What is a proforma invoice?

A proforma invoice is a document you send to a customer before a sale is confirmed, showing what you propose to supply, the quantities, the prices and the estimated tax. It is essentially a detailed quotation in invoice form. It is not a demand for payment of tax and it does not record an actual sale, so it does not go into your GST returns. Customers often use it to arrange funds, get an approval, or place a purchase order before the real transaction happens.

What is a tax invoice?

A tax invoice is the official document that records an actual sale of goods or services and the GST charged on it. Under GST rules a registered business must issue a tax invoice for a taxable supply, and it must carry specific details such as your GSTIN, the invoice number and date, the customer details, the HSN or SAC codes, the taxable value, and the CGST, SGST or IGST amounts. It is the document that goes into your returns and lets the buyer claim input tax credit.

What is the main difference between the two?

Timing and legal effect. A proforma invoice comes before the sale is confirmed and is only a proposal, so it creates no tax liability and does not enter your books. A tax invoice comes when the sale actually happens and is the official record of that supply and its GST, so it enters your returns and supports the buyer's input tax credit. Put simply, a proforma says what a sale would look like, while a tax invoice records that the sale took place.

Can a customer pay against a proforma invoice?

Yes, customers often pay an advance or the full amount against a proforma invoice, because it tells them exactly what they are being asked to pay. However, the proforma is not the final tax document. Once the sale is confirmed and you supply the goods or service, you must issue a proper tax invoice for the transaction. The proforma helps the customer arrange the money and approve the purchase, and the tax invoice makes the sale official for GST.

Do I need software to handle both?

You do not strictly need it, but good billing software makes it far easier and less error-prone. It lets you create a proforma invoice as a proposal, then convert it into a proper GST tax invoice once the sale is confirmed, without retyping everything. This keeps the numbers consistent, applies the correct GST and HSN codes, and makes sure only real sales, not proformas, go into your records. It removes the common mistake of treating a proposal as an actual sale.

Proforma Invoice vs Tax Invoice: What Is the Difference

Two documents cause more confusion in Indian billing than almost any other: the proforma invoice and the tax invoice. They look similar, they both list items and prices, and both often carry the word invoice, yet they do very different jobs. Mixing them up leads to real problems, from booking a sale that has not happened to claiming or allowing tax credit on the wrong document. This guide explains clearly what each one is, when to send which, why a proforma is not a tax demand, what a GST tax invoice must contain, and how the two fit together in a clean billing flow.

What a proforma invoice is

A proforma invoice is a document you send before a sale is confirmed. Think of it as a detailed quotation dressed up in invoice form. It sets out what you propose to supply, the quantities, the prices and the estimated tax, so the customer can see exactly what the deal would cost. What it is not is just as important:

Not a record of a sale: nothing has been supplied yet, so a proforma does not enter your books or your GST returns.
Not a demand for tax: the tax shown is an estimate of what would apply, not a tax you are collecting on a completed sale.
Not final: quantities and prices can still change before the deal is confirmed.
A proposal: its job is to help the customer arrange funds, get an internal approval, or raise a purchase order.

In short, a proforma invoice describes a sale that might happen, so the customer can decide and prepare.

What a tax invoice is

A tax invoice is the official document that records a sale that has actually happened, along with the GST charged on it. Under GST rules, a registered business must issue a tax invoice for a taxable supply of goods or services. Unlike the proforma, it has legal weight: it enters your returns, it fixes your tax liability on that sale, and it lets the buyer claim input tax credit for the GST they paid. Because of that, it must carry a set of specific details, and getting those right is what makes it a valid tax invoice rather than just a bill. It is the document that says, plainly, that this sale took place and this much tax was charged.

The core difference

Strip away the surface similarity and the difference comes down to two things: timing and legal effect. A proforma comes before the sale is confirmed and carries no legal or tax weight, while a tax invoice comes when the sale happens and is the official record of it. Seeing them side by side makes it clear:

Hold on to one line from this table and you will rarely go wrong: a proforma says what a sale would look like, a tax invoice records that the sale took place.

When to send which

Once you see the difference, the timing follows naturally. Each document has its moment in the sale:

Send a proforma when a customer wants to know the exact cost before committing, needs a document to arrange funds, or has to get an approval or raise a purchase order.
Send a tax invoice when the sale is confirmed and you supply the goods or service, because that is the point the transaction becomes real and GST applies.

A common flow ties them together neatly. You send a proforma, the customer approves it and often pays an advance against it, you supply the goods or service, and then you issue the tax invoice that makes the sale official. The proforma helped the customer decide and pay, and the tax invoice records what actually happened.

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What a GST tax invoice must contain

Because a tax invoice carries legal and tax weight, it has to include specific details to be valid. The exact requirements are set by the GST rules, but in general a proper tax invoice should show:

Your details and GSTIN: your business name, address and GST registration number.
Invoice number and date: a unique serial number and the date of issue.
Customer details: the buyer's name and address, and their GSTIN if they are registered.
Item description with HSN or SAC: what is being supplied, along with the HSN code for goods or SAC code for services.
Taxable value: the value of the supply before tax, after any discount.
GST breakup: the CGST and SGST, or IGST for inter-state supply, shown separately with the rates.
Total amount: the final payable amount including tax.

Getting these right is what lets the buyer claim input tax credit and keeps you compliant. Billing software that knows the GST rules fills most of this in for you, which is why a proper tool beats a hand-typed bill. For more on that side, see our guide to GST billing software.

Common mistakes to avoid

A few errors around these two documents catch out small businesses, and each is easy to avoid once you know it:

Treating a proforma as a sale: booking a proforma in your records inflates your sales and can mess up your GST returns, because no supply has happened.
Never issuing the tax invoice: taking payment on a proforma and forgetting to raise the actual tax invoice leaves the real sale unrecorded and the buyer unable to claim credit.
Missing details on the tax invoice: a tax invoice without the GSTIN, HSN codes or a proper number may not be valid, which can cost the buyer their input credit.
Reusing invoice numbers: tax invoice numbers must be unique and in sequence, so a duplicated or out-of-order number causes problems at filing.

How software keeps the two in step

Handling proforma and tax invoices by hand is where mistakes creep in, because it is easy to retype figures wrong or to lose track of which document is which. Good billing software removes that risk. You create a proforma as a proposal, and once the sale is confirmed you convert it into a proper GST tax invoice in a tap, without retyping a thing. The numbers stay consistent from quote to final bill, the correct GST and HSN codes are applied, and crucially only real sales, the tax invoices, go into your records, while proformas stay out of them. This keeps your books clean and your returns accurate, and it spares you the most common error of all, which is treating a proposal as a completed sale.

The bottom line

A proforma invoice and a tax invoice are not two versions of the same thing. A proforma is a proposal you send before a sale, carrying no tax weight and staying out of your books, while a tax invoice is the official record of a sale that actually happened, carrying the GST and entering your returns. Send a proforma to help a customer decide and pay, and a tax invoice to make the sale official. IndiaCRM lets you raise a proforma, convert it into a compliant GST tax invoice, and keep your records clean, all in one free app. Read about GST billing software, see the pricing, or get the mobile app and send your first invoice today.