Proforma Invoice: What It Is, When to Use One, and How to Write It
A potential client says yes — then asks for a "proforma invoice so we can raise a PO." It\u2019s the most commonly confused document in the invoicing chain: a quote wearing an invoice\u2019s clothes. This guide covers what it is, when to send one, what to put on it, and how to convert it into the real thing.
By KSP Labs, Software Studio behind Billify · Updated September 2026
Need to send one today? Open the free editor (no signup) — label it "Proforma", number it in its own PI- sequence, and convert it to a final invoice in one click when the deal confirms.
Open the free invoice editorWhat a proforma invoice actually is (and isn\u2019t)
The word proforma is Latin for "as a matter of form" — and that\u2019s exactly right: it\u2019s an invoice in form only. It presents everything a final invoice would — seller, buyer, line items, totals, currency, validity — but it\u2019s issued before the sale is final and is not a demand for payment. Three things make it a proforma: it\u2019s marked "PROFORMA INVOICE", it doesn\u2019t assert that money is due, and it usually carries an expiry date.
What it is not: a tax document. In almost every jurisdiction a proforma isn\u2019t recorded as output VAT/sales tax, doesn\u2019t appear in your VAT return, and doesn\u2019t belong in your ledger as an issued invoice. It lives in your sales pipeline — until you convert it.
When to send one (5 real situations)
You need a proforma when a third party — a procurement system, a bank, a customs office — needs something that looks like an invoice before the real one can exist.
1. The client’s procurement process requires one
Large companies, universities, and government bodies often can’t "just pay a freelancer." Their system needs an invoice-shaped document to attach to a purchase order. The proforma is the bridge: it gets you into the PO system before work begins — the single best predictor of getting paid on time.
2. International trade and export shipping
The classic use: a proforma for customs declares goods, quantities, values, currency, Incoterms, HS codes, and country of origin before shipment, so the buyer can arrange import clearance, a licence, or a letter of credit. Ship physical goods abroad without proforma paperwork and expect delays or a bonded-warehouse bill.
3. Deposits and milestone payments
Want 50% up front? Put it on a proforma. State the full price and name the deposit amount and trigger ("50% deposit, €1,750, payable on acceptance"). The client pays the deposit against the proforma; you invoice the balance later. No half-paid "invoice" sits in receivables.
4. Letters of credit and international payments
Banks issuing L/Cs work from documents. The proforma is typically the base document the buyer presents to open the letter of credit — and the commercial invoice must later match it. Mismatched totals or descriptions are the most common reason L/C payments get rejected.
5. Confirming scope before you build
A proforma forces you to write down deliverables, quantities, unit prices, dates, and terms in a format the client has seen a hundred times. "Sign off on this proforma and we start Monday" is contract-lite that catches scope misunderstandings while they’re still free to fix.
Proforma vs. quote vs. invoice vs. commercial invoice
Four documents, one family. A quote negotiates, a proforma commits to terms without demanding payment, an invoice demands payment, and a commercial invoice demands payment across a border.
| Quote / Estimate | Proforma invoice | Invoice | Commercial invoice | |
|---|---|---|---|---|
| When sent | Before the deal | After agreement, before work/shipping/payment | After delivery or per terms | With shipped goods, for export |
| Legal weight | Usually none | Usually none (see below) | Demand for payment — enforceable | Demand for payment + customs document |
| Tax point | No | No | Yes — VAT/sales tax recorded | Yes |
| Looks like | Letter or proposal | Invoice | Invoice | Invoice + shipping fields |
| In your invoice sequence? | No | Preferably separate (PI-) | Yes | Yes |
| Who needs it | The decision-maker | Procurement, customs, banks, L/C | Accounts payable | Customs brokers |
If a client asks you to "re-send the quote as a proforma invoice," they\u2019re not being pedantic — their organization can\u2019t process a quote, but it can process an invoice-shaped document. Convert it; you\u2019re changing the wrapper, not the deal. See also the invoice field checklist and the payment terms guide.
What goes on a proforma invoice, field by field
A proforma carries everything a real invoice does — which is exactly why procurement systems accept it. Follow the same checklist you\u2019d use for a real invoice, with these proforma-specific additions:
Header block
- "PROFORMA INVOICE" — large, unmissable, where "INVOICE" would normally sit. The title does legal work.
- Proforma number — from its own PI- sequence (more below).
- Issue date and validity — "Valid for 30 days" protects you from stale prices and rates.
- A clarifying subtitle — "Proforma invoice — not a tax invoice / not a demand for payment." Belt and braces.
Parties
- Your details — full business name, address, tax ID/VAT number, contacts.
- The client’s legal entity — exactly as procurement knows it ("Acme GmbH", not "Acme"), plus their VAT ID for cross-border work. Quote an existing PO number, or leave a placeholder if the PO is pending.
The deal itself
- Line items — description, quantity, unit, unit price, line total. "Logo design, 3 concepts, 2 revision rounds" is a scope document and an invoice line in one.
- Currency — explicitly stated, especially for international clients.
- Totals and tax note — subtotal, tax line ("VAT to be applied on final invoice" / "reverse charge applies"), and total.
