HSN Code on GST Invoices: 4, 6 or 8 Digits — What You Need

Every product on a GST invoice carries a number, and that number decides the rate of tax. It is the HSN code — Harmonised System of Nomenclature — and it is the single most consequential field on an invoice that most small businesses copy from a supplier and never check.

This guide covers how HSN codes are built, how many digits your invoices must show at your turnover, how to classify a product correctly, and why every code checked before September 2025 deserves a second look.

What an HSN code is

The Harmonised System is an international classification of goods maintained by the World Customs Organization. More than 200 countries use it for customs, which means a given product has the same first six digits whether it is declared in Mumbai, Rotterdam or Singapore.

India uses the same system twice: for customs duty on imports and exports, and under GST to decide the tax rate on domestic supplies. The GST rate schedules are written against HSN headings, so when you pick a code you are, in effect, picking the rate.

How the digits are structured

An HSN code narrows down from broad to specific, two digits at a time:

The first six digits are identical worldwide. India adds two more for its own customs tariff (often called ITC-HS), which is why import and export documents carry eight digits while most GST invoices need fewer.

How many digits your invoice needs

Since 1 April 2021, the number of HSN digits a GST invoice must show depends on your aggregate turnover in the previous financial year:

Two practical points. First, the threshold is checked against the previous year, so a business that crosses ₹5 crore this year moves to six digits from the next financial year. Second, nothing stops a smaller business from using six or eight digits — and doing so is often sensible, because the four-digit heading can cover products taxed at different rates. The extra digits remove the ambiguity.

Exports and imports follow customs rules, which use the full eight-digit code. The GST invoice format guide covers the other mandatory fields.

SAC codes for services

Services are classified with SAC — Services Accounting Codes — which India built on the same pattern. Every SAC code starts with 99 (chapter 99 is reserved for services), followed by a heading and group that identify the service. Information technology services sit under 9983 and accommodation services under 9963, for example.

The digit requirements for SAC on invoices mirror those for HSN: four digits up to ₹5 crore turnover for B2B supplies, six above.

HSN in your GSTR-1 return

The same codes have to be reported in Table 12 of GSTR-1, the HSN-wise summary of outward supplies — quantity, taxable value and tax for each code you sold under. The same 4-or-6-digit rule applies.

The GST portal has tightened this table over several phases. Codes are now chosen from a validated list rather than typed freely, and the summary is split between supplies to registered and unregistered buyers. The practical effect is that an invalid or outdated code, which might once have slipped through, now stops the return until it is fixed. Keep your item master clean and the return files itself.

How to classify a product correctly

Classification is a legal exercise, not a search-engine one. A sensible order of work:

1. Describe the product by what it is, not what you call it. "Herbal face pack" tells you less than "cosmetic preparation for the care of the skin, in powder form".
2. Find the chapter, then the heading. Chapter notes and section notes in the tariff are binding: they often say which chapter a product cannot go in.
3. Apply the General Rules of Interpretation when two headings seem to fit — in short, the most specific description wins, and mixtures and sets are classified by the component that gives them their essential character.
4. Check the GST rate schedule for that heading. Some headings are split by price, use or form, so the same four digits can carry two rates.
5. Record why you chose it. A one-line note in your item master is your defence if the classification is ever questioned.

The HSN code finder is a fast starting point for common goods and services. For anything borderline — composite products, kits, items that changed form — confirm on the official GST portal or with a professional, and consider an advance ruling if the amount at stake is large.

Why GST 2.0 means checking every code again

From 22 September 2025, GST moved to two main slabs, 5% and 18%, plus 40% for luxury and sin goods, and the 12% and 28% slabs were removed. Rates are attached to HSN headings, and the headings did not all move together: butter and ghee went from 12% to 5%, soap and toothpaste from 18% to 5%, air conditioners and cement from 28% to 18%, while larger cars and aerated drinks moved to 40%. The GST changes guide lists the main moves.

For a business, this means three things:

• Your item master's rates are suspect if they were set before September 2025. Re-check each HSN against the current schedule, not against the old slab it used to sit in.
• Old invoices are not wrong for supplies made before the change; the rate in force on the date of supply applies. Do not "correct" them.
• Supplier invoices may lag. If a supplier is still charging the old rate on a reduced item, your input tax credit is limited to the correct tax — raise it with them.

What a wrong code costs

A wrong HSN code is rarely a problem on its own; the problem is the wrong rate it brings with it.

• Rate too low: the shortfall becomes a demand with interest, plus penalty — and you cannot recover the extra tax from customers after the fact.
• Rate too high: your price is uncompetitive and your buyers' input credit may be questioned. Excess tax collected from customers is not simply refundable to you.
• Missing or invalid code: a general penalty can apply even where the tax was right, and the GSTR-1 HSN table will not accept it.

The fix is unglamorous: one clean item master, with the code, the rate, the date you last checked it and why you chose it. Re-check it whenever the GST Council changes rates, and your invoices, returns and input credit all stay consistent.