How to Add HSN Code in GST Portal After Registration?

HSN stands for Harmonized System of Nomenclature , a globally standardized system developed by the World Customs Organization (WCO) to classify goods. India adopted this system under GST to ensure uniform tax treatment across products and services. For services, the equivalent code is SAC (Service Accounting Code). The HSN or SAC code in the GST registration determines which tax rate applies to each product or service the business supplies.

An incorrect or missing HSN code creates mismatches between invoices, GSTR-1 Table 12 (the HSN summary table), e-invoices, and e-way bills. In GSTR-1 Table 12, taxpayers must now select the HSN code from a dropdown instead of entering it manually, and the portal cross-validates the reported values with the corresponding supply details. These mismatches can trigger validation issues, notices, and audit flags, but they do not automatically block input tax credit for the recipient.

After the GST rate rationalization in September 2025, many businesses needed to re-check their HSN-to-rate mapping, making accurate HSN codes more important than ever in 2026.

How Many Digits are Required in the HSN Code?

The number of HSN digits you must report depends on your aggregate turnover in the previous financial year. If you report fewer digits than the rule requires, your GSTR-1 filing will show errors at the validation stage.

For example , a trader dealing in cotton T-shirts reports HSN 6109 at the 4-digit level. Once the applicable requirement calls for greater detail, the business must report the corresponding 6-digit HSN, such as HSN Code 610910 . For imports and exports, the business must report the applicable 8-digit HSN, irrespective of its turnover.

If your turnover crosses the ₹5 crore threshold partway through the year, you must upgrade your HSN codes to 6 digits before you file the returns for the period in which you crossed it. Continuing to file 4-digit codes after crossing the threshold is a common mistake, and it usually surfaces during departmental scrutiny.

The GST portal collects these details during registration so businesses can maintain accurate information about their activities, products, and services. When you need to update any registration details later, the portal classifies the fields as either core or non-core. This classification determines whether a GST officer must review the amendment and how quickly the change takes effect.

The GST portal classifies all registration details into two categories under Section 28 of the CGST Act, 2017, read with Rule 19 of the CGST Rules, 2017 . Knowing this classification is important as it affects how soon HSN code updates take effect:

1. Core fields include the legal name of the business (if PAN remains unchanged), principal place of business, and addition or deletion of partners or directors. Changes to core fields require a GST officer’s review and approval within 15 working days . If the officer does not act within this period, the amendment is considered automatically approved.
2. Non-core fields cover HSN and SAC codes, trade name, email address, mobile number, bank account details, minor changes to additional places of business, and authorized signatory. Updates to non-core fields become effective immediately after submitting Form GST REG-14 with DSC or EVC verification. Officer review is not required for these changes.

Since HSN codes sit in the non-core category, adding a new one or correcting an existing code takes far less time than most taxpayers expect. The update applies to your future invoices and returns as soon as you submit it.

Follow these steps to add a new HSN code in the GST portal using the Amendment of Registration Non-Core Fields pathway:

Step 1: Log In to the GST Portal

Visit gst.gov.in and log in using the GSTIN and password. Make sure the account has the necessary access rights for an authorized signatory. If you are using a Digital Signature Certificate (DSC), ensure it is properly installed on your device and the browser plugin is active before proceeding.

Step 2: Access the Amendment of Registration Non-Core Fields Section

On the dashboard, go to Services, then select Registration, and click on Amendment of Registration Non-Core Fields. The portal opens the editable registration form. This is the correct pathway for all HSN code changes.

Do not use the Amendment of Registration Core Fields for this purpose.

Step 3: Open the Goods and Services Tab

Inside the non-core amendment form, locate and click on the Goods and Services tab. This tab lists all the HSN and SAC codes currently entered in the GST registration.

The existing codes appear in a table format, and the Add button is visible at the bottom of the list.

Step 4: Add the New HSN or SAC Code

Click Add to enter the new code. The portal presents fields for the HSN code number, a description of the goods, and the unit of measurement. Enter the HSN code with the correct number of digits based on the turnover threshold.

For service providers, enter the SAC code in the same field. Review the description carefully as it must match the actual goods or services supplied. Click Save and Continue after entering all details.

Step 5: Enter the Reason for Amendment

The portal requires a reason for the amendment before submission. Enter a clear, factual reason, such as adding a new product line or the HSN code was entered incorrectly at registration. The reason is visible to the system and may be reviewed if any query arises later. This is a required field and cannot be left blank.

Step 6: Select the Authorized Signatory

On the Verification tab, select the authorized signatory for the submission. The name and designation of the signatory must match the details already registered on the GST portal. Read the declaration on the verification page before confirming.

Step 7: Submit Using DSC or EVC

Submit the application using either a Digital Signature Certificate (DSC) or an Electronic Verification Code (EVC), depending on the entity type. Companies and LLPs are required to use DSC. Proprietorships, partnership firms, and individuals may use EVC, which is sent to the registered mobile number.

After successful submission, the portal generates an Application Reference Number (ARN). The new HSN code reflects in the GST registration almost immediately, though the updated registration certificate may take a few minutes to generate.

Note: The GST portal currently allows a maximum of 5 HSN codes under each broad category in the Goods and Services tab. If a business supplies more than five products, it can declare its top five HSN codes in the registration. For example, a business supplying 40 products can declare its top five HSN codes and still raise invoices under the other 35 products.

Adding the HSN code does not update past filings or invoices you have already generated. The following actions are required after the amendment is approved:

• Update all invoice templates and billing software so that every invoice you raise after the amendment date carries the new HSN code.
• Match the HSN code across three places:

1. 1. Your GST registration
   2. Each invoice
   3. and GSTR-1 Table 12

When the registration and GSTR-1 mismatch, the department often reads it as an audit trigger.

• If you use the e-invoice system, ensure that your invoices carry the correct HSN code. An incorrect or inconsistent HSN code can cause errors when you generate e-invoice GST documents.
• If you crossed the ₹5 crore turnover threshold and are updating from 4-digit to 6-digit codes, apply the 6-digit codes to every invoice from the start of the return period. Do not apply the new code only from the date of the amendment.

Most HSN code issues arise not from the amendment itself but from the mistakes that follow, so avoid the following:

• Using a 4-digit code after crossing the ₹5 crore turnover threshold. This creates a mismatch in GSTR-1 Table 12 and can invite notices during scrutiny.

• Using outdated codes after a rate revision. When you bill invoices under pre-revision HSN codes, they clash with your GSTR-1 entries. After the September 2025 GST rate rationalization , check that your registered HSN codes still match the current rate schedule.
• Adding HSN codes through the Core Fields pathway. HSN codes are non-core fields, so taking the wrong route only causes confusion and fails to update the codes correctly.
• Skipping the billing software update after the portal amendment. The change you make on the portal means nothing for your invoices if your accounting or billing system keeps pulling the old code.
• Copying HSN codes from unverified third-party websites. Always confirm a code on the official CBIC HSN search tool at cbic-gst.gov.in before you enter it in the GST portal.

Adding an HSN code after GST registration is a simple seven-step process with no officer approval or government fee. As a non-core amendment under Section 28 of the CGST Act, 2017, the change takes effect after DSC or EVC submission. The applicable HSN digit requirement is 4 digits for turnover up to ₹5 crore and 6 digits for turnover above ₹5 crore.

After the amendment, the new HSN code should be used consistently across invoices, billing software, e-invoices, and GSTR-1 Table 12 to avoid mismatches and compliance issues.