GST invoicing for online orders: what your store must generate

What a GST invoice must contain

A compliant tax invoice isn't just a receipt. It must carry specific fields: your GSTIN, a unique invoice number, the date, the buyer's details, an HSN code for each item, the taxable value, the tax rate, and the tax split. Miss any of these and the invoice isn't valid for GST. Here's each part in plain terms.

The full Rule 46 checklist

Your GSTIN and a proper number series

Every invoice shows your GSTIN - your GST registration number. It also needs a unique serial number from a continuous series. You can't repeat numbers or skip around. Most stores number invoices automatically, which keeps the series clean and audit-proof without you tracking it by hand.

Buyers without a GSTIN

Most of your buyers are shoppers, not businesses, and the rule is lighter for them. For a buyer with no GSTIN, you must show their name, the delivery address and their state when the taxable value is ₹50,000 or more. Below ₹50,000, you add those details only if the buyer asks for them. For a business buyer, it is different. You show their name, address and GSTIN on every invoice, whatever the value. So ask for the GSTIN at checkout, before the order ships, not after.

The HSN code for every item

Each product needs its HSN code - the code that classifies goods for GST. It sets the tax rate, and it's mandatory on the invoice. How many digits you show depends on your turnover. Get the HSN right and the tax rate follows. Get it wrong and the whole invoice is off.

How many HSN digits to print

The digit count comes from Notification 78/2020, in force since 1 April 2021. It looks at your turnover in the last financial year. Up to ₹5 crore, you print a 4-digit HSN code. Above ₹5 crore, you print 6 digits. Smaller sellers also get one break. On sales to buyers without a GSTIN, they may leave the code off the invoice. Invoices to business buyers still need it.

The right tax rate

GST applies in slabs - commonly 0, 5, and 18 percent, with higher slabs for some goods. Each product sits in a slab set by its HSN. Apply the correct rate to the taxable value. If your catalogue mixes slabs, every line can carry a different rate - exactly the kind of thing you don't want to compute by hand.

CGST + SGST, or IGST - the split that trips people up

This is the part sellers get wrong most. For a sale within your state, GST splits into CGST and SGST, half each. For a sale to another state, it's a single IGST at the full rate. The buyer's state versus yours decides which. Your invoice must show the right split, not just the total.

When to raise the invoice

For goods, the law sets the timing. Section 31 of the CGST Act says you issue the tax invoice before or at the time you remove the goods for delivery. For an online order, that means when the parcel leaves you, not when the buyer pays. There is one small exception. For a sale under ₹200 to a buyer with no GSTIN who does not want an invoice, you may skip the single invoice. You then issue one invoice for all such sales at the close of each day.

E-invoicing once you cross ₹5 crore

E-invoicing is an extra step for bigger sellers. It began in October 2020 for firms with a turnover above ₹100 crore, and the limit has come down since. From 1 August 2023, it applies once your turnover in a financial year crosses ₹5 crore. It covers invoices to registered buyers, so your B2B sales. You upload the invoice details to the GST portal and get an Invoice Reference Number back. An invoice that skips this step when it should not is not treated as an invoice at all.

How many copies to keep

The rules also say how many copies to make. For goods, you prepare the invoice in three copies. The original is marked for the buyer, the duplicate for the transporter, and the triplicate for you. For services, you make two. An e-invoice follows its own process instead. Each tax period, you also report the serial numbers of the invoices you issued in GSTR-1. So a gap or a repeat in your series shows up there.

Credit notes for returns

When you refund or return an order, you issue a credit note - a matching document that reverses the tax. It links back to the original invoice. Skip it and your books and your GST returns fall out of step. Treat the credit note as part of the return, not an afterthought.

What a credit note can cover

Section 34 of the CGST Act lists when you can issue a credit note. It covers goods the buyer sends back, an invoice that charged too much, and goods found to be faulty. One credit note can cover several invoices from the same financial year. You report it in your return for the month you issue it, and your tax is adjusted. There is one catch. You cannot cut your tax this way if you have already passed that tax on to someone else.

Check an invoice before it goes out

1. Confirm your GSTIN and the invoice number are on it.
2. Check the number follows your series with no gap.
3. Check each line has the right HSN digits for your turnover.
4. Match the buyer's state to the CGST and SGST or IGST split.
5. Add the buyer's GSTIN for a business order.
6. Show the place of supply for a sale to another state.

Let the store do the math

Getting every field, rate, and split right on every order by hand is a month-end nightmare. The Storemate applies GST at checkout and generates a compliant invoice - with HSN, the correct slab, and the right CGST/SGST or IGST split - automatically, per order. A business buyer can add their GSTIN at checkout, the invoice is dated the day the order ships, and a refund on a shipped order raises a credit note. This is a starting point, not tax advice; for anything unusual, ask a qualified professional.