How HSN/SAC Codes Affect GST Rate Calculation

Table of Contents 1. Introduction 2. What Is HSN & SAC Code? 3. Why Are HSN & SAC Codes Important for GST? 4. Difference Between HSN/ SAC Codes in GST 5. Using HSN/SAC Codes for Accurate GST Filing 6. Conclusion

Introduction
 

You're about to raise an invoice, and the billing screen asks for a code. Is it HSN or SAC? How many digits? And will picking the wrong one change the tax you charge?

That last question is the one that matters. In GST, the code you attach to a product or service is what points you to the right tax rate. Get it right and your invoices, returns and your customers' input tax credit all line up. Get it wrong, and you can end up with a rate difference that comes back as a tax demand, with interest.

This guide covers what HSN and SAC codes are, how they differ, how the code leads you to your GST rate, how many digits you need, and what to do if a wrong code has already gone out on an invoice.

What Is HSN and SAC Code?

HSN stands for Harmonised System of Nomenclature. It's an international system for classifying goods, used by more than 200 countries for customs and trade. Every product, from rice to machinery, gets a numeric code that describes what it is.

SAC stands for Services Accounting Code. It's India's way of classifying services under GST, since the HSN system covers goods only. Consulting, repair work, hotels and IT services each have their own SAC.

So when someone asks for the HSN SAC code full form, the short answer is: Harmonised System of Nomenclature for goods, and Services Accounting Code for services. Both do the same job in GST. They tell you exactly what you're selling, so the correct rate can be applied.

HSN Code and SAC Code: What's the Difference?

The difference between HSN and SAC code in GST comes down to what you're selling. Here's a side-by-side look:

HSN Code	SAC Code
Stands for	Harmonised System of Nomenclature	Services Accounting Code
Used for	Goods	Services
Origin	International (World Customs Organization system)	Used in India for GST
Digits	4, 6 or 8 digits in GST, depending on turnover and the type of supply	6 digits, starting with 99
Example	851712: telephones for cellular networks	998314: IT consulting and support services
Used in	Invoices and GSTR-1 for goods	Invoices and GSTR-1 for services

In plain terms, if you can pick it up, store it or ship it, it's goods and you need an HSN code. If you're doing something for someone, it's a service and you need a SAC. If your business does both, your invoices will carry both types of code.

HSN Code GST Rate: How the Code Decides Your Tax

GST rates are notified by the government against product and service classifications. The HSN or SAC code is how you find the entry that applies to you. Once you know the rate, the calculation itself is simple:

GST = taxable value × GST rate. On a ₹10,000 item at 18%, GST is ₹1,800. For a sale within your state, that splits into ₹900 CGST and ₹900 SGST. For an interstate sale, the full ₹1,800 is IGST.

So is GST calculated based on HSN codes? Not directly. The HSN or SAC code doesn't calculate the tax. It tells you which rate to use, and the rate does the rest.

The current GST rate structure

Since 22 September 2025, GST runs mainly on two rates, 5% and 18%, plus a special 40% rate for certain luxury and sin goods, alongside nil-rated items. The older 12% and 28% slabs were largely removed, and many items moved to a new rate. But not everything follows the same pattern, and some special rates and exemptions still exist.

That's why you shouldn't assume a rate from memory or from last year's invoice. Check the rate for your exact code, especially for supplies made around the changeover.

Why the code isn't always the whole story

For some goods and services, the rate also depends on the description or on conditions, such as a price band or the type of service. So use the code together with the notified description, not on its own.

How to Find GST Rate by HSN Code

There are three reliable ways to do it.

1. The GST portal's HSN search. It's free and doesn't need a login.

1. Go to the GST portal (gst.gov.in).
2. Click Services, then User Services, then Search HSN Code.
3. Search by code or by a description of the product or service.
4. Check the rate shown for your product and the date you're supplying it.

The same section lets you download the HSN directory in Excel format.

2. A quick finder tool. A tool like the Insidash HSN and SAC code finder lets you look up a code and its rate in seconds while you're billing. For high-value products or anything unusual, cross-check against the GST portal.

3. The official tariff and notifications. For specialised goods, imports and exports, the customs tariff and the GST rate notifications give you the full classification detail.

How to find the right HSN code for your product

• Start with a clear description of what you sell: what it is made of, what it does, and how it's sold.
• Search by keyword, then compare the descriptions of the codes that come up, not just their names.
• Look at the chapter and heading. Products are grouped by type, so nearby codes often cover similar items.
• If two codes seem to fit, check the notified description and ask your CA before you pick one.
• Write down why you chose the code, so you can explain it later.

How to find the SAC code for a service

The process is the same, but search the services side of the portal. Look for the category that matches the work you do, such as IT services, legal services, repair and maintenance, or accommodation. SAC codes start with 99, so a code that doesn't is probably an HSN.

How Many Digits of HSN Code Do You Need?

