Reading a GST invoice, line by line

A GST invoice is not just a bill. It is the document that lets your customer claim back the GST they paid you, and that the tax department reads when your returns and theirs do not match. Read one line by line and each part has a job.

Who is selling, and who is buying

The seller's name, address and GSTIN — the 15-character GST number — are at the top. If the buyer is a registered business, their name, address and GSTIN are on it too. A business buyer will check this line first: if their GSTIN is missing or wrong, they cannot claim the tax back, and the invoice is useless to them.

The number and the date

Every invoice has its own serial number. Numbers run in order and are not reused, so a gap or a repeat is the first thing anyone checking your books will ask about.

What was sold

Each line has a description, quantity, unit and price — and an HSN code for goods, or SAC code for services. The code is how the tax system knows what the thing is, and the GST rate follows from it.

The tax, split one of two ways

This is the part people get wrong.

• Seller and place of supply in the same state: the tax is split in half, CGST (to the centre) and SGST (to the state). At 18%, that is 9% + 9%.
• Different states: it is all IGST, at the full rate, in one line.

The total is the same either way. What changes is which government gets it — so the wrong split means your customer's return will not match yours.

When there is no GST on it at all

A business registered under the composition scheme cannot charge GST. It issues a bill of supply instead of a tax invoice, and its customers cannot claim any tax back from it. If a supplier on composition hands you a "tax invoice" with GST on it, ask why.

Taxable value, total, and the amount in words

The taxable value is the price before tax. The invoice shows tax by rate, the grand total, and the total written out in words — in lakh and crore — so a figure cannot be quietly changed.