GST (Goods and Services Tax) replaced over a dozen central and state taxes in India when it launched on July 1, 2017. Today, GST affects every business transaction, every invoice, and every shopping receipt in the country.
Whether you're a business owner calculating invoices, a consumer trying to understand what you're paying, or a student learning taxation — this guide explains GST from the ground up.
What Is GST?
GST is a unified indirect tax applied to the supply of goods and services in India. It replaced taxes like:
- Central Excise Duty
- Service Tax
- VAT (Value Added Tax)
- Central Sales Tax
- Octroi
The core concept: tax is collected at every stage of the supply chain, but only on the value added at each stage. The final consumer bears the full tax burden.
The Three Components of GST
When a transaction happens within a state (intra-state), GST is split into two:
- CGST (Central GST) — goes to the Central Government
- SGST (State GST) — goes to the State Government
Each is typically half the total GST rate.
When a transaction happens across states (inter-state):
- IGST (Integrated GST) — goes to the Central Government (then shared with destination state)
Example:
- Selling a product in Maharashtra to a buyer also in Maharashtra: Charge CGST 9% + SGST 9% = 18% total
- Selling from Maharashtra to Delhi: Charge IGST 18% (no split)
GST Rate Slabs in India (2026)
| Slab | What It Covers |
|---|---|
| 0% | Essential goods: rice, wheat, fresh vegetables, milk, eggs, books, newspapers, healthcare services, educational services |
| 5% | Packaged food, household necessities, transport services, economy class airfare |
| 12% | Computers, processed food, business class flights, some medicines |
| 18% | Most goods and services: electronics, telecom, insurance, restaurants, most B2B services, IT software |
| 28% | Luxury and demerit goods: cigarettes, aerated drinks, luxury cars, casinos, online gaming |
Note: Some items have special composition rates, cess, or exemptions. This table is a general overview.
How to Calculate GST: The Formula
Adding GST to a Price (Exclusive of GST)
This applies when a seller quotes a base price and GST is added on top.
GST Amount = Base Price × (GST Rate / 100) Total Price = Base Price + GST Amount = Base Price × (1 + GST Rate/100)
Example: An IT service provider charges ₹50,000 for a service with 18% GST.
- GST = ₹50,000 × 18/100 = ₹9,000
- Total invoice = ₹50,000 + ₹9,000 = ₹59,000
- CGST (9%) = ₹4,500
- SGST (9%) = ₹4,500 (if within same state)
Removing GST from a Price (Inclusive of GST)
When you know the final price including GST and need to extract the base price.
Base Price = Total Price / (1 + GST Rate/100) GST Amount = Total Price − Base Price
Example: A smartphone is priced at ₹17,700 inclusive of 18% GST.
- Base price = ₹17,700 / 1.18 = ₹15,000
- GST amount = ₹17,700 − ₹15,000 = ₹2,700
Worked Examples Across GST Slabs
Example 1: Restaurant Bill (18% GST)
- Food ordered: ₹800
- GST @ 18%: ₹144
- Total bill: ₹944
- CGST (9%) = ₹72 | SGST (9%) = ₹72
Example 2: Packaged Atta (5% GST)
- Packet MRP inclusive of GST: ₹210
- Base price = ₹210 / 1.05 = ₹200
- GST = ₹10
Example 3: Mobile Phone (18% GST)
- Base price = ₹25,000
- GST (18%) = ₹4,500
- Final price = ₹29,500
Example 4: Luxury Car (28% GST + Cess)
- Base price = ₹15,00,000
- GST (28%) = ₹4,20,000
- Cess (22% on luxury cars) = ₹3,30,000
- Total price = ₹22,50,000
Input Tax Credit (ITC): How Businesses Avoid Double Taxation
The most important concept in GST for businesses is Input Tax Credit (ITC).
When a business pays GST on its purchases (inputs), it can deduct this from the GST it collects on its sales (output). This prevents cascading — the "tax on tax" problem that existed before GST.
