What Is GST? Complete Guide to GST in India 2026

What Is GST?

GST — Goods and Services Tax — is India's comprehensive indirect tax that replaced multiple state and central taxes from 1 July 2017. Before GST, businesses paid VAT, service tax, central excise, entry tax, and various other taxes that varied by state and created complexity for businesses operating across states.

GST unified all of these into a single tax framework — "One Nation, One Tax."

GST is a multi-stage, destination-based consumption tax:

• Multi-stage: Tax is collected at every stage of the supply chain (manufacturer → distributor → retailer → consumer)
• Destination-based: Tax accrues to the state where the final consumption happens, not where the goods are manufactured

The key feature that makes GST different from cascading taxes: Input Tax Credit (ITC). Businesses can offset GST paid on purchases against GST collected on sales — only the net difference is paid to the government. This eliminates the tax-on-tax problem of the old system.

---

How GST Works: A Step-by-Step Example

A shirt that moves from cotton farmer → yarn maker → fabric manufacturer → garment maker → retailer → consumer:

Each business in the chain pays GST only on the value it adds, not on the full transaction value. The total GST is collected from the final consumer — businesses in the chain are collection agents, not final payers.

---

The Three Types of GST

India has a dual GST structure: central GST and state GST levied simultaneously:

CGST — Central Goods and Services Tax

Levied by the central government on intrastate (within the same state) supplies. Half the total GST rate.

SGST — State Goods and Services Tax

Levied by the state government on intrastate supplies. The other half of the total GST rate.

Example: An 18% GST on a product sold within Maharashtra = 9% CGST + 9% SGST. CGST goes to the central government; SGST goes to Maharashtra.

IGST — Integrated Goods and Services Tax

Levied on interstate supplies (across states) and imports. Equal to the full GST rate (CGST + SGST combined). IGST is collected centrally and then divided between central and destination state governments.

Example: 18% GST on a product sold from Maharashtra to Delhi = 18% IGST collected; IGST distributed between central government and Delhi.

On your invoice:

• Same-state customer: Show CGST + SGST
• Different-state customer: Show IGST only
• Exported goods: 0% (zero-rated; ITC is refundable)

---

GST Rate Structure

GST uses a tiered rate structure:

Finding the right GST rate: Use the HSN (Harmonised System of Nomenclature) code for goods or SAC (Service Accounting Code) for services. Search the CBIC GST rate finder at gst.gov.in for the correct rate and code for your specific product or service.

---

GST Registration

Who Must Register?

Mandatory registration:

• Annual aggregate turnover exceeds ₹40 lakh (for suppliers of goods in most states)
• Annual aggregate turnover exceeds ₹20 lakh (for suppliers of services, or goods suppliers in special category states)
• E-commerce sellers (Amazon, Flipkart, Meesho, Myntra) — mandatory regardless of turnover
• Interstate suppliers of goods or services
• Casual taxable persons
• Non-resident taxable persons
• Persons liable to pay under Reverse Charge Mechanism

Voluntary registration: You can register voluntarily even below the threshold. Benefits: claim input tax credit on purchases; B2B customers can claim ITC on purchases from you (making you more attractive as a supplier).

GST Registration Process

Visit gst.gov.in → New Registration

Part A: Enter PAN, mobile number, email — receive TRN (Temporary Reference Number)

Part B: Complete the application with business details, address proof, bank account, authorised signatory details

Upload documents: PAN card, Aadhaar, address proof, bank statement/cancelled cheque, photograph

Verification: GSTN sends verification code to registered mobile/email

ARN (Application Reference Number) generated: track application status

GSTIN issued: 15-digit number within 3–7 working days (7 working days for Aadhaar-authenticated applications)

The GSTIN format: 2 digits (state code) + 10 digits (PAN) + 2 digits (entity number) + 1 check digit. Example: 27AABCU9603R1ZX = Maharashtra, PAN AABCU9603R, first registered entity.

---

Input Tax Credit (ITC)

ITC is the mechanism that prevents tax-on-tax. GST paid on business purchases can be offset against GST collected on sales.

How ITC Works

You pay ₹18,000 GST on office equipment purchased for your business. This month you collect ₹50,000 GST from your customers. You pay to the government: ₹50,000 − ₹18,000 = ₹32,000.

ITC Eligibility Rules

You CAN claim ITC on:

• Raw materials and components used in manufacturing
• Capital goods used in business
• Services used in business (accounting, legal, IT)
• Goods purchased for resale

You CANNOT claim ITC on:

• Personal expenses
• Motor vehicles (except for certain businesses: taxi services, driving schools)
• Food and beverages (unless you are in the food service business)
• Club memberships
• Health insurance (with exceptions)
• Goods purchased under the Composition Scheme
• Goods used for exempt supplies

ITC Reconciliation (Critical)

From FY 2021–22, ITC can be claimed only if:

The supplier has uploaded the invoice in GSTR-1

The invoice appears in your GSTR-2B (auto-populated from supplier's GSTR-1)

You have actually received the goods/services

The supplier has paid GST

If a supplier files GSTR-1 late or incorrectly, your ITC may be blocked. This makes supplier compliance critical — work with suppliers who file GST returns on time.

