GST & Compliance

GST Compliance for Small Businesses: A Practical Guide

If you're running a small business in India, GST touches nearly every invoice you raise. Getting the basics right matters — both for staying compliant and for your customers being able to claim input tax credit correctly.

CGST, SGST, and IGST — what's the difference?

Which tax applies comes down to one question: is the sale within the same state, or across state lines?

• Same state (intra-state): the tax splits into CGST (Central GST) and SGST (State GST), each usually at half the total GST rate.
• Different states (inter-state): IGST (Integrated GST) applies instead, at the full combined rate.

For example, an 18% GST item sold within the same state splits into 9% CGST + 9% SGST. The same item sold to a customer in a different state is billed as 18% IGST instead.

HSN and SAC codes

Every product needs an HSN (Harmonized System of Nomenclature) code, and every service needs a SAC (Services Accounting Code). These codes classify what you're selling and are required on invoices above certain turnover thresholds — and increasingly expected even below them, since they make GST return filing far easier to reconcile.

Common mistakes that cause problems later

• Guessing the customer's state: the tax treatment depends on the customer's registered state, not where the transaction physically happens. Get this wrong and you may charge CGST+SGST when IGST was actually owed, or vice versa.
• Missing or incorrect HSN/SAC codes: this is one of the most common reasons GST returns get flagged for reconciliation issues.
• Manual tax calculation: doing the CGST/SGST/IGST split by hand invites rounding errors and inconsistency across invoices, which compounds over hundreds of transactions.

Why this is worth automating

The core of GST compliance isn't complicated once you understand the logic — but doing it correctly, invoice after invoice, without a system that applies the rules automatically, is where mistakes creep in. Software that calculates the right split based on the customer's actual state, and enforces HSN/SAC codes at the point of billing, removes the manual judgment call from every single invoice.