GST Classification & HSN/SAC Advisory

GST rates are specified in CGST Rate Notifications 1/2017-CT(Rate) (goods) and 11/2017-CT(Rate) (services). Goods are classified by HSN (Harmonized System of Nomenclature) — the 4/6/8-digit code determines the rate. Services are classified by SAC (Services Accounting Code). HSN/SAC must appear on invoices (6-digit mandatory for turnover above ₹5 crore; 4-digit for ₹1.5–5 crore; optional below ₹1.5 crore per Rule 46 of CGST Rules). Wrong HSN on invoices attracts a penalty of ₹50,000 under Section 125 CGST Act.

Section 8 CGST Act: a composite supply (naturally bundled, one principal supply) is taxed at the principal supply rate. Example: air ticket with in-flight meal — the passenger transport is principal; 5% applies per Notification 11/2017-CT(Rate). A mixed supply (independent supplies bundled at a single price) is taxed at the highest rate among all components per Section 8(b). Example: gift hamper with food, clothing, and cosmetics — taxed at the highest applicable rate (cosmetics 18%). This distinction directly determines the rate payable and is a recurring audit issue.

Misclassification causing short payment is recoverable under Section 73 CGST Act (bona fide error: 3-year limitation, 10% penalty of tax short paid) or Section 74 (fraud or suppression: 5-year limitation, 100% penalty). Interest at 18% p.a. accrues under Section 50 from the original due date. Sectors with large rate differentials — pharmaceuticals (0%–12%), construction services (5%–18%), food products (0%–18%), software and IT services (0%–18%) — are most frequently scrutinised. An incorrect Advance Ruling relied upon in good faith provides protection under Section 103.

Rule 46 CGST Rules mandates HSN/SAC on invoices at the turnover thresholds above. GSTR-1 Table 12 requires HSN-wise summary of outward supplies for the period. The GST system cross-matches the HSN declared in Table 12 against the rates applied in Table 4/6 — a mismatch between the declared HSN and the rate used is an automated scrutiny trigger under Section 61 (Scrutiny of Returns). For businesses with multiple product lines or variable rates, a documented HSN master register is necessary to defend any subsequent notice.

Apply the General Rules of Interpretation (GRI) of the Customs Tariff Act 1975 (adopted into the GST HSN schedule by Section 2(45) CGST Act): GRI Rule 1 classifies by heading terms; GRI Rule 4 assigns to the most similar goods. CBIC Circulars and Authority for Advance Rulings (AAR) rulings are authoritative for disputed classifications. For new products — AI-generated outputs, biodegradable composites, software-hardware bundles — an Advance Ruling application under Section 97 CGST Act before commercial launch is strongly advisable; the ruling binds both the applicant and the jurisdictional officer under Section 103.