What is GST? A Complete Beginner's Guide
If you have ever looked at a restaurant bill and wondered why a small line called “CGST” and “SGST” is added at the bottom, you have already met GST. But what is GST, really? Why did India replace over a dozen indirect taxes with this single system in 2017? And if you run a business or plan to start one, when do you actually have to register for it?
This guide is written for absolute beginners. No jargon, no heavy legal language. By the end, you will understand what GST is, how it works, what the 2026 rate structure looks like after the GST 2.0 reforms, when registration becomes mandatory, and how to stay compliant without losing sleep.
We are CleverCoins, a tax consultancy based in Mumbra, Thane, that has helped hundreds of small businesses file returns, register for GST, and stay compliant for over five years. Let’s get started.
What is GST? The Simple Definition
GST stands for Goods and Services Tax. It is a single, destination-based, indirect tax levied on the supply of goods and services across India. It was introduced on 1st July 2017 under the slogan “One Nation, One Tax,” and it replaced a long list of overlapping central and state taxes.
Three words in that definition do the heavy lifting:
- Single — before GST, a business had to deal with VAT, service tax, excise duty, entry tax, octroi, luxury tax, and more. GST rolled most of these into one tax.
- Destination-based — GST is collected by the state where the goods or services are finally consumed, not where they are produced.
- Indirect — the tax is collected by the seller from the buyer and then paid to the government. The final burden sits with the end consumer.
Why Was GST Introduced?
Before GST, India’s indirect tax system had one big problem: tax on tax. A product would be taxed at the factory (excise), again when sold to a wholesaler (VAT), again when moved across state borders (CST), and sometimes again at the city limits (octroi). Each layer added cost, and businesses could not claim credit for most of these taxes. Consumers paid the price.
GST fixed this by:
- Creating a unified national market so goods move freely between states
- Allowing businesses to claim Input Tax Credit (ITC) on taxes already paid — removing the cascading effect
- Bringing more businesses into the formal economy through mandatory digital invoicing and returns
- Making compliance more transparent via the GSTN portal
How GST Works: The ITC Magic
Here is a simple example that explains why GST is actually business-friendly once you understand it.
Imagine you run a small furniture shop. You buy wood from a supplier for Rs. 10,000 + 18% GST (Rs. 1,800). You use it to make a chair that you sell for Rs. 15,000 + 18% GST (Rs. 2,700).
Without GST’s ITC system, you would pay Rs. 2,700 to the government as tax. But under GST, you can claim Input Tax Credit for the Rs. 1,800 you already paid on wood. So your actual tax liability is only Rs. 2,700 minus Rs. 1,800 = Rs. 900.
Key takeaway: GST taxes only the value you add. That is why keeping proper purchase invoices and filing returns correctly matters — every missed invoice is money you are losing to the government.
The Four Types of GST in India
This is where most beginners get confused. India has four types of GST, but you only deal with two or three depending on your transaction.
1. CGST (Central GST)
Collected by the Central Government on intra-state supplies (within the same state). If you sell something in Maharashtra while registered in Maharashtra, CGST applies on half the tax.
2. SGST (State GST)
Collected by the State Government on the same intra-state supply. It covers the other half of the tax.
3. IGST (Integrated GST)
Collected by the Central Government on inter-state supplies (from one state to another) and imports. If your Thane-based business sells to a client in Bangalore, IGST applies on the full tax.
4. UTGST (Union Territory GST)
Collected by the Union Territory administration on supplies within a UT without its own legislature (Chandigarh, Lakshadweep, etc.). It works like SGST.
Quick rule: CGST + SGST (or UTGST) for same-state sales. IGST for different-state sales. The total tax rate is always the same — it is just split differently.
GST Rate Slabs in 2026 (After GST 2.0)
In September 2025, the 56th GST Council meeting introduced a major rationalisation known informally as “GST 2.0.” The earlier five-slab structure (0%, 5%, 12%, 18%, 28%) was replaced with a cleaner set of slabs, effective from 22nd September 2025.
Here is what the rate structure looks like today:
GST Rate | Typical Category | Examples |
0% (Nil) | Essential goods & services | Fresh milk, eggs, fruits, vegetables, unbranded flour, education services, healthcare, UHT milk, paneer, roti, individual life & health insurance, 33 life-saving drugs |
5% | Common-use & priority items | Packaged food, edible oils, footwear up to Rs. 2,500, toothpaste, soap, medicines, electric vehicles, restaurant services (non-AC), transport services |
18% | Standard rate (most goods & services) | Mobile phones, laptops, ACs, small cars, TVs up to a certain size, cement, professional services, IT services, telecom, financial services |
40% | Luxury & sin goods | Premium cars, yachts, aerated drinks, pan masala, high-end consumer durables (tobacco products currently remain at 28% plus cess until compensation dues are settled) |
Special | Niche rates | 3% on gold & jewellery, 0.25% on rough diamonds, 1.5%/5%/6% under Composition Scheme |
The goal of GST 2.0 is to reduce classification disputes, make daily essentials cheaper, and give businesses a simpler invoicing structure. Most household items and small-ticket services have seen rate reductions.
Who Needs to Register for GST?
GST registration becomes mandatory once your aggregate annual turnover crosses the prescribed threshold. The limits depend on what you sell and where your business is located.
Type of Business | Normal States | Special Category States* |
Supplier of goods | Rs. 40 lakh annual turnover | Rs. 20 lakh annual turnover |
Supplier of services | Rs. 20 lakh annual turnover | Rs. 10 lakh annual turnover |
Mixed (goods + services) | Rs. 20 lakh annual turnover | Rs. 10 lakh annual turnover |
*Special category states include Arunachal Pradesh, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim, Tripura, Uttarakhand, and a few others.
