Proforma Invoice vs Tax Invoice: What's the Difference?

What a proforma invoice is (and is not)

A proforma invoice is a preliminary bill: a document that shows what a final invoice will look like, issued before the goods are shipped or the work is completed. "Pro forma" is Latin for "for the sake of form" — it has the form of an invoice, but it is not a demand for payment and it is not a record of a completed sale. Prices, quantities and dates on a proforma are commitments of intent, and the final figures can still change.

Because nothing has been sold yet, a proforma invoice does not enter your sales ledger, does not create a tax liability, and cannot be used by your customer to reclaim VAT or GST. It should be clearly labelled "Proforma Invoice" — that label is what prevents it being mistaken for the real thing by a customs officer, a bank or an accounts department.

What a tax invoice is

A tax invoice (called a VAT invoice in the UK and EU, a GST invoice in Pakistan, India, Australia and elsewhere, and simply a commercial invoice with tax details in some other systems) is the legal document of an actual sale. It is issued when goods or services have been supplied, it records the tax charged on that supply, and it is the evidence both sides use in their tax filings: the seller declares the output tax, and the buyer uses the document to reclaim input tax.

That legal status comes with requirements. A valid tax invoice typically must show the seller’s tax registration number, a unique sequential invoice number, the date of supply, the tax rate applied and the tax amount — the exact list varies by country, but missing elements can make the document invalid for reclaim purposes. It belongs in your accounts from the day it is issued, whether or not the client has paid yet.

Side by side: the practical differences

The two documents deliberately share a layout — that is the point of the proforma, to preview the real invoice — but almost everything about their status differs.

• Purpose — proforma: quote/confirm an upcoming sale. Tax invoice: record a completed sale and demand payment.
• When issued — proforma: before delivery. Tax invoice: at or after delivery.
• Tax — proforma: shows expected tax for information only; no tax is due. Tax invoice: the tax shown is legally charged and must be declared.
• Tax reclaim — proforma: the buyer cannot reclaim any tax from it. Tax invoice: the buyer’s evidence for reclaiming input tax.
• Bookkeeping — proforma: stays out of the sales ledger. Tax invoice: recorded as revenue and a receivable.
• Numbering — proforma: often a separate series or marked "PRO". Tax invoice: your main sequential series.

When to send a proforma

Send a proforma when the other side needs the full invoice picture before anything moves. The classic cases: a customer who must pay (or arrange payment) before you ship; customs and freight forwarders, who need values and descriptions for goods in transit; a bank processing a letter of credit or an advance payment; a client whose internal process requires an invoice-shaped document to raise a purchase order or release a deposit; and export orders generally, where the proforma doubles as the seller’s formal offer.

In services, the equivalent moment is the deposit invoice that is not yet a sale: a wedding venue confirming a booking, a developer starting on a 30% advance. If the money is an advance against future work rather than payment for work done, many businesses issue a proforma first and the tax invoice when the advance is applied or the work delivered — the exact treatment depends on your local rules for advance payments, which are worth one conversation with your accountant.

When only a tax invoice will do

Once the goods have been delivered or the work completed, the document must be a tax invoice. Your client cannot reclaim their input tax from anything else, their auditors will ask for it by name, and your own tax return is built from these documents. Sending a proforma at this stage does not just look unprofessional — it can leave the client unable to book the cost properly, which delays your payment while they ask for the correct document.

Timing matters too. Many tax systems require the tax invoice to be issued within a set window after the supply — days or weeks depending on the country. The practical habit is simple: delivery note signed or work signed off, tax invoice issued the same day, from your main numbering sequence, with your registration number on it.

The common mistake: treating a proforma as the final bill

The mix-up we see most often is a business that sends a proforma, gets paid against it, and never issues the tax invoice at all. The client cannot reclaim the tax, the sale is missing from the seller’s records, and the discrepancy surfaces at the worst possible time — a tax inspection or the client’s audit. The reverse error exists too: issuing a full tax invoice for a sale that then falls through, which obliges you to cancel it formally with a credit note rather than quietly deleting it.

Keep the two in separate lanes: proformas in their own clearly-labelled series for quotes, deposits and customs; tax invoices in your main sequence for completed work. This invoice generator handles the tax-invoice side — with your tax name, rate and registration details in the profile — and the quote generator covers the priced-offer stage before work begins. Use each document for the job its name describes, and your paperwork will survive anyone’s audit.