If you're running a business in India, GST is just... part of life now. Since 2017, it's simplified a lot of indirect tax headaches, but it also means one thing: **your invoice has to be right**. One wrong field and your client loses their ITC claim. That's not a conversation you want to have.

I've spent enough time dealing with accountants to know what actually matters. Let's break it down without the jargon.

## Tax Invoice or Bill of Supply?

Quick rule: If you're GST registered and selling taxable stuff to another registered business, you issue a **Tax Invoice**.

But if you're on the Composition Scheme or selling exempted goods (like fresh vegetables), you issue a **Bill of Supply** instead. No tax collection there.

## The Mandatory Fields (Checklist)

According to GST Rule 46, a tax invoice _must_ contain specific details to be valid. Missing even one can render the invoice invalid for ITC claims.

### Header Details

- Your Legal Name & Address
- Your GSTIN (15-digit ID)
- Consecutive Serial Number (unique)
- Date of Issue

### Recipient Details

- Recipient Name & Address
- Recipient GSTIN (if registered)
- Place of Supply (State Code)

## Understanding Tax Types: IGST, CGST, SGST

This is where most mistakes happen. The tax you charge depends entirely on the location of your customer relative to you.

- Intra-State: If you and the buyer are in the **same state** (e.g., Maharashtra to Maharashtra), you split the tax: 50% CGST (Central) + 50% SGST (State).
- Inter-State: If the buyer is in a **different state** (e.g., Delhi to Karnataka), you charge a single tax component: IGST (Integrated GST).

**Important Note on HSN/SAC Codes**

You must mention the Harmonized System of Nomenclature (HSN) code for goods or Service Accounting Code (SAC) for services. For businesses with turnover > ₹5 Cr, a 6-digit code is mandatory.

## The Bottom Line

GST invoicing looks complicated until you've done it a few times. Get a template that handles the IGST vs CGST/SGST logic automatically, and it becomes second nature.

Try our [GST Invoice Template](/content/in/gst-invoice/index.html) - it ensures you never miss a mandatory field, and the tax math is done for you. Also check out templates for [tax consultants](/content/in/tax-consultancy-invoice/index.html) and [travel agencies](/content/in/travel-agency-invoice/index.html).

#### India-Specific Templates

[GST Invoice Standard GST-compliant format](/content/in/gst-invoice/index.html) 
[Gym Invoice For fitness businesses](/content/in/gym-invoice/index.html) 
[Social Media For digital agencies](/content/in/social-media-invoice/index.html) 
[Advanced GST Guide E-invoicing, ITC, RCM explained](/content/blog/mastering-gst-compliance-2026/index.html)