How to Add GST to an Invoice in India

To add GST to an invoice in India, you issue a GST tax invoice that shows your GSTIN and the customer's GSTIN, applies the correct GST rate to the taxable value, and splits the tax correctly: CGST plus SGST for a sale within your state, or IGST for a sale to another state. The total the customer pays is the taxable value plus the GST. The split between CGST, SGST, and IGST is the part that is unique to India and the part people most often get wrong.

GST replaced a tangle of older indirect taxes in India with a single system, but a compliant invoice still has specific requirements. Get the GSTIN, the place of supply, the tax split, and the required fields right, and your invoice is valid and your customer can claim their input tax credit.

When you need to register and charge GST

GST registration is required once your turnover crosses the applicable threshold, and it is also required in certain situations regardless of turnover, such as inter-state supply of goods in some cases. The turnover thresholds differ for goods and services and for certain special category states.

As a general guide, the threshold for services has commonly been 20 lakh rupees, with a lower 10 lakh figure for some special category states, while the threshold for goods has commonly been 40 lakh. These figures and the rules around them can change, so confirm the current thresholds for your situation before relying on them. Once registered, you receive a GSTIN, a 15-character identifier that must appear on your invoices.

If you are not registered, you do not charge GST and you cannot issue a GST tax invoice. The rest of this article assumes you are registered.

The CGST, SGST, and IGST split

This is the heart of GST invoicing. Which taxes you apply depends on the place of supply relative to your own location.

For an intra-state supply, where the customer is in the same state as you, the GST is split into two equal halves: Central GST (CGST) and State GST (SGST). If the total GST rate is 18 percent, you charge 9 percent CGST and 9 percent SGST.

For an inter-state supply, where the customer is in a different state, you charge a single Integrated GST (IGST) at the full rate. So 18 percent becomes 18 percent IGST, with no CGST or SGST.

The total tax is the same either way. What changes is how it is split and labelled, which determines how the revenue is shared between the central and state governments. Determining the place of supply correctly is therefore essential, because it decides which taxes appear on your invoice.

What a GST tax invoice must contain

A GST-compliant tax invoice has a defined set of required fields. Missing them can make the invoice non-compliant and can stop your customer claiming input tax credit.

The invoice should show your name, address, and GSTIN; a consecutive invoice number unique for the financial year; the date of issue; the customer's name, address, and GSTIN if they are registered; the HSN code for goods or the SAC code for services; a description of the goods or services; the quantity and taxable value; the GST rate and the amount of CGST, SGST, or IGST as applicable; the place of supply; and the total. For an inter-state supply, the place of supply and the state are particularly important.

The requirement for a consecutive, unique invoice number is strict in India, so a clean numbering system matters. The general principles of good numbering are in how to number your invoices, and the broader checklist of invoice fields is in what to put on an invoice.

GST rates and the taxable value

GST in India is charged at different rate slabs depending on the goods or services, with common slabs including 5, 12, 18, and 28 percent, and some items zero-rated or exempt. You apply the rate that matches what you are supplying.

The tax is calculated on the taxable value, which is generally your price for the supply. So a service with a taxable value of 10,000 at 18 percent carries 1,800 of GST, shown as 900 CGST plus 900 SGST within the state, or 1,800 IGST across states, for a total of 11,800. The arithmetic of adding a percentage to a base is the same as any tax, and the VAT calculator can help you check the add-on amounts even though it is labelled for VAT, since the percentage maths is identical. The presentation principles also mirror how to add VAT to an invoice.

Confirm the current rules

GST rules, rates, thresholds, and filing requirements in India are detailed and subject to change, and there are additional considerations such as e-invoicing requirements for businesses above certain turnover levels, reverse charge in specific cases, and return filing. This article gives you the structure of a compliant invoice, but the precise rates, thresholds, and obligations for your business should be confirmed against current GST rules or with a chartered accountant.

What stays constant is the shape: register and get a GSTIN, determine the place of supply, split into CGST and SGST within the state or charge IGST across states, and include all the required fields. When you build the document, the free invoice generator lets you lay out a clean invoice with your GSTIN, the tax breakdown, and the customer details, running in your browser with no signup and nothing stored on a server.

Common questions

When do I charge CGST and SGST versus IGST?

It depends on the place of supply. For an intra-state supply, where the customer is in the same state as you, the GST is split into two equal halves, CGST and SGST. For an inter-state supply, where the customer is in a different state, you charge a single IGST at the full rate. The total tax is the same either way. What changes is how it is split and labelled, which determines how the revenue is shared between central and state governments.

What must a GST tax invoice contain?

It should show your name, address, and GSTIN; a consecutive invoice number unique for the financial year; the date; the customer's name, address, and GSTIN if they are registered; the HSN code for goods or SAC code for services; a description, quantity, and taxable value; the GST rate and the amount of CGST, SGST, or IGST as applicable; and the place of supply. Missing these can make the invoice non-compliant and stop your customer claiming input tax credit.

Do I need to register for GST?

You must register once your turnover crosses the applicable threshold, and in certain situations regardless of turnover. As a general guide, the threshold for services has commonly been 20 lakh rupees, with a lower 10 lakh figure for some special category states, while the threshold for goods has commonly been 40 lakh. These figures can change, so confirm the current thresholds for your situation. Once registered, you receive a 15-character GSTIN that must appear on your invoices.

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