSN (Harmonized System of Nomenclature) code. If the HSN code reported in GSTR-1 doesn't match the description or if there is an inconsistency across filings, the portal raises an HSN mismatch flag. See detailed guidance on HSN code mismatch in invoices and GST returns.

Ineligible ITC Claims

Section 17(5) of the CGST Act, 2017 blocks ITC on certain items such as motor vehicles (in some cases), personal expenses, food and beverages, and club memberships. If ITC is claimed on blocked items, the portal identifies it as an ineligible ITC discrepancy. Explore our guide on GST notices for ITC availed on ineligible items under Section 17(5).

Turnover Mismatch: GST vs Income Tax

The GST department also cross-verifies GST turnover with income tax return data. A significant gap between turnover declared in GSTR returns and what is reported in the income tax return (ITR) or books of accounts can trigger a scrutiny notice.

Common Causes of GST Discrepancies

Cause	Return Affected	Risk Level
Data entry errors in GSTR-1 or GSTR-3B	GSTR-1, GSTR-3B	Medium
ITC claimed before supplier uploads invoice	GSTR-3B vs GSTR-2B	High
Supplier defaults on filing	GSTR-2B	High
Wrong HSN codes used on invoices	GSTR-1	Medium
Claiming ITC on ineligible items (Section 17(5))	GSTR-3B	Very High
Amendments not captured in GSTR-1A	GSTR-1A	Medium
Time-of-supply errors (wrong tax period)	GSTR-1, GSTR-3B	Medium

Consequences of GST Discrepancies

Ignoring or improperly handling discrepancies can have serious financial and legal consequences for your business. Here is what can happen under the CGST Act, 2017:

• Scrutiny Notice under Section 61: The GST officer sends a notice (typically in Form ASMT-10) asking you to explain the discrepancy within 15 to 30 days.
• ITC Reversal: Excess or ineligible ITC is reversed, meaning you pay back the credit claimed along with 18% interest per annum from the date of availing the credit.
• Demand Notice under Section 73 (non-fraud): Tax demand raised with interest and a penalty of 10% of the tax or ₹10,000, whichever is higher.
• Demand Notice under Section 74 (fraud/suppression): Tax demand with interest and a penalty up to 100% of the tax amount due.
• GST Registration Cancellation: Persistent non-compliance or failure to respond to notices can lead to GST registration cancellation.

How to Identify GST Discrepancies?

You should proactively reconcile your GST data before the department flags it. Here are the key reconciliation steps every GST-registered business must follow in 2026:

1. GSTR-1 vs GSTR-3B Reconciliation: Compare your outward supply details and tax liability across both returns every month.
2. GSTR-2B Matching: Before claiming ITC in GSTR-3B, verify each ITC entry against your auto-populated GSTR-2B. Claim only what appears in GSTR-2B unless you have valid reasons under Rule 36(4).
3. Supplier Follow-up: If a supplier's invoice is not appearing in GSTR-2B, follow up with the supplier to file their GSTR-1 promptly.
4. Books vs Returns Reconciliation: Periodically reconcile your purchase and sales registers against GST return data to catch timing differences.
5. Annual Reconciliation in GSTR-9C: For businesses with turnover above ₹5 crore, GSTR-9C (reconciliation statement) is mandatory and captures all major differences between audited accounts and GST returns.

How to Resolve GST Discrepancies?

Once you receive a scrutiny notice or identify a discrepancy internally, resolution must be approached step by step. Here's a practical approach as followed under Indian GST law:

Step 1: Analyse the Notice

Read the notice carefully (typically Form ASMT-10 or DRC-01). Identify the exact return, period, and line item where the discrepancy has been flagged. Check the demand amount and the deadline to respond.

Step 2: Gather Supporting Documents

Compile invoices, purchase registers, supplier communication, bank statements, and any ITC ledger records that can support your position or explain the mismatch.

