Unpaid invoices in Thailand: an evidence checklist before a payment demand or lawsuit

If a customer in Thailand has not paid for goods, first establish who owes the money, the basis of the obligation, when payment was due and how much remains outstanding. Then assess a payment demand, negotiation or litigation. Contracts, orders, delivery records and payments need to be linked. WeChat, LINE and email records are also worth preserving, but a few screenshots will rarely show the entire transaction.

This article covers document preparation for ordinary business transactions involving goods. Family, inheritance and transactions requiring a particular legal form need separate examination; this checklist should not be applied to them automatically. The claim, applicable law, competent court and relevant deadlines depend on the contract and the transaction facts.

Identify the debtor before treating a contact person as liable

Gather the contract, quotations, purchase orders, invoices, receiving and paying account details, and company information supplied by the other party. Compare the names, addresses and each party’s role in the transaction.

In particular, identify who signed the contract, who placed the orders, who received the goods and who made earlier payments. Where different group companies, distributors, agents or individual contacts participated, do not assume that the person handling communications is the party responsible for paying for the goods.

List inconsistencies in names across documents, third-party accounts and uncertainty about which company a contact represents. Keep the related correspondence available for further checks.

Connect the agreed terms and delivery records for each order

Create a document group for each order rather than mixing every file in one folder. Where available, include:

• The contract, quotation and purchase order, together with records of the other party’s acceptance;
• The price, quantity, payment terms, delivery terms and later changes;
• Dispatch notes, transport records, signed receipts, delivery photographs or system records;
• Acceptance records, quality complaints, returns, replacements and supplementary deliveries;
• The corresponding invoice, payment evidence and outstanding amount.

If the customer raised a concern about quality, quantity or late delivery, preserve the feedback given at the time and both parties’ responses. Collecting only favourable records may overlook issues that affect the recovery options.

Even without a complete signed contract, preserve quotations, order confirmations and performance records, then assess whether they establish the relevant agreement. Do not fabricate signatures, orders or receipt records.

Prepare a separate reconciliation of the outstanding balance

List the order number, invoice number, currency, agreed payment date, original amount, payments received, discounts or refunds, and the outstanding balance claimed. Identify the document supporting each figure.

Keep principal, interest, contractual penalties and other charges separate. If the amount now sought differs from the contract amount, explain the difference. Where there have been several partial payments, payments in different currencies or disputes about how payments were allocated, preserve the original records and the calculation method.

This reconciliation is an organising tool. It does not mean that the customer has admitted every amount, and it does not replace examination of the basis for each claim.

WeChat, LINE and email: preserve integrity and provenance

Section 11 of Thailand’s Electronic Transactions Act prohibits rejecting evidence solely because it is electronic. Its evidential weight still depends on factors including the reliability of how it was created, stored or communicated, its integrity and the sender’s identity. Evidence not being excluded because of its electronic form and evidence proving the entire claim therefore require separate assessment.^{[ETDA Act text, section 11][ETDA electronic evidence FAQ, question 1]}

To help address these questions, consider the following where practicable:

• Keep the original phone, account and original emails or files, rather than forwarded copies alone;
• Preserve the complete sequence of order confirmations, delivery discussions, objections, payment demands and replies;
• Keep provenance information such as account identifiers, email addresses, sending times and attachments;
• Number readable screenshots or printouts so that they can be matched to the original records;
• Record who obtained and preserved the material, when and by what method.

These are document preparation suggestions, not a uniform statutory retention obligation or submission checklist for every case. Further checks may be needed if the other party disputes the account holder’s identity or a message’s authenticity or completeness.

Where the law requires documents or information to be retained, section 12 sets conditions for electronic retention, including accessibility without changing the meaning, accurate reproduction, and preservation of available origin, source, destination and sending or receipt date and time information. It is subject to section 10. This does not mean that every screenshot is equivalent to an original.^{[ETDA Act text, section 12]}

Translations, selected extracts and annotated versions can aid reading, but keep them separately from the unedited material so that their relationship to the original can be explained.

Check what a formal payment demand will say

A payment demand should clearly explain the transaction basis, amount claimed, calculation method and issues the customer is being asked to address. Preserve the text sent, attachments and relevant delivery or reply records.

If instalments, discounts, an extension of time or settlement in exchange for a partial payment have already been discussed, provide the complete correspondence to the person handling the matter. Any new wording may relate to those arrangements; the original invoice amount should not simply be reused without checking.

The effect of a payment demand, lawyer’s letter or negotiation on limitation periods, interest or termination requires separate assessment. Do not assume that sending a notice restarts every deadline. Where the relevant period is unclear, check it promptly so that waiting for a reply does not delay necessary procedural steps.

Provide a one-page factual summary for an initial recovery discussion

The summary can identify the parties, goods and orders, delivery history, payment due date, outstanding balance, the customer’s main objections and payment demands already made. Add a document index and flag missing originals, inaccessible accounts or translations that are not yet available.

This helps the discussion focus on the actual dispute and the next step: additional evidence, further negotiation, legal documents or a litigation assessment.

If a Thai judgment has already been obtained, the matter is at a different enforcement stage. Read Thailand judgment enforcement and debt recovery for issues to consider between obtaining a judgment and receiving payment.

For an unpaid claim where no judgment has been obtained, explain the current stage and refer to the debt recovery and enforcement service page and the civil litigation service page for information on documents and the scope of work.

Frequently asked questions