HSN and SAC Codes: How to Find the Right One (and Why It Matters)

HSN (Harmonised System of Nomenclature) codes classify goods; SAC (Services Accounting Code) codes classify services. Every line item on a GST invoice needs one, because the code — not the free-text description you type — is what actually determines the applicable GST rate in the eyes of the system.

How many digits do you actually need?

The required digit count scales with turnover — smaller businesses use fewer digits, larger ones need more precision. This threshold has moved before and can move again, so treat any specific digit-count rule as something to confirm against your current turnover on the GST portal rather than a fixed fact — it's exactly the kind of rule worth double-checking each financial year rather than assuming last year's answer still holds.

How to find the right code

• Search by product/service description on the GST portal's own HSN/SAC finder rather than guessing from memory or a template.
• Match the code to what you actually sold, not the closest-sounding one — two similar-looking services can carry different SAC codes and different GST rates.
• Keep it consistent across invoices for the same product or service — a code that changes invoice to invoice for the same line item is a red flag in any reconciliation.
• Save it once, reuse it — set the HSN/SAC on your item catalogue instead of retyping it per invoice, so it can't drift by accident. This is exactly why Settle's item catalogue stores a default HSN/SAC per item.

What actually goes wrong when it's wrong

A wrong HSN/SAC code usually means a wrong GST rate gets applied — undercharging leaves you owing the difference later, overcharging means refunding a customer or issuing a credit note. It also makes your GSTR-1 filing (which is reported HSN-wise for many taxpayers) harder to reconcile against what you actually sold. See common GST invoice mistakes that trigger a compliance notice for how this compounds with other small errors.