New business owners encounter documents from quoting a job through payment and withholding tax. This guide groups five common documents by their role in a workflow. It is a record-keeping overview, not a rule that every business must issue every document for every transaction.
1. Quotation: agree on scope and price
A quotation summarizes the items or work, quantities, prices, terms and validity period before work starts or goods are supplied. State whether prices include tax and whether extra charges may apply. A quotation is part of the sales process; it is not automatically a tax invoice or proof of payment.
2. Billing note or invoice: request payment
A billing note or invoice tells a customer what amount is due and when. It can identify the document number, related job or purchase order, due date and payment method. Names and formats vary by business. Make clear what the charge covers, and do not treat a request for payment as proof that payment has been received.
3. Delivery note and tax invoice: distinguish delivery from tax records
A delivery note records items and handover under a business’s own process. A tax invoice is part of the VAT system. Under Section 86 of Thailand’s Revenue Code, a VAT-registered operator must issue a tax invoice when VAT liability arises, subject to applicable exceptions and conditions.
A delivery note, billing document and tax invoice may be separate or combined when the applicable requirements are met. Do not assume every delivery note can replace a tax invoice. Check the relevant VAT requirements under Sections 85–86 of the Thai Revenue Department’s guidance before setting up a document template.
4. Receipt: confirm payment received
A receipt records how much was received, from whom and when, and which debt or invoice it relates to. Keep “billed” separate from “paid” in the accounting records. If a receipt is combined with a tax invoice, check that the tax document includes the required information. A general receipt is not a tax invoice in every case.
5. Withholding tax certificate (50 bis)
When a payer is required to withhold tax, Section 50 bis provides for issuing a withholding tax certificate to the person whose income was withheld. The issue date varies with the income type and the conditions set by law. Check Section 50 bis and the Revenue Department certificate form. The recipient should keep the certificate and match it to the relevant income and tax entry.
Arrange records so they can be traced later
- Keep the quotation and evidence that the customer approved the scope.
- Use matching job or purchase-order references on billing and delivery documents.
- Issue tax documents according to the transaction and applicable conditions; do not substitute one document type for another automatically.
- When payment arrives, record the receipt and payment evidence against the correct amount.
- If tax was withheld, match the certificate to the income and tax amount for that transaction.
The sequence can differ with the business model, VAT registration and payment terms. Set numbering and record-retention practices for the business, and ask an accountant to review templates before use. This is general information, not a tax ruling for a specific transaction.
Related reading and original video
For another guide to withholding tax certificates, see How to read a withholding tax certificate. The original source is TAXBugnoms’ overview of five accounting and tax documents.