# What Is an HSN or SAC Code? Why the Wrong One Blocks ITC **Category:** GST | **Published:** 2026-06-25 | **Last reviewed:** 2026-06-25 | **Author:** Mrs. Swapna Patel An HSN code (Harmonized System of Nomenclature) classifies goods, and a SAC code (Services Accounting Code) classifies services, for GST. The code on each invoice line decides the GST rate that applies. Rule 46 of the CGST Rules makes HSN/SAC a mandatory field, with the required number of digits rising with turnover. A wrong code means a wrong rate, a return mismatch, and a risk to the buyer's input tax credit. > **Myth:** The HSN code on an invoice is a formality, so any close-enough code will do. > > **Fact:** The HSN or SAC code fixes the GST rate on the line. A wrong code is a wrong rate, which creates a mismatch that can stall your buyer's input tax credit. It is a mandatory field under [Rule 46 of the CGST Rules](https://www.cbic.gov.in/htdocs-cbec/gst/cgst-rules-as-amended). ## What is an HSN or SAC code? > **Short answer:** An HSN code classifies goods and a SAC code classifies services for GST. The code on a line decides its tax rate, and [Rule 46 of the CGST Rules](https://www.cbic.gov.in/htdocs-cbec/gst/cgst-rules-as-amended) makes it a mandatory field on a tax invoice. HSN stands for Harmonized System of Nomenclature, the international system used to classify traded goods. SAC stands for Services Accounting Code, the equivalent for services. GST hangs the tax rate on these codes: pick the code, and you have picked the rate. That is why the field is not cosmetic. ## How many digits do you need? > **Short answer:** The number of HSN digits required rises with your aggregate turnover, so a small seller shows fewer digits than a large one. - Businesses with lower aggregate turnover quote fewer HSN digits; larger businesses quote more, with up to 8 digits at the top end. - The digit requirement has been tightened over time, so confirm the current rule for your turnover band before relying on a 4-digit code. - SAC codes for services follow the same idea: more digits give a more precise classification of the service. **[See where HSN/SAC sits among all Rule 46 fields](https://hrareceipt.in/atlas/gst-tax-invoice-rule-46-field-anatomy)** ## Why does a wrong code block ITC? > **Short answer:** Because the code sets the rate, a wrong HSN or SAC means a wrong tax amount, which creates a mismatch when the invoice is reported, and a mismatched invoice puts the buyer's [input tax credit](/answers/what-is-input-tax-credit-itc) at risk. - A wrong code can carry a wrong GST rate, so the tax charged does not match what the goods or service should attract. - The mismatch shows up when the seller's return and the buyer's claim are compared, and the buyer's credit can be held up. - Under e-invoicing, an invalid code can cause the Invoice Registration Portal to reject the invoice outright, so it never gets a valid IRN. ## How do you find the right code? > **Short answer:** Match the goods or service to its classification on the [CBIC GST portal](https://www.cbic.gov.in/htdocs-cbec/gst/index), then reuse it consistently across invoices. - Identify what you are selling precisely; "consulting" and "software development" are different services with different SAC codes. - Use the official classification rather than guessing, since a near-miss code can still carry the wrong rate. - Keep a fixed code per product or service so every invoice classifies the same supply the same way. **[Generate a pakka bill with the right code in 60 seconds](https://hrareceipt.in/pakka-bill)** ## Primary sources - [Rule 46, Central Goods and Services Tax Rules 2017 — CBIC](https://www.cbic.gov.in/htdocs-cbec/gst/cgst-rules-as-amended) — HSN/SAC code is a mandatory particular on a tax invoice. - [HSN / SAC under GST — CBIC GST portal](https://www.cbic.gov.in/htdocs-cbec/gst/index) — Classification of goods and services and digit requirements by turnover. - [Section 16, Central Goods and Services Tax Act 2017 — CBIC](https://www.cbic.gov.in/htdocs-cbec/gst/cgst-act) — Input tax credit depends on a valid invoice, including correct classification. ## Related - [GST tax invoice fields under Section 31 and Rule 46](https://hrareceipt.in/answers/gst-tax-invoice-fields-section-31-rule-46) - [What is input tax credit — what a wrong code puts at risk](https://hrareceipt.in/answers/what-is-input-tax-credit-itc) - [What is a pakka bill — the GST invoice that counts as valid](https://hrareceipt.in/answers/what-is-a-pakka-bill) - [How to upgrade from a kaccha bill to a pakka bill (GST invoice)](https://hrareceipt.in/answers/how-to-upgrade-kaccha-bill-to-pakka-bill) --- *Source: [What Is an HSN or SAC Code? Why the Wrong One Blocks ITC](https://hrareceipt.in/answers/what-is-hsn-sac-code) — HRAReceipt.in* *This Markdown mirror is published for AI-crawler ingestion. The canonical HTML page is the definitive version.*