---

GST Returns: What You Need to File

GSTR-1: Outward Supply Details

What it is: Details of all sales invoices issued during the period. Who files: Every GST-registered business. Frequency:

• Turnover above ₹5 crore: Monthly, due by 11th of the following month
• Turnover below ₹5 crore with QRMP scheme: Quarterly (Jan-Mar, Apr-Jun, Jul-Sep, Oct-Dec), due by 13th of the month after the quarter end
• Can opt for monthly filing even below ₹5 crore

What to include: Each invoice with customer GSTIN (for B2B), invoice number, date, value, tax amount. B2C invoices can be aggregated.

GSTR-3B: Summary Return and Tax Payment

What it is: Summary of outward and inward supplies + net tax payable. Frequency: Monthly for most businesses; quarterly for QRMP scheme businesses. Due date: 20th of the following month (with some variations by state and turnover). Tax payment: GST must be paid when filing GSTR-3B — no tax payment without filing.

GSTR-9: Annual Return

What it is: Reconciliation of all returns filed during the financial year. Who files: All businesses with turnover above ₹2 crore (mandatory); voluntary for below ₹2 crore. Due date: 31 December following the end of the financial year.

IFF — Invoice Furnishing Facility (QRMP Scheme)

Businesses on the QRMP scheme can optionally upload B2B invoice details for the first two months of each quarter via IFF — allowing their buyers to claim ITC without waiting for the quarterly GSTR-1.

---

E-Invoicing: Mandatory for Larger Businesses

E-invoicing in India does not mean sending invoices by email. It means generating invoices through the Government's Invoice Registration Portal (IRP) and getting an IRN (Invoice Reference Number) and QR code embedded in each invoice before issuing it to the customer.

Current threshold: Mandatory for businesses with annual aggregate turnover above ₹10 crore (as of October 2022).

How it works:

You create an invoice in your accounting/billing software

Software automatically submits invoice details to IRP via API

IRP validates, assigns an IRN (a unique 64-character hash), and returns the validated invoice with a signed QR code

You print and send the invoice to the customer — it is now a valid tax invoice

Key point: An invoice without an IRN (for businesses above the threshold) is invalid — your buyer cannot claim ITC on it, and you are liable for penalties.

Accounting software with e-invoicing integration (like [Taskmate ERP](/taskmate), Zoho Books, Tally Prime) handles this automatically — you create the invoice normally, and IRP submission happens in the background.

---

GST Composition Scheme

The Composition Scheme is a simplified GST compliance option for small businesses:

Eligibility:

• Aggregate annual turnover below ₹1.5 crore (goods) or ₹75 lakh (services, and composition scheme for services is limited to 50 lakh for certain service providers)

How it works:

• Pay a flat rate on turnover (1% for traders/manufacturers, 5% for restaurants, 6% for service providers)
• File quarterly return (CMP-08) and annual return (GSTR-4)
• No ITC on purchases
• Cannot make interstate supply of goods
• Must display "Composition Taxable Person, Not Eligible to Collect Tax on Supplies" on all invoices

Who should choose Composition Scheme: Businesses that sell primarily to end consumers (B2C) with simple operations and limited interstate activity. The simplicity benefit (flat tax, simple quarterly filing) is significant. The ITC loss is the main disadvantage — businesses with significant input purchases lose this benefit.

---

Frequently Asked Questions

What is GST registration and is it mandatory? GST registration is the process of getting a GSTIN from the government, which authorises you to collect GST on sales and claim ITC on purchases. It is mandatory if your annual turnover exceeds ₹40 lakh (goods) or ₹20 lakh (services). For e-commerce sellers, registration is mandatory regardless of turnover. Voluntary registration below the threshold is possible and beneficial if your B2B customers need to claim ITC.

What is the difference between CGST, SGST, and IGST? CGST and SGST are levied simultaneously on intrastate (within-state) transactions — CGST goes to the central government, SGST to the state government. IGST is levied on interstate transactions and imports — it replaces both CGST and SGST for cross-state supplies. As a seller, if you sell within your state, charge CGST + SGST. If you sell to a customer in another state, charge IGST. The total rate is the same.

What is input tax credit in GST? Input Tax Credit allows businesses to offset GST paid on purchases against GST collected on sales. Only the net amount is paid to the government. Example: you collect ₹30,000 GST on sales and paid ₹12,000 GST on purchases — you pay ₹18,000 net to the government. ITC prevents the cascading effect of taxes on taxes.

Who is exempt from GST? Businesses below the registration threshold (₹40 lakh for goods, ₹20 lakh for services) are not required to register and therefore do not charge or collect GST. Certain goods and services are exempt from GST regardless of the supplier's size: fresh agricultural produce, healthcare, education, and others listed under the GST exemption schedule.

What happens if I don't file GST returns on time? Late filing attracts a late fee: ₹50/day (₹25 CGST + ₹25 SGST) for GSTR-1 and GSTR-3B; ₹20/day for nil returns. Interest at 18% per annum applies on unpaid tax. Repeated non-filing can result in cancellation of GST registration and initiation of assessment proceedings. File on time — the late fee accumulates quickly for frequent filers.

What is the GST e-invoicing limit? Currently, e-invoicing (generating invoices through the IRP with an IRN) is mandatory for businesses with aggregate annual turnover above ₹10 crore. This threshold has been progressively lowered — it started at ₹100 crore in October 2020, reduced to ₹50 crore, then ₹20 crore, then ₹10 crore. Expect further reduction over time. Businesses below the threshold can voluntarily use e-invoicing.

---

Read more about [GST billing software India 2026](/blog/gst-billing-software-india-2026), [small business tax guide 2026](/blog/small-business-tax-guide-2026), or [small business accounting basics guide](/blog/small-business-accounting-basics-guide).