GST came into effect in July 2017 and small business owners have had a complicated relationship with it ever since. Some find it genuinely simpler than the old system. Others feel like they spend more time filing returns than actually running their business. The truth is somewhere in between — and understanding how it actually works makes the compliance burden much lighter.
Updated: GST rates changed significantly under the GST 2.0 reform effective 22 September 2025 — the old 12% and 28% slabs were removed. The rate figures below reflect the current structure.
This is a practical guide for people running real businesses, not a textbook overview.
Do you actually need to register?
This is the first question to settle. If your annual turnover from goods is below ₹40 lakhs (₹20L in some northeastern and hill states), you don't legally need to register. For services, the threshold is ₹20 lakhs (₹10L in special category states).
But here's where it gets interesting — if you sell on Amazon, Flipkart, Meesho or any e-commerce platform, you must register regardless of turnover. Even if you made ₹50,000 last year selling sarees online, you need a GST number. E-commerce platforms won't let you list without one.
Voluntary registration is also worth considering even below the threshold. Once you're registered, you can issue proper tax invoices and claim Input Tax Credit on your purchases. Many larger businesses and government contracts require vendors to be GST registered — so if your clients are companies, registration opens more doors than it closes.
The Input Tax Credit — this is the part that actually benefits you
ITC is what makes GST genuinely fair for businesses. Whatever GST you pay on your purchases can be set off against the GST you collect from customers.
Simple example: you buy raw materials for ₹1 lakh and pay 18% GST = ₹18,000. You sell finished goods for ₹1.5 lakh and collect 18% GST = ₹27,000. You don't pay ₹27,000 to the government — you set off the ₹18,000 you already paid, and only remit ₹9,000.
Under the old system, you paid tax on tax — the VAT on your finished goods was calculated on a price that already included the tax you paid on inputs. GST fixed this. The cascading tax effect is gone, at least in theory.
GST rates — the ones you'll actually encounter
The 0% rate covers essentials: fresh vegetables, milk, eggs, books, most healthcare services. If you're in this space, you don't collect GST, but you also can't claim ITC on your purchases.
18% is where most service businesses land — IT, consulting, restaurants with AC, financial services, most professional services. If you're a freelancer or agency, your invoices most likely carry 18% GST.
5% covers most daily necessities, packaged food, and transport. 40% is the new slab for sin/luxury items — tobacco, pan masala, aerated and caffeinated drinks, luxury vehicles. Most small businesses never deal with the 40% rate. The older 12% and 28% slabs no longer exist — goods that used to sit at 12% mostly moved to 5%, and goods that used to sit at 28% moved to either 18% or 40%, depending on the item.
CGST vs SGST vs IGST — don't let this confuse you
When you sell to someone in the same state, the GST splits equally between the centre and state — so 18% becomes 9% CGST + 9% SGST on your invoice. When you sell to someone in a different state, the full 18% goes as IGST. Same total tax, different destination.
This matters for your invoice format. Intra-state invoices show CGST and SGST separately. Inter-state invoices show IGST as one line. Your GST software should handle this automatically.
Filing — the part most people dread
Regular taxpayers file GSTR-1 (sales data) by the 11th of every month and GSTR-3B (tax payment summary) by the 20th. Miss the GSTR-3B deadline and you pay interest at 18% per annum on the outstanding tax — that adds up fast.
If your turnover is below ₹1.5 crore (₹75L for service businesses), look at the Composition Scheme. You pay GST as a flat percentage of turnover (1% for traders, 5% for restaurants, 6% for services), file quarterly instead of monthly, and the compliance burden drops significantly. The downside: you can't claim ITC and you can't make inter-state sales.
One mistake I see small businesses make repeatedly
Treating GST money as working capital. The GST you collect from customers is never your money — it belongs to the government. When you collect ₹18,000 in GST, keep it in a separate account or at least mentally ring-fence it. Businesses that spend their collected GST on operations end up in serious trouble when the filing deadline arrives.
Calculate GST-inclusive and exclusive amounts instantly with our GST Calculator — it also splits CGST/SGST/IGST for you based on transaction type.