The number of digits depends on your turnover in the previous financial year:

• Up to ₹5 crore: at least 4 digits on B2B invoices. Sales to unregistered customers don't need the HSN digits to be mentioned.
• Above ₹5 crore: at least 6 digits on all invoices.
• Exports and imports: 8 digits.

The same rule applies when you report the HSN-wise summary of your sales in Table 12 of GSTR-1. Using more digits than the minimum is allowed, and it can reduce the chance of misclassification.

Rate Difference and HSN Code in GST: What Happens When It Goes Wrong

A rate difference arises when the GST you charged isn't the GST that should have been charged. The most common cause is a wrong HSN or SAC code. Here's how the different situations play out.

• Wrong code, same rate. There's no tax shortfall, but it's still a reporting error. Correct it so your GSTR-1 data is accurate.
• Rate charged was too low. You've short-paid tax. You may have to pay the difference with interest, and in some cases a penalty. The usual interest rate is 18% a year.
• Rate charged was too high. Your customer paid more than they should have, and you've deposited extra tax. You can fix it with a credit note, subject to the time limit for credit notes.

Charging the wrong rate on purpose is treated far more seriously than an honest slip. In either case, a quick correction and a clear record are your best protection.

How to fix a rate difference

1. Find every affected invoice. Check the code, the rate charged and the rate that should have applied.
2. Work out the difference. Note the taxable value, the tax charged and the tax that was due.
3. Choose the right document. A credit note if you overcharged, and a debit note (supplementary invoice) if you undercharged. There's no time limit for issuing a debit note, but your customer's ITC on it follows the usual time limits.
4. Report it correctly. Include the note in the return for the month you issue it, and amend the original reporting in a later GSTR-1 if needed.
5. Pay any interest due, and update the code in your billing software so it doesn't happen again.

Which HSN code do you use for a rate difference invoice?

In general, a debit note or supplementary invoice for a rate difference carries the same HSN or SAC code as the original supply, because it adjusts the value or tax of that same supply. If the original invoice itself used the wrong code, sort that out first and confirm the approach with your CA.

Read Also: HSN Code for Furniture

Common HSN and SAC Mistakes to Avoid

• Copying a code from a competitor's invoice without checking it fits your product
• Using an old code or rate after a rate revision
• Picking a code because it has a lower rate
• Using 4 digits when your turnover requires 6
• Using different codes for the same item on different invoices
• Leaving the code blank or entering a made-up one
• Mixing up HSN and SAC for businesses that supply both goods and services

Tips for Getting Your HSN and SAC Codes Right

• Create your product and service list once, with the correct code and rate for each item.
• Review that list whenever GST rates change.
• Let your billing software fill in the code and the rate automatically, so there's less typing to get wrong.
• Cross-check unusual or high-value items on the GST portal.
• Review your GSTR-1 HSN summary before you file.
• Keep notes on how you decided on a classification for anything borderline.

Conclusion

HSN and SAC codes can look like admin, but they decide something important: which GST rate applies. Pick the right code, check the current rate, use enough digits, and keep your item list tidy. Do that, and rate differences, notices and invoice corrections become rare.

If you're ever unsure about a borderline product or service, ask a CA before you bill. It's a lot cheaper than correcting a year of invoices.

FAQs

What is an HSN code in GST?

An HSN code is a numeric code that classifies goods. HSN stands for Harmonised System of Nomenclature, an international system used in more than 200 countries. In GST, it identifies what you're selling so the right tax rate can be applied.

How does an HSN code affect GST rate calculation?

The HSN code points you to the GST rate notified for that product. You then apply that rate to the taxable value to get the tax. A wrong code can lead to a wrong rate and a rate difference.

How can I find the GST rate using an HSN code?

Use the Search HSN Code option under Services and then User Services on the GST portal, or a finder tool, and enter the code or a description. Check the rate against the date of your supply, and confirm any unusual items against the official notification.

What is the difference between HSN and SAC codes?

HSN codes classify goods, while SAC codes classify services. HSN is an international system, whereas SAC is used in India for GST, and SAC codes are 6 digits starting with 99. Both are used on invoices and in GSTR-1 to determine the correct rate.

How do I find the correct HSN code for my product?

Search the GST portal or a finder tool by keyword, then compare the full descriptions of the codes that appear. Check the chapter and heading, and ask your CA if two codes seem to fit. Note down why you chose the one you did.

How can I find the SAC code for a service?

Search the services section of the GST portal's HSN and SAC search using a description of your service, such as IT consulting or repair. Pick the code whose description best matches the work you do. SAC codes always begin with 99.

Is GST calculated based on HSN codes?

Not directly. GST is calculated as the taxable value multiplied by the GST rate. The HSN or SAC code only tells you which rate applies. Using the wrong code can lead to the wrong rate and so the wrong tax.

Where can I check HSN codes on the GST portal?

Go to the GST portal, click Services, then User Services, then Search HSN Code. You can use it before or after logging in. You can also download the HSN directory in Excel format from the same page.