How Many HSN Code Digits Must Your GST Invoice Show?

Every GST tax invoice for goods must show an HSN code, and every service invoice must show a SAC code. But how many digits? Two, four, six or all eight? The answer depends on your turnover, and getting it wrong can trigger warnings in GSTR-1 and errors in e-invoicing. This guide explains the digit rule, how the GST portal now checks it, and how to set it up correctly.

If you are new to the concept itself, start with what is HSN code.

What is the legal rule on HSN digits?

The requirement comes from Notification No. 78/2020-Central Tax, dated 15 October 2020, issued under Rule 46 of the CGST Rules, which lists the particulars a tax invoice must contain. The notification ties the number of HSN digits to your aggregate annual turnover (AATO) in the preceding financial year:

AATO in previous financial year	Minimum digits on tax invoice
Up to ₹5 crore	4 digits of HSN/SAC
More than ₹5 crore	6 digits of HSN/SAC

The GST Network's advisories describe the same split for reporting in Table 12 of GSTR-1, saying it is mandatory to report a "minimum 4 digit or 6 digit of HSN Code" on the basis of AATO in the preceding financial year.

Note the word minimum. You may print more digits. Nobody will penalise you for an accurate 8-digit code.

What do 2, 4, 6 and 8 digits actually tell you?

Each extra pair of digits narrows the product description. Using a mobile phone as an example:

Digits	Code	Level	Meaning
2	85	Chapter	Electrical machinery and equipment
4	8517	Heading	Telephone sets, including smartphones, and other apparatus for transmitting voice or data
6	8517 13	Sub-heading	Narrower international group
8	8517 13 00	Tariff item	Indian national tariff line

For GST rates, many entries in the rate notifications are written at the 4-digit heading level ("8517 — All goods", in Schedule II at 18% from 22 September 2025). Others are written at 6 or 8 digits when the government wants a different rate for a narrow product. For example, the rate notification lists "2202 99 30 — Beverages containing milk" at 5%, while "2202 10 — aerated waters containing added sugar" sits in the 40% schedule. In such cases a 4-digit code alone (2202) would not tell you which rate applies, which is one reason to use more digits than the minimum.

How does the GST portal check HSN digits in GSTR-1?

The portal has rolled out HSN validation in phases:

1. Phase 1 (2022): Taxpayers above ₹5 crore had to report 4 digits and later 6 digits, while smaller taxpayers reported at least 2 digits. Manual entry was allowed with warnings.
2. Phase 2 (from 1 November 2022): Taxpayers up to ₹5 crore must report 4 digits; those above ₹5 crore must report 6 digits.
3. Phase 3 (from the May 2025 return period): Manual typing of HSN is not allowed. The code must be selected from a drop-down, and a "Description as per HSN Code" is auto-filled. Table 12 is split into B2B Supplies and B2C Supplies tabs, and value checks compare Table 12 with other tables (initially in warning mode).

The portal also provides a "Download HSN Codes List" button in Table 12, which gives the HSN and SAC master it validates against. If a code you use is not in that list, you will not be able to select it, so your invoice codes and your return codes must match the portal's master.

For filing steps, see the GSTR-1 filing guide.

Worked example: same business, two years

A Coimbatore textile trader sells cotton fabric and readymade shirts.

FY 2025-26: AATO was ₹3.8 crore. For invoices in FY 2026-27, the trader must show at least 4 digits.

Item	HSN shown (4-digit minimum)	Rate	Taxable value	IGST (inter-state sale)
Woven cotton fabric	5208	5%	₹1,20,000	₹6,000
Men's cotton shirts, ₹900 each × 100	6205	5%	₹90,000	₹4,500
Total			₹2,10,000	₹10,500

Both items fall in Schedule I (5%) of Notification 9/2025: woven cotton fabrics (5208 to 5212) and apparel of Chapter 62 with a sale value not exceeding ₹2,500 per piece.

FY 2026-27: sales grow to ₹5.6 crore. From 1 April 2027, the trader must show at least 6 digits on every invoice and in Table 12. The trader updates the item master to 6-digit codes before 1 April so that every invoice, credit note and the GSTR-1 summary switch on the same day.

The tax calculation does not change because of the extra digits. What changes is the precision of classification and the risk of a mismatch if the item master is not updated.

How does the digit rule interact with e-invoicing and e-way bills?

E-invoices are generated by businesses above the notified turnover threshold, which is well above ₹5 crore AATO, so in practice most e-invoicing businesses are already on the 6-digit requirement. The e-invoice schema validates the HSN against the master list, and a code that does not exist in that list gets rejected.

E-way bills also ask for the HSN in Part A. Use the same code you print on the invoice, so the documents match at a roadside check.