- Deposit — amount, percentage, and payment trigger, if you’re taking one.
- Payment terms — the ones you intend to apply (see the payment terms guide).
Shipping fields (goods only)
- Customs data — Incoterms with named place, estimated ship date, transport mode, HS/tariff codes, country of origin, weights, package count. Customs officers reject shipments for missing any of these.
Footer
- Acceptance line — "Accepted by — name, date" if you’re using it as scope confirmation.
- Bank details — only if the proforma requests a deposit. Otherwise leave them off, so a junior AP clerk can’t mistake it for a payable bill.
How to number proformas without wrecking your sequence
Your tax invoice sequence is usually legally required to be continuous — no gaps, no duplicates. Issuing proformas from the same sequence forces an ugly choice: burn real invoice numbers on non-invoices (auditors hate gaps) or reuse numbers (illegal in most jurisdictions).
The clean solution is a separate prefix: PI-0001, PI-0002, PRO-2026-001. Your real sequence stays pure, proformas are instantly distinguishable, "PI-" signals non-payable to procurement, and when the deal converts you reference it — final Invoice #2042 "per proforma PI-0007."
Is a proforma invoice legally binding?
By itself, in most jurisdictions: not as a demand for payment — but not without force. It\u2019s not a tax or accounting document and creates no VAT obligation. You can\u2019t sue on it the way you can on an invoice, because it doesn\u2019t assert that payment is due. But if the client accepts, signs, or pays a deposit against it, that acceptance — combined with your delivery — can form a binding agreement on price and terms. Courts look at conduct, not titles.
The practical rule: a proforma is binding on the deal, not on the payment. Price, scope, and terms — yes, once accepted. Money due — only when the real invoice says so. One caution: a proforma declared to customs is a formal statement — understating values to help a buyer dodge duties is fraud.
Turning a proforma into a real invoice: the conversion checklist
The deal is confirmed, the PO lands, the deposit clears. Seven steps to a clean conversion:
1. Copy the proforma
Duplicate it into your invoice tool — same client, same line items, same totals. With saved client details and templates this is a 30-second job.
2. Change the title to INVOICE
Swap "PROFORMA INVOICE" for "INVOICE" and assign the next number in your real, legally continuous invoice sequence.
3. Reference the proforma
Cite it on the final invoice: "Invoice for engagement per proforma PI-0007, PO #4471." Cross-referencing prevents double-processing and double-chasing.
4. Apply tax properly
The final invoice is where VAT/sales tax actually gets charged and recorded. The proforma never touched your tax ledger; the invoice must.
5. Deduct any deposit
Show the deposit as a line ("Deposit received 12 Aug — thank you") and invoice the balance, so the client isn’t double-billed.
6. Set an explicit due date
"Payment due 30 September 2026" beats "Net 30" for on-time payment — payment runs and AP cutoffs key off exact dates.
7. File the proforma with the project
If payment ever goes sideways, the accepted proforma is the first exhibit in your paper trail.
Frequently asked questions
What is a proforma invoice, in simple terms?
It’s a "draft" invoice sent before work is confirmed or goods are shipped. It shows exactly what you plan to deliver, the price, and the terms — so the client can approve, raise a purchase order, arrange customs, or pay a deposit — but it is not yet a demand for payment and isn’t recorded for tax.
What’s the difference between a proforma invoice and an invoice?
A proforma is issued before the sale is final and requests no payment; an invoice is issued after and is a legally enforceable demand for payment that triggers your tax obligations. Everything else — layout, fields, totals — can look identical, which is exactly why the "PROFORMA" label matters.
Can a client pay a proforma invoice?
Yes — deposits are commonly paid against a proforma, and banks can open letters of credit from one. But if a client pays the full amount off a proforma, still issue the final invoice marked "paid" and reference the proforma: your accounting needs the real invoice, and their AP department does too.
Do I put a VAT number on a proforma invoice?
Include your VAT/tax ID for identification (especially internationally), but make clear no VAT is being charged yet — e.g., "VAT will be applied on the final invoice." The proforma itself never appears in your VAT return.
How long should a proforma invoice be valid?
Common practice is 14–30 days. Long enough for procurement to process a PO, short enough that prices, exchange rates, and your calendar can’t drift out from under it. State it explicitly: "Valid for 30 days from issue."
Proforma invoice or quote — which should I send?
Send a quote while the deal is still being shaped (prices negotiable, scope fluid). Send a proforma once terms are agreed and a third party needs an invoice-shaped document — procurement, customs, a bank, or a deposit payer. When in doubt with a corporate client, send the proforma: nothing stops you from revising it.
Do proforma invoices need a signature?
Not usually required — but a signature line ("Accepted by — name, date") upgrades the proforma from price information into evidence of an agreed deal. If the engagement is substantial, get it signed. It costs nothing and it’s the document you’ll want if payment ever turns into a chase.
Send proformas that convert into paid invoices
The proforma satisfies procurement, clears customs, locks scope, and collects deposits — all before a single euro is due. Label it clearly, number it in its own PI- sequence, put an expiry on it, and convert it the moment the deal confirms.