Three documents — invoice, quote, and proforma invoice — look almost identical at first glance. They all contain prices, client details, and line items. But they serve fundamentally different purposes, carry different legal weight, and sending the wrong one at the wrong time can lead to disputes, delayed payments, or tax complications. This guide clarifies each one.
Quick Comparison
| Document | Purpose | Legally binding? | Triggers payment? | When sent |
|---|---|---|---|---|
| Quote / Estimate | Price proposal before work begins | Sometimes (if signed) | No | Before work starts |
| Proforma Invoice | Preliminary invoice for advance payment or customs | No | Sometimes (for deposits) | Before goods/services delivered |
| Invoice | Formal payment request after work is done | Yes | Yes | After delivery |
What Is a Quote (or Estimate)?
A quote — also called an estimate, proposal, or tender — is a document you send to a potential client before any work begins. It says: "Here's what I'll do, and here's what it will cost."
A quote is a business proposal, not a payment request. The client hasn't agreed to pay anything yet. They may accept it, reject it, negotiate it, or simply not respond.
Key characteristics of a quote:
- Sent before any work begins
- States estimated or fixed prices for proposed work
- Has an expiry date (e.g. "Valid for 30 days")
- Not a tax document — it does not need a VAT number or tax breakdown in most countries
- Becomes binding only when both parties formally accept it (usually in writing)
Difference between a quote and an estimate:
A quote is a fixed price — if the client accepts it, you do the work for exactly that amount. An estimate is an approximation — the final price may vary based on actual hours or materials. Always be clear which one you're sending.
When to use a quote: Always before starting work for a new client, for a large or complex project, or wherever there could be ambiguity about what's included in the price.
What Is a Proforma Invoice?
A proforma invoice is a preliminary invoice sent before goods are delivered or services are fully rendered. The word "proforma" is Latin for "as a matter of form" — it's a document that looks like a final invoice but isn't one yet.
Proforma invoices are used in two main situations:
- Advance payments and deposits — you send a proforma invoice to request a deposit or upfront payment before starting work. The client pays against the proforma, and you issue a final invoice later.
- International trade and customs — importers often need a proforma invoice to apply for import licences, arrange foreign currency, or clear goods through customs before the final invoice exists.
Key characteristics of a proforma invoice:
- Clearly marked "PROFORMA INVOICE" — not just "INVOICE"
- Not a tax invoice — does not count for VAT/GST purposes
- Not a legal demand for payment — it's an offer of a price
- Used to request deposits or facilitate imports
- A final invoice must be issued once the transaction is complete
Important: A proforma invoice cannot replace a final invoice for tax purposes. If your client asks for a VAT receipt, you need to issue a proper tax invoice — not a proforma.
What Is an Invoice?
An invoice is the final, formal payment request issued after you have delivered the goods or completed the services. It is a legally binding document that creates an obligation for the client to pay the stated amount by the stated date.
Key characteristics of a final invoice:
- Issued after delivery of goods or completion of services
- Legally binding — the client owes you the stated amount
- Required for accounting and tax records on both sides
- Must include all required fields (see our invoice writing guide)
- Can be used as evidence in a legal dispute over non-payment
- For VAT-registered businesses: the invoice is the VAT record — clients use it to reclaim input tax
The Correct Document Workflow
For most projects, the typical document flow looks like this:
- Quote / Estimate → sent to client before work begins. Client reviews and approves.
- Proforma Invoice (optional) → sent if you need a deposit. Client pays the deposit.
- Work completed → you deliver the goods or services.
- Final Invoice → sent after delivery. Client pays the balance.
For smaller, simpler jobs — particularly between established business relationships — the quote and proforma steps are often skipped. You agree the price verbally or via email, complete the work, and send the invoice.
Common Mistakes
- Sending a proforma instead of a final invoice — some clients will use this to delay payment indefinitely, since a proforma isn't a legal payment demand.
- Not marking the document type clearly — always put "INVOICE", "PROFORMA INVOICE", or "QUOTE" prominently at the top. Ambiguity creates disputes.
- Treating a verbal quote acceptance as a contract — get it in writing. Email confirmation is sufficient, but a signed quote is better for large projects.
- Using a quote or proforma as a VAT record — only a final invoice (with your VAT number and a proper tax breakdown) counts for VAT purposes.
Free Templates for Each Document
InvoiceCreatorFree has dedicated templates for all three document types: