Invoice vs quotation: what is the difference?

Invoice vs quotation: the key difference

A quotation describes an offer before a customer confirms a purchase or project. It normally sets out the proposed products or services, quantities, prices, scope, validity period, and commercial terms. An invoice records an amount charged or due under a transaction and communicates billing and payment information. The exact point at which an invoice is issued depends on the agreement and local rules.

Side-by-side comparison

These are common business practices, not universal legal definitions. Some quotations become binding when accepted, and some invoices are issued before delivery or completion under agreed advance-billing arrangements.

Worked example: supplying office chairs

A furniture supplier is asked to provide 10 office chairs at $120 each, with a 5% discount and a $50 delivery charge. Before the customer commits, the supplier sends a quotation showing the offer and its validity period.

Illustrative amounts in USD — not tax advice. The amounts below exclude tax for simplicity.

After the customer accepts, the supplier may prepare an invoice for $1,190 at the agreed billing stage, provided the quantities, prices, delivery charge, and other terms remain unchanged. If tax applies, it must be calculated according to the relevant rules rather than assumed from this example.

When should you send a quotation?

Use a quotation when a prospective customer needs to approve a price or scope before proceeding. It is particularly useful for custom furniture, construction, repairs, catering, maintenance, design services, and orders with variable quantities. Include enough detail to prevent misunderstandings about what is included and excluded.

When should you issue an invoice?

Issue an invoice when the transaction reaches its agreed billing point. That may be after delivery, on completion of a service, at a project milestone, or in advance if the contract permits. Confirm the customer, description, amounts, currency, applicable taxes, payment terms, and due date before sending it.

How a quotation becomes an invoice

1. Prepare a quotation with clear descriptions, quantities, prices, and conditions.
2. Send it to the customer for review.
3. Record acceptance and any agreed changes.
4. Confirm what was actually supplied or the milestone reached.
5. Create an invoice using the accepted terms, updating dates, taxes, quantities, and charges as necessary.
6. Review the final invoice before sending it and retain both documents for your records.

BizDoc Maker supports a quotation-to-invoice workflow, but you should still verify the resulting invoice because the agreed offer and the final bill may differ.

Do you always need both documents?

No. A straightforward sale with an agreed price may proceed directly to an invoice. A customized project may need a detailed quotation first. An accepted quotation does not automatically replace every invoice, receipt, or tax document that local rules require.

Common mistakes to avoid

• Treating a quotation as a payment demand: Make it clear whether the document is an offer or a bill.
• Omitting a validity period: State how long quoted prices remain available when appropriate.
• Changing prices without agreement: Document revisions and obtain acceptance where needed.
• Billing the wrong quantity: Reconcile the invoice with actual delivery and agreed terms.
• Forgetting delivery charges or discounts: Show the relevant adjustments transparently.
• Assuming all tax rules are identical: Check the requirements for your country and transaction.
• Using unclear document numbers: Give quotations and invoices distinct references to simplify recordkeeping.

How to make each document with BizDoc Maker

1. Open the Quotation Generator when you need to propose a price.
2. Enter seller and customer information, line items, and commercial terms.
3. Check the live preview and save or print the quotation as appropriate.
4. Once the offer is accepted, prepare an invoice through the supported conversion workflow or the Invoice Generator.
5. Review the billing date, due date, amounts, and any applicable tax before printing or saving the invoice as PDF.

Frequently asked questions

Is a quotation legally binding?

It can be, depending on its wording, acceptance, and applicable law. Do not assume every accepted quotation is nonbinding or that every quotation is automatically a contract.

Can I invoice a customer before delivering goods?

Sometimes. Advance invoices or milestone billing may be part of an agreed transaction. Check the contract and local invoicing and tax requirements.

Can the final invoice differ from the quotation?

Yes, if the parties agree to changes or the quotation allows specified adjustments. Explain any differences clearly and retain the relevant approvals.

Does a quotation prove payment?

No. A quotation describes an offer. A receipt normally records payment received, while an invoice documents the billed amount.

Should quotation and invoice numbers be the same?

They generally serve different recordkeeping purposes. Use clear, distinct identifiers and refer to the quotation number on the invoice when helpful.

Is a quotation the same as a pro forma invoice?

Not necessarily. Both can describe a proposed transaction, but their intended uses and any customs, tax, or contractual implications may differ. Follow the requirements relevant to the transaction.

Note: Document and tax requirements vary by country, industry, and transaction. This guide provides general business information, not legal or tax advice. Check applicable local rules when necessary.