A Thai company must keep its accounting records and supporting documents for at least five years from the closing of the accounts, and the Revenue Department can summon them in an audit. Complete books, invoices, withholding certificates and bank statements, indexed by month, turn an audit into a routine check.
The Accounting Act requires a company to keep accounts and the documents behind them in good order. The books must be preserved for at least five years from the closing date of the accounts, and the Revenue Code allows the Department to examine tax records within its own limitation periods, which can be longer in cases involving suspected fraud or unfiled returns.
The documents include ledgers and journals, sales and purchase invoices, tax invoices, withholding certificates, bank statements, payroll records, contracts and board minutes. Digital copies are acceptable if they are retrievable and faithful, but the originals of some paper documents should be retained until the accountant confirms otherwise.
A sensible policy is to retain everything for ten years unless a specific rule says otherwise, and to destroy documents only after a recorded decision. Disposal with personal data inside must also respect the PDPA.
Revenue audits begin for several reasons: a risk score generated from the returns, a refund claim, an inconsistency between a company’s returns and those of its customers or suppliers, a tip-off or a random selection. Being small does not make a company invisible, because information from banks and other agencies feeds the Department’s analysis.
The first sign is usually a letter requesting documents or inviting the company to a meeting. It will list the period and the taxes in question, and set a deadline. Responding on time and politely matters more than people expect; officers have discretion, and a cooperative taxpayer with orderly records often settles faster.
If you receive such a letter, tell your accountant the same day, read the request carefully and ask for clarification of anything unclear in writing.
Organise documents by tax month. For each month keep the PP.30, the PND returns, the ledger extracts that tie to them, the invoices and a short reconciliation of VAT and withholding to the general ledger. An inspector who can trace a figure from the return to the underlying invoice in a few minutes will ask fewer follow-up questions.
Keep a contracts folder with the signed agreements behind major sales and purchases, because the Department may query the substance of transactions, such as service fees paid to related parties. Keep evidence of delivery or performance as well as the invoice.
Maintain an index. A one-page list of where each category of document is stored, who is responsible for it and when it was last checked helps the team respond quickly, and it survives staff turnover.
Appoint one person to be the contact with the officers and keep a log of every document handed over. Provide what is requested, in the form requested, and do not volunteer unrelated material. If a document is missing, say so and explain what alternative evidence exists rather than improvising.
Where the officers propose adjustments, ask for the legal basis and the calculation in writing. If you disagree, your accountant or tax lawyer can respond and, if needed, use the appeal process. Agree to a settlement only after the numbers have been checked.
Keep the tone professional. Audits are routine for the Department, and a respectful, organised response works better than defensiveness.
Issued sales invoices can be generated as PDFs and stored in the 4invoices archive, and your accountant can keep the ledgers in 4softerp. HR records for employees, leave and timesheets sit in 4softhr and are useful when payroll costs are queried.
These products store what you put in. They do not guarantee that your records meet the Thai retention rules, produce Revenue Department reports or represent you in an audit. Retention policy, the legal view and the response to the Department remain with you and your advisers.
Most Thai companies now work with digital documents: invoices arrive as PDFs, bank statements are downloaded and contracts are signed electronically. The convenience hides a risk, because a document that exists only in an employee’s mailbox or on a personal phone can disappear with the employee or the device.
Choose a single storage location that the company controls and back it up to a second location. Use a naming convention that begins with the date and the document type, so a search by month brings up a coherent set. Test restoring a backup once a year, since an untested backup is a hope rather than a control.
Protect access. Accounting folders contain tax IDs, salaries and bank details, so limit access to those who need it, remove access when staff leave and keep a log of who changed what where the tool allows it. A leak of payroll data is both a PDPA problem and an employee-relations problem.
Finally, plan for the unexpected. If the office is flooded, the server fails or the accountant is unreachable, what is the minimum set of documents needed to file the next month’s returns? Write down where those documents are and who can get to them.
Review this plan whenever the accountant, the bank or the storage provider changes. Many companies discover during an audit that the person who knew where everything was left two years earlier, and that the instructions existed only in that person’s head.
A short annual drill helps: ask a colleague who did not prepare a given month to find three documents for it, such as one sales invoice, one supplier invoice and the bank statement. If that takes more than a few minutes, the index needs work before an inspector tests it for you.
Documents are kept in individual staff mailboxes and lost when people leave.
Store documents in a shared folder organised by tax month and keep an index. The system holds the invoice PDFs you issue, but supplier documents need your own filing routine.
The company cannot explain why the PP.30 figure differs from the ledger.
Prepare a monthly reconciliation of the returns to the ledger and keep it with the return. Your accountant produces it; the system does not compare returns to books.
An audit letter arrives while the accountant is away and nobody knows the deadline.
Name a deputy for tax matters and agree that any official letter is photographed and sent to both the same day.
The Accounting Act requires accounts and supporting documents to be kept for at least five years from the closing of the accounts. The Revenue Department can examine records within its own limitation periods, which may be longer where fraud is suspected or returns were not filed, so many companies keep records for longer.
Digital copies are generally accepted if they are complete, readable and retrievable, but certain originals should be kept until your accountant confirms that the digital copy is enough. Back the scans up in more than one place and document how they are indexed, so that you can produce them quickly on request.
Typical triggers include a refund claim, figures that look unusual against comparable businesses, mismatches between your returns and those of your customers or suppliers, and information from third parties. Small companies are audited too, so keep records in order from the first month rather than only after you receive a letter.
Read the request, note the deadline and send it to your accountant the same day. Collect the documents for the period and taxes named, keep a log of everything you hand over and answer in writing. If you need more time, ask for it before the deadline passes, not afterwards.
Only after checking that no inquiry is open and that no longer retention rule applies to those documents, and after a recorded decision by the company. Documents containing personal data must be destroyed securely, because the PDPA applies. When in doubt, keep them, as storage costs less than a dispute.
A PDF invoice archive and multi-company books. Retention rules and audit responses are managed with your advisers.
