HSN Digits: Four, Six or Eight, and Who Decides

HSN Digits explained: this guide covers what it means, who it applies to, the step-by-step process, documents required, fees, due dates and penalties in India — so you can stay compliant with confidence and avoid costly mistakes.

The HSN code on an invoice is not a formality. It drives the rate, the e-invoice validation, the GSTR-1 summary and, increasingly, the system's own risk analysis.

How many digits you must show depends on two separate tests, and only one of them is about your size.

The proviso to Rule 46 empowers the Board, on the Council's recommendation, to notify (i) the number of HSN digits a class of registered persons must mention; (ii) a class of supply of goods or services for which a specified number of digits must be mentioned by all registered taxpayers; and (iii) the class of registered persons not required to mention HSN at all. Limb (i) is the turnover-based requirement. Limb (ii) is the commodity-based requirement, and it applies irrespective of turnover.

The turnover-based requirement

For a supplier up to ₹5 crore, HSN reporting is optional for B2C supplies and mandatory at four digits for B2B.

The reference is the preceding financial year's aggregate turnover, computed under s.2(6) across the PAN on an all-India basis. Aggregate turnover: the five things it includes →

The commodity-based requirement

This is the one businesses miss, and the ICAI FMCG sectoral guide flags it directly: 8-digit HSN reporting is not turnover-based — it applies to specified goods, such as certain chemical products, irrespective of the supplier's turnover.

The notified list covers, broadly, specified chemicals and chemical products — a schedule of tariff items on which eight-digit HSN must be shown by all registered persons supplying them.

So a small trader with ₹80 lakh turnover dealing in a listed chemical must show eight digits, while a ₹50 crore business supplying unlisted goods shows six.

The two tests are cumulative: apply the turnover requirement to everything, then override it upward for the notified commodities.

Where the digits are reported

On the invoice. Rule 46(g).

In GSTR-1, Table 12. The HSN-wise summary of outward supplies, with the digit requirement mirroring the invoice requirement. Table 12 has moved from a free-text field to a dropdown-validated field, so an HSN not in the master is rejected.

In the e-invoice schema. The IRP validates the HSN against the master and against the digit requirement for the supplier's turnover band. A wrong or short HSN fails IRN generation.

In GSTR-9. The HSN summary of outward supplies in Table 17, and of inward supplies in Table 18, with their own applicability conditions.

Why the digit count matters beyond compliance

Rate determination. Rate entries are specified at four, six or eight digits. A supply classified at four digits where the rate entry distinguishes at eight has not been classified for rate purposes at all.

Refund claims. Inverted duty refunds under Rule 89(5) are computed on turnover of inverted rated supplies, identified by HSN. An imprecise HSN makes the claim hard to substantiate.

Risk analytics. The system compares HSN-wise outward supplies against inward, and against industry norms. Consistent misclassification produces a pattern.

E-way bill validation. The e-way bill carries the HSN, and a mismatch between the invoice, the e-invoice and the e-way bill is a discrepancy on interception.

Practical notes

• Determine the digit requirement once a year, on the preceding year's aggregate turnover, and configure the ERP accordingly.
• Maintain a separate flag for notified eight-digit commodities, checked against the current notification.
• Validate the HSN master against the e-invoice and GSTR-1 masters. An HSN that is valid in your ERP but not in the portal master will fail at filing.
• Classify at the deepest level the tariff distinguishes, even where a shorter code would satisfy the reporting requirement. The rate depends on classification, not on the reporting minimum.
• Where classification is genuinely arguable, an advance ruling under s.97(2)(a) is available.
• Services use SAC, and the same reporting architecture applies.

Key takeaways

• The proviso to Rule 46 creates two separate powers — a turnover-based digit requirement and a commodity-based one.
• Up to ₹5 crore: four digits for B2B; above ₹5 crore: six digits for all supplies.
• Notified goods, including specified chemical products, require eight digits from everyone.
• The requirement flows through to GSTR-1 Table 12, the e-invoice schema and GSTR-9.
• A short HSN can fail IRN generation.
• Classification for rate purposes must go as deep as the tariff distinguishes, regardless of the reporting minimum.

Read next

• Rule 46: Every Particular a Tax Invoice Must Carry
• HSN and SAC Codes: Classification Under GST
• HSN and SAC Code Finder Guide
• Aggregate Turnover: The Five Things It Includes

Disclaimer: Positions stated as on 5 September 2026, based on the CGST Rules as amended to 31 March 2026 (ICAI Bare Law, 12th edition) and the ICAI GST Sectoral Guide on Fast-Moving Consumer Goods (2026). Verify the current notification for digit requirements and the notified eight-digit list.