Educational Knowledge Module

GST Student Guide — GST Explained in Simple Words

Designed specifically for commerce students, finance beginners, and taxpayers. Master CGST, SGST, IGST, Input Tax Credit (ITC), and invoice calculations step-by-step.

GST Student Guide Accounting Illustration

Student Learning Roadmap

1 What is GST? 2 CGST vs SGST vs IGST 3 Input Tax Credit (ITC) 4 15-Digit GSTIN Code 5 Composition Scheme 6 Reverse Charge (RCM) 7 Solved Calculation Examples 8 Interactive Practice Quiz

What is Goods & Services Tax (GST)?

Goods & Services Tax (GST) is a comprehensive, multi-stage, destination-based indirect tax levied on every value addition in India. It came into effect on July 1, 2017, through the 101st Constitutional Amendment Act, subsuming over 17 previous indirect taxes such as Excise Duty, Service Tax, VAT, Octroi, and Entry Tax under the motto "One Nation, One Tax, One Market".

Comprehensive Tax

Combines central and state indirect taxes into a single unified tax structure across India.

Multi-Stage Tax

Levied at every point in the supply chain from raw material purchase to final retail sale.

Destination-Based

Tax revenue belongs to the consuming state where goods/services are finally consumed.

Types of GST: CGST, SGST, IGST & UTGST Explained

India follows a Dual GST model where both the Central Government and State Governments simultaneously levy taxes on transactions.

Intra-State Supply Same State

When supplier and buyer are located within the SAME state (e.g. Mumbai seller selling to Pune buyer in Maharashtra):

CGST (Central GST): 50% of GST Rate

SGST (State GST): 50% of GST Rate

Inter-State Supply Different States

When supplier and buyer are located in DIFFERENT states (e.g. Delhi seller selling to Bengaluru buyer in Karnataka):

IGST (Integrated GST): 100% of GST Rate

Collected by Centre and transferred to the consuming state.

Input Tax Credit (ITC) & Eliminating Tax Cascading

Before GST, businesses paid tax on tax (cascading effect). Input Tax Credit (ITC) allows a seller to deduct the tax already paid on purchases (Input Tax) from the tax collected on sales (Output Tax).

Step-by-Step Supply Chain Numerical Example (18% GST Rate)

Stage 1: Manufacturer

Cost: ₹10,000

Output GST (18%): ₹1,800

ITC Claimed: ₹0

Net Tax Paid to Gov: ₹1,800

Stage 2: Wholesaler

Purchases at: ₹10,000 + Value Add ₹5,000 = ₹15,000

Output GST (18%): ₹2,700

Input Tax Paid earlier: ₹1,800 (ITC)

Net Tax Paid to Gov: ₹900

Stage 3: Retailer

Purchases at: ₹15,000 + Value Add ₹5,000 = ₹20,000

Output GST (18%): ₹3,600

Input Tax Paid earlier: ₹2,700 (ITC)

Net Tax Paid to Gov: ₹900

Total Tax Collected by Government = ₹1,800 + ₹900 + ₹900 = ₹3,600 (Exactly 18% of Final Consumer Price ₹20,000).

Structure of 15-Digit GST Identification Number (GSTIN)

Every registered taxpayer in India is assigned a unique 15-character alphanumeric GSTIN.

Example GSTIN Code Breakdown:

27AAAAA0000A1Z5

First 2 Digits: 2-Digit State Code (e.g. 27 for Maharashtra, 07 for Delhi)

Next 10 Digits: Business Owner / Entity PAN Number

13th Digit: Entity Registration Count in State (1-9, A-Z)

14th Digit: Default alphabet 'Z'

15th Digit: Checkcode digit for validation

Student Solved Calculation Examples

Example 1: Exclusive GST (Add 18% GST)

Problem: A computer technician charges ₹8,000 base fee for repair service within the same state. Compute total invoice amount.

Base Price = ₹8,000

CGST (9%) = ₹8,000 × 0.09 = ₹720

SGST (9%) = ₹8,000 × 0.09 = ₹720

Total Bill = ₹8,000 + ₹720 + ₹720 = ₹9,440.00

Example 2: Inclusive GST (Extract Net Amount from Total)

Problem: A customer buys a mobile charger for ₹1,180 total inclusive of 18% GST. What is the original net price before tax?

Formula: Net Amount = Total Amount × (100 / 118)

Net Base = ₹1,180 × (100 / 118) = ₹1,000.00

Extracted GST Tax = ₹1,180 - ₹1,000 = ₹180.00

Interactive Student Self-Assessment

Test Your GST Knowledge

Q1: Which GST type is levied on Inter-State sales between Delhi and Punjab?

Q2: What is the primary purpose of Input Tax Credit (ITC)?