Know the Diff

Clear differences between common trade documents and order documents. See glossary.
Last updated: 2026-02-11 Autofill Dots
Proforma Invoice vs Commercial Invoice Purchase Order vs Sales Order Sales Order vs Standard Invoice Tax Invoice vs Standard Invoice Proforma Invoice vs Quotation

Typical flow (simplified)

Not every business uses every document, but this sequence is common.
Quotation → Purchase Order (PO) → Sales Order (SO) → Proforma Invoice (optional) → Shipment / Delivery → Commercial / Standard Invoice
Document Main purpose When issued Common use cases
Quotation Price/terms offer Before order is confirmed Bidding, price negotiation, budgeting
Purchase Order (PO) Buyer’s order/authorization When buyer commits to purchase Procurement control, approvals, commitment tracking
Sales Order (SO) Seller’s order confirmation (internal) After seller accepts the order Fulfilment, inventory allocation, delivery planning
Proforma Invoice Invoice-shaped offer / pre-billing Before shipment and/or before final invoice Advance payment, customs estimate, letters of credit
Commercial / Standard Invoice Final bill + trade declaration support On/after shipment or delivery (per terms) Payment request, accounting entry, customs clearance
Note: tax terminology varies by jurisdiction. “Standard invoice” here means the final billing invoice. A “tax invoice” is a final invoice that also includes the tax details required for GST/VAT/tax compliance.

Proforma Invoice vs Commercial Invoice

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Both may look similar, but they are used at different stages and have different legal/accounting weight.
Proforma Invoice Commercial Invoice
What it is Preliminary invoice / offer in invoice format (not the final bill). Final invoice for the actual sale and shipment/delivery.
Primary purpose Confirm pricing/terms; request deposit/advance; support customs valuation estimate. Request payment; support accounting entries; support customs clearance with final values.
When used Before shipment and before the final invoice. On/after shipment or delivery (depending on Incoterms/payment terms).
Accounting / tax Usually does not trigger revenue recognition or output tax by itself (jurisdiction-specific). Typically triggers billing, revenue recognition, and tax/GST/VAT reporting (rules vary).
Document number Often labeled clearly as “PROFORMA” and may have a separate numbering series. Uses official invoice series; referenced by customs, customer AP, and audits.

Use a proforma invoice when

  • You need an advance payment or deposit before producing/shipping.
  • A bank/letter of credit requires an invoice-format document before shipment.
  • The buyer needs a formal document to obtain import permits or budgeting approvals.

Use a commercial invoice when

  • Goods/services have been supplied and you are billing for payment.
  • Shipment is crossing borders and customs requires the final trade invoice.
  • You need an auditable invoice that your customer can pay and book.

Common mix-ups

  • Proforma used as a final invoice: can cause payment, audit, or tax issues if not clearly labeled.
  • Commercial invoice issued too early: may trigger accounting/tax before delivery or before conditions are met.

Purchase Order vs Sales Order

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The PO is created by the buyer; the SO is created by the seller (often internal) after accepting the order.
Purchase Order (PO) Sales Order (SO)
Created by Buyer Seller
Meaning Buyer’s request + authorization to purchase under stated terms. Seller’s acknowledgement/confirmation and internal record to fulfil.
Primary purpose Procurement control; budget approval; contractual reference. Operational execution; inventory allocation; pick/pack/ship planning.
Triggers Buyer commitment (subject to seller acceptance). Fulfilment workflow (shipping, delivery, invoicing).
Key fields PO number, items, quantities, agreed price, delivery terms, billing/shipping details. SO number, items/quantities, promised ship date, fulfilment status, references to PO/quote.

If you’re the buyer

  • Use a PO to formalize purchasing and control spend.
  • Ask the seller to reference your PO number on all invoices and delivery documents.

If you’re the seller

  • Create an SO after you accept the PO (or after a customer order is accepted).
  • Use the SO to drive picking, packing, shipping, and partial fulfilments.

Common mix-ups

  • Assuming PO = accepted: a PO is an offer/order; acceptance may depend on the seller’s confirmation (SO) or written acceptance.
  • Using SO as a customer-facing contract: many companies keep the SO internal and rely on PO/quote/terms for contract language.