Example: A furniture manufacturer
| Stage | Actor | Selling Price | GST (18%) | GST Paid | ITC Claimed | Net GST to Govt |
|---|---|---|---|---|---|---|
| Raw material | Sawmill | ₹10,000 | ₹1,800 | ₹1,800 | — | ₹1,800 |
| Processing | Manufacturer | ₹25,000 | ₹4,500 | ₹4,500 | ₹1,800 | ₹2,700 |
| Retail | Shop | ₹40,000 | ₹7,200 | ₹7,200 | ₹4,500 | ₹2,700 |
| Final Consumer | Buyer | ₹40,000 | — | ₹7,200 | — | — |
Total GST collected by government = ₹1,800 + ₹2,700 + ₹2,700 = ₹7,200 — exactly 18% of the final consumer price. No double taxation.
Who Needs GST Registration?
Mandatory Registration
You must register for GST if:
- Annual turnover exceeds ₹40 lakh (goods in most states) or ₹20 lakh (services/northeastern states)
- You sell inter-state (regardless of turnover)
- You're an e-commerce seller (no threshold)
- You're a foreign taxpayer
- You receive reverse charge mechanism transactions
Voluntary Registration
Businesses below the threshold can voluntarily register to:
- Claim ITC on purchases
- Supply to GST-registered businesses who need ITC
- Appear more legitimate to corporate buyers
GST Composition Scheme
For small businesses with turnover between ₹10 lakh and ₹1.5 crore, the Composition Scheme offers simplified compliance:
| Business Type | Rate on Turnover |
|---|---|
| Manufacturers | 1% |
| Traders | 1% |
| Restaurants (not serving alcohol) | 5% |
| Service providers | 6% |
Advantages: Simple quarterly return, lower tax rate Disadvantages: Cannot claim ITC, cannot charge GST on invoices to buyers, cannot sell inter-state
GST on Services You Use Every Day
| Service | GST Rate |
|---|---|
| Restaurant (non-AC) | 5% |
| Restaurant (AC or liquor license) | 18% |
| Hotels (tariff below ₹2,500) | 12% |
| Hotels (tariff above ₹7,500) | 18% |
| Air travel (economy) | 5% |
| Air travel (business class) | 12% |
| Mobile/internet services | 18% |
| Insurance premium | 18% |
| Movie tickets (above ₹100) | 18% |
| Real estate (under construction) | 5% (no ITC) |
| Education | 0% (exempt) |
| Healthcare | 0% (exempt) |
GST Compliance: What Businesses Need to Do
Return Filing
| Return | Who Files | Frequency |
|---|---|---|
| GSTR-1 | All regular taxpayers | Monthly (or quarterly if turnover < ₹5Cr) |
| GSTR-3B | All regular taxpayers | Monthly |
| GSTR-9 | Annual return | Yearly |
| GSTR-4 | Composition scheme taxpayers | Yearly |
ITC Conditions
To claim Input Tax Credit, the business must ensure:
- Tax invoice or debit note received
- The goods/services were received
- Supplier has filed returns and paid the tax
- ITC matches in GSTR-2B (auto-populated reconciliation)
E-Commerce and GST
Online sellers on Amazon, Flipkart, Meesho, etc. have specific GST obligations:
- Mandatory registration regardless of turnover (no threshold exemption)
- TCS (Tax Collected at Source): E-commerce operators collect 1% GST from sellers and pay to government
- Multiple state registrations needed if selling across states
Frequently Asked Questions
Does GST apply to exports?
No. Exports are zero-rated under GST. The exporter charges 0% GST and can claim refund of GST paid on inputs used for export.
What is a GST invoice?
A legal document issued by a registered seller containing: GSTIN of buyer and seller, description of goods/services, HSN/SAC code, taxable value, GST rate, and GST amount (CGST, SGST, or IGST).
What is GSTIN?
GST Identification Number — a 15-digit unique number assigned to every GST-registered business. Format: 2-digit state code + 10-digit PAN + entity code + check digit.
Can an individual claim GST refund?
Individuals cannot claim GST refunds (no ITC for consumers). Businesses claim ITC to reduce their GST liability.
What happens if I don't pay GST?
Penalties range from ₹10,000 to the full amount of tax evaded, plus interest at 18–24% per annum. Deliberate fraud can result in prosecution.
What is the difference between inclusive and exclusive GST?
Inclusive GST: the listed price already includes GST. To extract base price: Price ÷ (1 + rate/100). Exclusive GST: GST is added to the listed price. Total = Price × (1 + rate/100).
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