Accounting + Tax + Payroll Retainer

What a Thai company must file, and on what calendar

Every juristic person registered in Thailand carries three parallel obligations: bookkeeping under the Accounting Act B.E. 2543, tax filing under the Revenue Code, and social security registration for employees. Foreign-owned companies are treated identically to Thai-owned ones on all three; the only differences appear where a BOI promotion or a Foreign Business Licence attaches extra reporting to the promoting agency.

The most common failure we are asked to repair is not fraud but calendar drift. A company files VAT late for three consecutive months, the surcharge compounds, and by the time the annual audit is prepared the arrears exceed the cost of a year of professional bookkeeping. Thai penalties are arithmetic rather than discretionary, so drift is expensive in a predictable way.

Bookkeeping standards a foreign director should insist on

• Accounts kept in Thai and in Thai Baht as the statutory record, with a parallel English management pack so the board can actually read what it approves.
• A licensed accountant registered with the Department of Business Development named as the responsible bookkeeper — this is a person, not a firm, and the registration number appears on the filings.
• An independent CPA auditor for the annual statements; the bookkeeper and the auditor must not be the same person.
• Withholding tax certificates (50 ทวิ) issued at the moment of payment, not reconstructed at year end, because the counterparty needs them for its own credit claim.
• A fixed-asset register that matches the depreciation schedule used in PND.50, since mismatches are a standard Revenue Department audit trigger.

Payroll for companies employing foreigners

Payroll for a foreign employee has to reconcile with two other files: the work permit and the visa extension. Immigration and the labour authorities compare the salary stated on the work permit application, the salary in the PND.1 filings, and the salary in the extension paperwork. A company that pays part of a foreign salary offshore to reduce Thai withholding creates a visible gap between those three files, and the gap surfaces at the extension counter rather than at the tax office.

Thai personal income tax is progressive and is withheld monthly by the employer, with a year-end reconciliation on PND.91 for the individual. Social security applies to foreign employees on the same terms as Thai employees where the employment is local. Where a home-country social security agreement exists, the treatment depends on the specific agreement; we check the text rather than assuming exemption.

How we take over a set of books mid-year

1. Reconstruct the trial balance: We rebuild from bank statements, VAT reports already filed, and the previous auditor's working papers rather than trusting an unverified spreadsheet.
2. Quantify arrears exactly: Surcharge and penalty are computed per filing and per month so the board sees a number, not an estimate, before deciding on a voluntary correction.
3. File corrections in statutory order: Withholding first, then VAT, then corporate tax, because later filings depend on figures established by the earlier ones.
4. Reset the calendar: A filing calendar with internal cut-offs five days ahead of each statutory date, so a missing supplier invoice is chased before the deadline rather than after it.
5. Prepare for audit: Working papers, related-party schedules and a director's representation pack assembled before the CPA arrives, which is what keeps audit fees stable.

Common mistakes and how we avoid them

More questions we are asked

Can a dormant company skip filings?

No. A company with no transactions still files nil returns, holds an AGM, and submits audited statements. Dormancy reduces work; it does not remove obligations.

Must the books be in Thai?

The statutory record is kept in Thai. An English management pack is permitted and advisable in parallel, but it is not the filing record.

Does a BOI promotion change the tax calendar?

The calendar is the same. What changes is the additional reporting to the promoting agency and the segregation of promoted and non-promoted income in the accounts.

Who is personally liable for late filing?

Thai law attaches penalties to the company and, for several offences, to the authorised directors personally. This is why we report arrears to the board in writing.