The key principle: one item, one HSN code, everywhere — invoice, e-invoice, e-way bill, and GSTR-1.

How do I set up the right number of digits in my billing system?

1. Check last year's AATO across all GSTINs on the same PAN.
2. Decide your digit level: 4 if AATO was ₹5 crore or less, 6 if more. Consider using 6 or 8 anyway if you deal in products where rates differ at sub-heading level.
3. Download the HSN list from the GSTR-1 Table 12 screen to make sure your codes exist in the portal master.
4. Update every item in your item master, including inactive items that might be reused.
5. Map the unit (UQC) for each item, because Table 12 reports quantity by unit.
6. Test one invoice and one credit note to confirm the codes print correctly.
7. Review yearly before 1 April, and whenever a rate notification is amended.

Billing Software by Betterwork keeps HSN/SAC on each item and builds the HSN-wise summary automatically from your invoices and credit notes, so the Table 12 figures come from the same data you billed with.

How do I calculate AATO for the digit test?

Aggregate annual turnover is not just your sales figure in the books. For GST it is computed on an all-India basis for the same PAN, and broadly includes:

• Taxable supplies (B2B and B2C)
• Exempt supplies
• Exports of goods and services
• Inter-state supplies, including stock transfers between your own GSTINs in different states

It excludes the GST itself (CGST, SGST, UTGST, IGST and cess) and inward supplies on which you paid tax under reverse charge.

A quick example. A Surat business has two GSTINs (Gujarat and Maharashtra) under one PAN. In FY 2025-26:

Component	Gujarat GSTIN	Maharashtra GSTIN
Taxable outward supplies	₹3.1 crore	₹1.4 crore
Exempt supplies	₹0.2 crore	—
Exports	₹0.6 crore	—
Subtotal	₹3.9 crore	₹1.4 crore

AATO = ₹3.9 crore + ₹1.4 crore = ₹5.3 crore. Even though neither GSTIN alone crosses ₹5 crore, the PAN-level total does, so both GSTINs must use at least 6-digit HSN from 1 April 2026. This catches many multi-state businesses by surprise.

What about B2C invoices and small retail bills?

For businesses with AATO up to ₹5 crore, Notification 78/2020 framed the 4-digit requirement around supplies to registered persons, and the notification text gives the government power to relax it for B2C supplies. In practice:

• B2B invoices: always show at least the required digits.
• B2C invoices: check the current notification text for your turnover band, but printing HSN on B2C bills is simple and avoids doubt.
• GSTR-1 Table 12: has a separate B2C tab. The advisory notes that the B2C tab currently accepts values more flexibly than the B2B tab, but the HSN codes you report should still match what you sell.

The easiest operating rule for a shop is: one item master, the same HSN on every bill, B2B or B2C.

Does HSN go on every document, or only tax invoices?

Rule 46 lists HSN as a particular of the tax invoice. Other GST documents have their own rules, and most of them also carry HSN in practice:

Document	HSN practice
Tax invoice	Required at the notified digit level
Bill of supply	Commonly shown; check the rule for your case
Credit / debit note	Needed so Table 12 can be netted correctly
Delivery challan	Shown for identification of goods
E-invoice	Mandatory HSN field per line
E-way bill	HSN entered in Part A

Quick check before you file GSTR-1

1. Confirm every item in your HSN summary has a code with the required number of digits.
2. Make sure the same code appears on the invoice, the e-invoice and the summary.
3. Check that B2B and B2C rows are reported in the correct tabs of Table 12.

Common mistakes

• Printing only the chapter (2 digits). That was a transitional portal phase, not the invoice rule. You need at least 4.
• Using 4 digits when the rate depends on a 6- or 8-digit split. You may meet the minimum but still charge the wrong rate.
• Typing codes that are not in the portal master. From the May 2025 return period, Table 12 only accepts drop-down selection.
• Different codes on invoice and return. Staff sometimes "tidy" codes in the return; that creates mismatches.
• Forgetting credit notes. Table 12 values are net of credit and debit notes, so those documents need correct HSN too. See mandatory fields on a GST invoice for the rest of the invoice checklist.
• Not revisiting after crossing ₹5 crore. The switch to 6 digits starts with the next financial year.

Key takeaways

• The minimum is 4 digits for previous-year AATO up to ₹5 crore and 6 digits above ₹5 crore.
• The same rule covers SAC codes on service invoices.
• You may always show more digits; precision often helps with rate accuracy.
• GSTR-1 Table 12 now uses drop-down HSN selection with separate B2B and B2C tabs.
• Keep a single item master so invoices, e-invoices, e-way bills and returns use identical codes.

This guide is general information, not tax advice. Rules last checked on 20 October 2026; confirm with your tax professional for your situation.