Quotation vs. invoice: which one do you send, and when?
The difference between a quotation, a proforma invoice, a tax invoice, and a receipt — and the exact moment in a deal to send each one.
Small businesses lose money in the gap between "we agreed" and "I got paid." The documents you send at each stage close that gap. Here is the sequence.
1. Quotation — before the work
A quotation is your offer: items, prices, validity period. It is not a demand for payment and has no tax consequences. Send it when the client asks "how much?" — and always give it an expiry date, because your costs change.
2. Proforma invoice — when they say yes
A proforma looks like an invoice but is labeled proforma — it is a preview of the final bill, often used for advance payments or customs. It still does not create a VAT obligation.
3. Tax invoice — when you deliver
The tax invoice is the legal document. In Oman it must carry your VATIN, sequential number, and the 5% VAT breakdown. Issue it at delivery (or per your contract's milestones). This is the moment your VAT liability is born — date it correctly.
4. Receipt — when money arrives
A receipt confirms payment received against an invoice. Attach the proof — bank transfer screenshot or cash note — and your records reconcile themselves at tax time.
The golden rule
One deal, one paper trail: quotation → (proforma) → tax invoice → receipt, all pointing at each other by number. When a client disputes a price six months later, you answer in thirty seconds instead of thirty minutes.