GST Invoicing Rules in India: Slabs, HSN Codes & Input Tax Credit (ITC) Explained
Complete guide for Indian businesses and freelancers on GST calculation, CGST vs SGST vs IGST, mandatory invoice fields, and claiming Input Tax Credit legally.
The Goods and Services Tax (GST) is India unified destination-based indirect tax system levied on the supply of goods and services. For ecommerce sellers, retail merchants, and independent service providers, correctly calculating GST and issuing compliant invoices is mandatory to ensure smooth operations and avoid tax penalties.
Understanding GST components: CGST, SGST, and IGST
- Intra-State Supply (Within the same State): The tax is equally split into Central GST (CGST) and State GST (SGST). For example, on an 18% tax item, 9% goes to CGST and 9% to SGST.
- Inter-State Supply (Between different States or UTs): Integrated GST (IGST) is charged at the full rate (e.g. 18%) and collected directly by the Central Government.
- UTGST: Union Territory GST applies in place of SGST for Union Territories without a legislature (e.g., Chandigarh, Ladakh).
GST tax rate slabs in India
Goods and services fall into five primary GST tax brackets:
- 10% (Exempt): Unpacked food grains, fresh vegetables, milk, curd, and essential educational services.
- 25%: Packaged staple foods, domestic air travel, life-saving medicines, and rail freight.
- 312%: Processed food products, standard hotel rooms, business software services, and medical equipment.
- 418% (Standard): Most consumer electronics, IT services, financial consulting, dining in air-conditioned restaurants, and capital goods.
- 528% (Luxury & Sin): Automobiles, tobacco, luxury motorcycles, carbonated drinks, and high-end consumer appliances.
How Input Tax Credit (ITC) works
Input Tax Credit is the cornerstone of GST, preventing the cascading effect of tax-on-tax. When you buy goods or business supplies for your enterprise, you pay GST to your vendor (Input Tax). When you sell your products or services to customers, you collect GST (Output Tax).
Net GST Payable = Output GST (Collected) - Input Tax Credit (Paid)
For instance, if you collect ₹18,000 GST on client billings and paid ₹10,000 GST on business laptop and server hosting purchases, your net payment to the government is only ₹8,000.
Mandatory fields for a valid GST tax invoice
- Supplier legal business name, registered address, and 15-digit GSTIN.
- Consecutive serial invoice number (unique for the financial year) and invoice date.
- Recipient name, address, and GSTIN (for B2B registered customers).
- Harmonized System of Nomenclature (HSN) code for goods or SAC code for services.
- Clear breakdown of taxable value, rate of tax, and separate columns for CGST, SGST, or IGST.
Frequently Asked Questions
Who is required to register for GST in India?
Businesses with annual turnover exceeding ₹40 Lakhs for goods (₹20 Lakhs for special category states) or ₹20 Lakhs for services must register. Mandatory registration also applies to ecommerce sellers regardless of turnover threshold.
What is the reverse charge mechanism (RCM)?
Under RCM, the recipient of goods or services is liable to pay GST directly to the government instead of the supplier, commonly applicable on goods transport agencies (GTA) and certain legal services.
Can a composition dealer claim Input Tax Credit?
No. Businesses registered under the GST Composition Scheme pay a flat lower tax rate on turnover but are not permitted to collect GST from customers or claim Input Tax Credit on purchases.
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