Step 3: File a Reply or Amend the Return

If the discrepancy is due to a genuine error, you can amend GSTR-1 using GSTR-1A (available for current period corrections). For GSTR-3B errors, adjustments may be made in subsequent returns. File your reply on the GST portal within the notice deadline.

Step 4: Pay the Demand (If Applicable)

If the tax demand is valid, pay the tax, interest, and applicable penalty through the electronic cash ledger. This stops further escalation and interest from accruing further.

Step 5: Seek Expert Help for Complex Cases

For discrepancies involving large amounts, multiple periods, or fraud allegations, always involve a GST professional. A poorly drafted reply can escalate the matter. Taxocity's GST filing and compliance team handles end-to-end notice responses and reconciliation with a 100% compliance guarantee.

You can also check our detailed guide on how to respond to a scrutiny notice for GST return discrepancies.

GST Discrepancy vs GST Error: What's the Difference?

Aspect	GST Discrepancy	GST Error
Definition	Mismatch between two or more returns or datasets	Incorrect data entry in a single return
Detection	Automatic by GST portal matching engine	Manual review or internal audit
Resolution	Reconciliation, reply to notice, or ITC reversal	Amendment in subsequent return or GSTR-1A
Legal Consequence	Can lead to demand notices and penalties	Usually correctable without penalty if caught early

How Taxocity Helps with GST Discrepancies

Taxocity has been helping Indian businesses with GST compliance for over three decades. Our team of real human GST experts handles everything from monthly GST filing and GSTR-2B reconciliation to drafting replies for complex discrepancy notices. We offer end-to-end support from registration to scaling, backed by a 100% compliance guarantee and a 4.8/5 rating from 5,000+ satisfied clients.

Whether you've received an ASMT-10 scrutiny notice, a DRC-01 demand notice, or simply want to proactively prevent discrepancies through monthly reconciliation, our experts are available to assist you right away.

Key Takeaways

1. A GST discrepancy is any mismatch between data in GSTR-1, GSTR-3B, or GSTR-2B detected by the GST portal's automated matching system.
2. The most common discrepancies involve ITC mismatch between GSTR-2B and GSTR-3B, and outward supply differences between GSTR-1 and GSTR-3B.
3. Unresolved discrepancies attract 18% interest per annum plus penalties of 10% to 100% of the tax demand.
4. Monthly reconciliation of GSTR-1, GSTR-3B, and GSTR-2B is the best way to prevent discrepancy notices.
5. For discrepancies involving large amounts or fraud allegations, always consult a GST professional before responding.
6. As of 2026, GST notices are increasingly driven by AI-based analytics, making proactive compliance more important than ever.

Frequently Asked Questions

What happens if a GST discrepancy is not resolved?

If a GST discrepancy is not resolved within the notice period, the GST officer can pass an assessment order raising a tax demand under Section 73 or 74 of the CGST Act. This demand includes the unpaid tax, 18% annual interest, and a penalty ranging from 10% to 100% of the tax amount depending on intent.

Can a GST discrepancy lead to registration cancellation?

Yes. Persistent failure to respond to discrepancy notices or continued non-compliance can lead to suspension and eventual cancellation of your GST registration under Section 29 of the CGST Act.

How long do you have to respond to a GST discrepancy notice?

Under Section 61 of the CGST Act, a taxpayer must respond to a scrutiny notice (Form ASMT-10) within 15 days of receipt. The officer may grant an extension on written request, but it is critical to respond before the deadline to avoid ex-parte assessment orders.

Is every ITC mismatch a discrepancy in GST?

Not always. Minor timing differences where a supplier files their GSTR-1 late but eventually does file can result in temporary ITC mismatches that self-correct. However, if the mismatch persists or exceeds prescribed limits, it is treated as a discrepancy requiring formal reconciliation or reversal.

---

Disclaimer: This article is for informational purposes only and does not constitute tax advice. GST laws are subject to change, and the applicability of specific provisions may vary based on individual facts and circumstances. Please consult a qualified tax advisor or GST professional before making any decisions based on this content.