A manufacturer we work with discovered that a single wrong HSN code, used consistently across two years of invoices, had resulted in his buyers being unable to claim ITC correctly — and an ASMT-10 scrutiny notice in his direction.
From FY 2026-27, all businesses with turnover above ₹5 crore must report 6-digit HSN codes on every invoice and in every GST return. For manufacturers, HSN errors are particularly expensive — they affect your own ITC claims on inputs and your buyers’ ITC claims on your output, in both directions.
Not sure whether your HSN codes are correct under the new structure? WhatsApp us and we’ll audit your HSN mapping.
Quick Summary — HSN Code Requirements
| Turnover | Minimum HSN Digits Required |
| Up to ₹5 crore | 4 digits on B2B invoices (B2C can be exempt in some cases) |
| Above ₹5 crore | 6 digits mandatory on all invoices and in all returns |
| E-invoice filers | 6 digits mandatory regardless of turnover (since e-invoicing threshold is ₹5 crore) |
| GSTR-9 HSN summary | Matches invoice-level requirements |
💡 TaxKitab Tip The most dangerous HSN error isn’t using a completely wrong code — it’s using a code that’s almost right. A manufacturer who uses a 4-digit HSN correctly but guesses the last two digits of the 6-digit code typically generates invoices that look plausible but attract a different GST rate than what actually applies. The buyer claims ITC on a rate that may not match what was actually charged. Six months later, both sides have a mismatch they can’t explain. Get every HSN code verified against the tariff schedule, not estimated. — From our GST Manufacturers Guide (Book 5). Available at taxkitab.com/books
💡 TaxKitab Tip Don’t rely on your supplier’s HSN code. Two businesses selling similar-looking products may legally classify them under different tariff headings depending on the product’s composition, intended use, or manufacturing process. Always classify your own products independently using the latest CBIC tariff schedule. One incorrect HSN code can affect GST rates, your buyer’s ITC, annual reconciliation, and even trigger departmental scrutiny.
Why the GST 2.0 Rate Change Made HSN Accuracy More Critical
Before September 2025, the 12% slab acted as a buffer for some classification uncertainty — getting a product into approximately the right category was often enough. With the 12% slab gone, many products now sit exactly at a boundary between 5% and 18%. A wrong HSN code no longer just affects your classification — it may now determine whether you’re at 5% or 18%, a difference of 13 percentage points on every invoice. Getting the 6-digit code right is now a rate determination question, not just a reporting formality.
The Most Common HSN Errors in Manufacturing
Using a generic/parent HSN code instead of the specific sub-heading. The 4-digit code covers a broad category. The 6-digit code specifies the actual product within that category. These often carry different GST rates. Assuming the 4-digit and 6-digit codes attract the same rate is the most common and costly error.
Using the same HSN code for different product variants. A manufacturer making two similar products in different materials — plastic vs metal, for example — may correctly use the same HSN for both physically, or may need different cod Using the same HSN code for different product variants. A manufacturer making two similar products in different materials — plastic vs metal, for example — may correctly use the same HSN for both physically, or may need different codes depending on the specific tariff entry. Don’t assume physical similarity means the same HSN.
Not updating HSN codes after GST 2.0 reclassifications. Several goods were reclassified in the September 2025 rate change. If a product’s GST rate changed, its HSN may have also been reclassified. An HSN that was correct before September 2025 may now be incorrect under the new rate notifications.
Using the input HSN on the output invoice. A manufacturer buys raw material under one HSN and sells finished goods under a different HSN. The input HSN determines your ITC eligibility on purchase; the output HSN determines your output GST rate on sale. Using the wrong one on either side creates mismatches in both directions.
What Happens When an HSN Error Is in Your Filed GSTR-1
An incorrect HSN in a filed GSTR-1 flows into your buyer’s IMS dashboard tagged with that HSN. If the wrong HSN carries a different rate, the ITC your buyer receives may not match what you actually charged. Amendment through GSTR-1A can correct HSN errors in filed GSTR-1 — but only for current and immediately prior periods. Older errors need separate assessment.
How to Fix This Before It Becomes a Notice
Start with your product master list in your billing software. Map every product code to a 6-digit HSN using the CBIC tariff search tool at cbic.gov.in — not a third-party site, and not the pre-September 2025 version of the schedule. For any product where you’re uncertain, get a formal opinion before using a code across thousands of invoices. For products already invoiced with a potentially wrong HSN, check whether the rate difference is material and whether GSTR-1A amendments are still available for those periods.
Frequently Asked Questions
Is there a penalty specifically for using the wrong HSN code?
Section 125 covers general penalty for any failure not covered by a specific provision — up to ₹25,000. Beyond that, if the wrong HSN results in an incorrect GST rate being charged, the demand and penalty provisions under Section 74A apply to the tax shortfall for FY 2024-25 onward.
How do I find the correct 6-digit HSN code for my product?
The CBIC’s HSN classification tool at cbic.gov.in allows you to search by product description. For manufacturing products with any ambiguity, getting a formal opinion or advance ruling before widespread invoicing is worth the cost.
Does HSN code accuracy affect my GSTR-9 filing?
Yes. The HSN summary in GSTR-9 is compiled from your invoices and returns across the year. If your invoices carry incorrect HSN codes throughout the year, GSTR-9 carries the same errors — and that’s the version auditors and the department use for annual review.
My software defaults to 4-digit HSN. Is that acceptable?
Only if your turnover is under ₹5 crore. Above ₹5 crore, 6-digit HSN is mandatory. If your software defaults to 4-digit above that threshold, you need to configure it for 6-digit — the responsibility is yours, not the software vendor’s.
References
- CGST Rules, 2017 — Rule 46 (invoice requirements including HSN code)
- CBIC Notification on HSN code requirements for different turnover slabs
- HSN Schedule as updated post-GST 2.0 (September 2025 notifications)
Last Updated: 09 July 2026
Reviewed By: TaxKitab Team
⚠️ HSN codes and their associated GST rates were updated as part of the September 2025 GST 2.0 changes. Verify every HSN against the current CBIC tariff notification — don’t assume pre-September 2025 mappings are still correct.
This HSN issue connects to ITC reversals under Rule 37 and GSTR-9/9C mistakes. See also our GST 2.0 rate structure post for how rate changes affect HSN classification decisions.
Call or WhatsApp: +91 7448200422 Email: info@taxkitab.com Website: taxkitab.com See our GST Return Filing service or Contact us. For a full manufacturing-specific GST guide, see our GST Manufacturers Book 5.
