Understanding GST Slabs in India: A Practical Guide for Small Businesses

GST isn't a single tax rate

One of the most common misunderstandings among new business owners is treating GST as one flat percentage. In reality, GST in India operates on multiple slabs, with different categories of goods and services taxed at different rates depending on their classification.

The commonly cited slabs are 5%, 12%, 18%, and 28%, alongside a nil rate for certain essential goods and services, plus special rates for specific categories like precious metals. Which slab applies to your product depends on its HSN (Harmonized System of Nomenclature) code for goods, or SAC (Services Accounting Code) for services.

Why the slab structure exists

The tiered structure reflects a policy choice: essentials and mass-consumption goods sit at lower rates, while luxury and 'sin' goods sit at the top slab. This means two businesses selling superficially similar products can face very different GST rates if their goods are classified differently — which is why checking the actual HSN code matters more than guessing from the general product category.

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

For a sale within the same state, GST splits into CGST (Central GST) and SGST (State GST), each typically at half the total rate — so an 18% slab item is 9% CGST plus 9% SGST. For a sale across state lines, the full rate is charged as IGST (Integrated GST) instead, which is later apportioned between the central and destination-state governments.

This distinction matters for invoicing: an intra-state invoice should show CGST and SGST as separate line items, while an inter-state invoice shows a single IGST line.

Finding the right rate for your product

Start from your product's HSN code, which you likely already need for invoicing purposes above certain turnover thresholds. Cross-check the applicable rate against the current official rate schedule, since rates and classifications are occasionally revised by GST Council notifications — a rate that applied last year may not be current today.

If you sell a genuinely new or unusual product and can't find a clear match, many businesses use an Advance Ruling from their state's Authority for Advance Rulings to get a binding classification, rather than guessing and risking a mismatch during an audit.

Common invoicing mistakes

The most frequent small-business errors are: applying CGST+SGST to an inter-state sale (it should be IGST), using last year's rate after a notified change, and rounding GST calculations inconsistently across invoices, which can cause reconciliation headaches at filing time.