Proforma Invoice vs Invoice: What's the Difference?

The One-Sentence Difference

A proforma invoice is a preliminary document sent before a sale is confirmed. A tax invoice (or standard invoice) is a formal demand for payment once goods or services have been delivered.

Same layout, completely different legal and accounting meaning.

What Is a Proforma Invoice?

The word "proforma" comes from Latin meaning "as a matter of form." A proforma invoice is essentially a draft invoice — a good-faith estimate of what the final invoice will look like.

You send a proforma invoice when:

A buyer needs to know costs before committing to a purchase

You need to arrange import/export customs documentation

A client needs an internal purchase order approved before you can be paid

You want to confirm line items, quantities, and prices before finalising the deal

A proforma invoice is not a payment demand. It does not create a legal obligation to pay, does not get recorded as income, and should not be entered into accounting records as a receivable.

What Is a Tax Invoice?

A tax invoice (or standard invoice) is issued after the sale is confirmed and the goods or services have been delivered or are being delivered. This is the document that:

Creates a legal obligation to pay

Is recorded as accounts receivable in your books

Triggers the GST/VAT reporting obligation

Serves as the official record for both buyer and seller

In most jurisdictions, a valid tax invoice must include your business registration or GST number, the date, a sequential invoice number, and a breakdown of tax amounts.

Key Differences at a Glance

Purpose: Proforma = estimate/confirmation. Invoice = payment demand.

Legal status: Proforma = not legally binding. Invoice = creates payment obligation.

Accounting treatment: Proforma = not recorded as income. Invoice = recorded as revenue/receivable.

GST/VAT: Proforma = no tax obligation triggered. Invoice = GST/VAT becomes reportable.

Sequential numbering: Proforma invoices are often numbered separately (e.g. PI-001) to keep them out of your invoice sequence.

Common Mistakes

Treating a proforma as a real invoice. Some businesses record proforma invoices as income before goods are delivered or the sale is confirmed. This overstates revenue and creates reconciliation headaches.

Omitting proformas from the workflow entirely. For international shipments, a proforma is often required by customs. For large B2B purchases, it's needed for internal purchase order approval. Skipping it can delay deals.

Confusing clients. If you send a proforma and then a real invoice with the same number, clients may pay the "duplicate" or dispute which one is valid. Keep numbering systems separate.

When to Send Each

Send a proforma when:

The client needs to approve internally before you can proceed

You're shipping goods internationally

The final scope isn't 100% confirmed but the client needs a cost estimate on official letterhead

Send a real invoice when:

The order is confirmed and goods/services are being delivered

You want to formally request payment

You need to record the transaction for tax purposes

Proforma Invoices in Quotation Expert

Quotation Expert handles both proformas and invoices in a single workflow. You can create a quotation (which functions as a proforma), send it for approval, and convert it to a formal invoice with one click once the client confirms. The invoice inherits all the line items, quantities, and prices — no re-entry needed.

The converted invoice is automatically assigned a sequential invoice number and recorded in your accounts. The original quotation is preserved for your records.

This workflow is common in B2B sales: quote → client approves → invoice → payment.