How Long Does a Thai Annual Audit Take? Timeline and Preparation

How long does a Thai annual audit take, and when should we start preparing?

2026-10-06

1. Working back from the deadline (year ending 31 December)

When	Work
December	Pre-audit: stock count arrangements, confirmation requests, resolving known issues early
January	Close the books, make year-end adjustments, submit audit records
February–March	Auditor fieldwork on site or remotely, agree adjustments, issue the audit report
By end of April	Shareholders' meeting approves the audited statements
May	File with the DBD and submit PND.50

2. What slows an audit down

Incomplete monthly books, with catch-up done at year end;
No stock count records, or large differences between books and physical stock;
Related-party transactions (balances with head office, service fees, loans) without contracts or reconciliations;
BOI and non-BOI business not accounted for separately;
Slow replies to bank and receivable/payable confirmations.

3. How to make the audit quick and smooth

Keep and reconcile the books every month so nothing piles up at year end;
Agree the stock count date and confirmation list with the auditor before year end;
Prepare contracts, statements and pricing explanations for related-party transactions in advance;
If the audit must support head office consolidation, agree the reporting format early (see How can a Thai audit report support head office consolidated statements?).

4. Basis and scope of service

Basis: Civil and Commercial Code on shareholders' meetings and approval of financial statements; Accounting Act and Accounting Profession Act on audits; auditing standards of the Federation of Accounting Professions (TFAC). Audit timings are typical estimates; actual timing depends on company size, business complexity and record quality. The audit must be performed by a Thai CPA (see What qualifications must an institution hold to issue a Thai annual audit report?).

Related services: Audit Services | Accounting & Tax Outsourcing

What does the Thai Revenue Department usually examine in a tax audit, and how should we respond to a notice?

The Revenue Department most often examines input VAT, missed withholding tax, deductibility of expenses and related-party transactions. VAT refund claims, long-running losses and inconsistent filings are common triggers. On receiving a notice, appoint one contact, provide documents within the requested scope and keep written records; if you disagree with an assessment, you can appeal within the set period.

Our books were not kept properly and are a mess. How do we catch up?

Gather bank statements, invoices and contracts, rebuild the books month by month, then reconcile against the tax returns already filed and correct any differences. The sooner you act, the lower the surcharges; leaving it until a tax audit or the annual audit is the most expensive option.

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FAQ

1. Working back from the deadline (year ending 31 December)

2. What slows an audit down

3. How to make the audit quick and smooth

4. Basis and scope of service