Sales Order vs Standard Invoice

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An SO is an order record for fulfilment. An invoice is a billing document that requests payment.
Sales Order (SO) Standard Invoice
Main job Manage fulfilment (what to ship/deliver, when, and to whom). Bill the customer (what is owed, due date, taxes, payment details).
Issued to customer? Sometimes (as order confirmation), but often internal. Yes (this is the customer-facing bill).
Triggers payment? No (by itself). Yes (payment terms apply from invoice date or delivery date, depending on agreement).
Accounting impact Usually none directly; may reserve stock or create commitments. Typically creates accounts receivable and revenue/tax entries (rules vary).
Partial fulfilment Tracks backorders, split shipments, and fulfilment status. Can be issued per shipment/delivery or milestone billing (depends on policy).

Practical rule

  • If operations need to pick/pack/ship, you need an SO (or equivalent order record).
  • If finance needs to collect money, you need an invoice.

Tax Invoice vs Standard Invoice

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A standard invoice is the general billing document. A tax invoice is a billing document that also includes the tax details required for GST/VAT/tax reporting.
Standard Invoice Tax Invoice
What it is A general invoice requesting payment for goods or services supplied. An invoice that includes the tax information required by law for taxable supplies.
Main purpose Bill the customer for the amount due. Bill the customer and support tax/GST/VAT reporting or input tax claims where applicable.
Tax details shown May or may not show tax details, depending on business practice and jurisdiction. Usually shows supplier tax registration number, tax rate, taxable amount, and tax amount.
When used For ordinary billing where a standard payment request is enough. When the transaction is taxable and local rules require a proper tax invoice format.
Customer use Used mainly for payment processing and internal accounts payable. Used for payment plus tax compliance, audit support, and tax credit/input tax documentation where allowed.
Compliance risk Lower formatting burden, but may be insufficient for tax claims if required tax fields are missing. Must usually meet stricter legal formatting/content rules.

Use a standard invoice when

  • You are not GST-registered business entity.
  • The transaction does not require a formal tax invoice format.
  • Your jurisdiction or transaction type allows simpler invoicing.

Use a tax invoice when

  • You are a GST-registered business entity.
  • Your customer needs the invoice for tax reporting or input tax claims.
  • Law or regulation requires specific tax fields and wording.

Quick rule

  • All tax invoices are invoices, but not all invoices qualify as a tax invoice.
  • If tax compliance matters, make sure the invoice includes the mandatory tax fields for your jurisdiction.

Common mix-ups

  • Calling every invoice a tax invoice: this can confuse customers if the required tax details are missing.
  • Using a standard invoice for a taxable supply: the buyer may not be able to rely on it for tax documentation if local rules require a proper tax invoice.

Proforma Invoice vs Quotation

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Both are “pre-sale” documents. The difference is mostly format, intent, and downstream usage.
Quotation Proforma Invoice
What it is A formal offer stating prices, scope, and terms. An offer / pre-billing document in invoice format.
How it’s used Comparison-shopping, approvals, tendering, negotiation. Advance payment request, bank/LC paperwork, customs estimate or pre-shipment documentation.
Looks like Usually has quote number, validity date, scope, exclusions, and terms. Usually looks like a real invoice but must be clearly marked “PROFORMA”.
After acceptance Often becomes the basis for PO/contract. Often followed by a commercial/standard invoice after shipment/delivery.

Quick decision

  • If the customer is still deciding or negotiating: Quotation.
  • If the customer already agreed and needs an invoice-format document for payment/bank/customs steps: Proforma invoice.

Common mix-ups

  • Missing validity dates on quotations: can cause disputes when prices change.
  • Proforma treated as a tax invoice: avoid unless your jurisdiction explicitly allows it.

Reminder

Terminology and tax treatment (GST/VAT) can vary by jurisdiction and by your contract terms. Use clear labels such as “Proforma Invoice”, “Standard Invoice”, and “Tax Invoice”, and keep numbering series consistent to prevent confusion.