When registration is mandatory regardless of turnover
- You make inter-state taxable supplies (selling across state borders)
- You sell through an e-commerce platform like Amazon, Flipkart, or Meesho
- You are a non-resident taxable person supplying in India
- You are liable to pay tax under the Reverse Charge Mechanism
- You are an input service distributor or an agent of another supplier
Common mistake: Many small online sellers wait to cross the turnover threshold before registering. Because you are selling on a marketplace, GST registration is mandatory from rupee one. Get this right at the start.
How to Register for GST: Step-by-Step
- Visit the official GST portal at gst.gov.in and click on “Services → Registration → New Registration.”
- Fill in Part A of Form GST REG-01 with your PAN, mobile number, and email. You will receive an OTP and a Temporary Reference Number (TRN).
- Log back in using the TRN and complete Part B by submitting business details, promoter details, principal place of business, bank details, and authorised signatory information.
- Upload scanned documents: PAN, Aadhaar, business address proof, photographs, bank statement or cancelled cheque, and the authorisation letter.
- Submit using DSC (for companies/LLPs) or EVC via Aadhaar OTP. You will receive an Application Reference Number (ARN).
- Your GST Registration Certificate (Form GST REG-06) is usually issued within 7 working days. Your 15-digit GSTIN is generated at this stage.
Pro tip: Aadhaar authentication of the promoter speeds up the process significantly. Without it, physical verification of the premises may be required, which adds a week or more.
GST Returns: What You Have to File
Once you are registered, filing returns is not optional. Even if you had no sales in a month, you still need to file a nil return. Here are the main returns you will encounter as a small business.
Return | Purpose | Frequency / Due Date |
GSTR-1 | Details of all outward supplies (sales invoices) | Monthly (11th of next month) or Quarterly under QRMP |
GSTR-3B | Summary return of sales, purchases, ITC claimed and tax paid | Monthly (20th of next month) or Quarterly under QRMP |
CMP-08 / GSTR-4 | For taxpayers under the Composition Scheme | CMP-08 quarterly; GSTR-4 annually (30th June) |
GSTR-9 | Annual consolidated return | Yearly (31st December of following FY) |
GSTR-9C | Reconciliation statement for businesses above turnover threshold | Yearly (31st December of following FY) |
Late filing attracts a penalty of Rs. 50 per day (Rs. 20 per day for nil returns) plus 18% annual interest on any unpaid tax. Small penalties add up fast if you ignore them.
The Composition Scheme: A Simpler Option for Small Businesses
If your annual turnover is up to Rs. 1.5 crore (Rs. 75 lakh in special category states), you can opt for the Composition Scheme. Instead of charging GST on invoices and claiming ITC, you pay a flat, low rate on your total turnover.
- Manufacturers and traders: 1% of turnover
- Restaurants (not serving alcohol): 5% of turnover
- Other service providers (up to Rs. 50 lakh turnover): 6% of turnover
The trade-off: you cannot claim Input Tax Credit, cannot issue tax invoices (only bills of supply), and cannot make inter-state sales. It is ideal for small local shops, kirana stores, and neighbourhood service providers with straightforward books.
HSN and SAC Codes: The Labels on Your Invoice
Every product and service under GST has a classification code.
- HSN (Harmonised System of Nomenclature) — a 4 to 8 digit code used for goods. Used globally and adopted by India in 1986.
- SAC (Services Accounting Code) — a 6-digit code used for services.
Your turnover decides how many digits you need to mention on invoices — businesses with turnover above Rs. 5 crore typically need 6-digit HSN codes. Using the wrong code is one of the most common reasons for ITC mismatches and GST notices, so classification matters more than most business owners realise.
E-way Bill: For Moving Goods
When you transport goods worth more than Rs. 50,000 across state lines (and in some cases, within the same state), you need to generate an e-way bill on the ewaybillgst.gov.in portal before dispatch. It contains details of the consignor, consignee, goods, and vehicle.
Moving goods without a valid e-way bill can result in detention of the vehicle, seizure of goods, and a penalty equal to the tax amount. If you are in e-commerce, manufacturing, or wholesale, this is non-negotiable.
Benefits of GST for Small Businesses
- One registration across India — no more separate VAT, service tax, or CST registrations for each state.
- Input Tax Credit — you only pay tax on the value you add, which directly protects your margins.
- Easier logistics — no more state border check-posts; goods move faster and cheaper.
- Digital compliance — everything is on one portal. Once your books are in order, filing is straightforward.
- Level playing field — unorganised competitors who stay out of the tax net eventually lose because large buyers only deal with GST-registered vendors.
- Higher credibility — GSTIN on your invoices signals a real, formal business to clients and banks.
Five Common GST Mistakes Beginners Make
- Missing the mandatory registration rule for inter-state or e-commerce sales and waiting for the turnover threshold.
- Claiming Input Tax Credit without matching it to GSTR-2B — this is the single biggest cause of notices.
- Using wrong HSN/SAC codes on invoices, which creates mismatches with buyers’ returns.
- Skipping nil returns in months with no activity, then accumulating late fees.
- Opting for the Composition Scheme without checking if your buyers need proper tax invoices — you may lose B2B clients who want ITC.
How CleverCoins Can Help
GST is designed to be simple in principle, but the real world has deadlines, notices, classification arguments, and portal outages. At CleverCoins, we have been handling GST for businesses across the Mumbai Metropolitan Region for over five years.
Whether you need:
- Fresh GST registration for a new business
- Monthly or quarterly return filing (GSTR-1, GSTR-3B, GSTR-9)
- Composition Scheme advice and conversion
- Response to GST notices and assessments
- ITC reconciliation and HSN classification
…we can take it off your plate so you can focus on running your business. Visit clevercoins.org or message us directly — the first consultation is always free.