Audit Requirements in Thailand: Who Needs One and When (2026 Guide).

What the audit requirements in Thailand actually say

The audit requirements in Thailand come down to one sentence in one law: a financial statement must be audited and accompanied by the opinion of a certified auditor. That sentence sits in Section 11 of the Accounting Act B.E. 2543 (2000), and it applies to almost every registered business in the country, every year, regardless of size or activity.

The Act names five kinds of entity that carry the accounting duty:

• Limited companies established under Thai law
• Public limited companies
• Registered partnerships established under Thai law
• Juristic persons established under foreign law but operating business in Thailand, which covers branches and representative offices
• Joint ventures under the Revenue Code

If your business is on that list, it must close its books within twelve months of registration and every twelve months after that, prepare financial statements from those books, and have them examined by a licensed auditor before they go anywhere official.

Two points catch people out. There is no size threshold for companies: a limited company with one employee and no revenue is audited on the same legal footing as a listed one. And there is no activity threshold either. The Department of Business Development requires the annual filing whether the business traded that year or not, so a dormant company still gets audited.

The one exemption: small Thai registered partnerships

The only businesses excused from the audit are small registered partnerships established under Thai law. The DBD's filing manual sets three conditions, and the partnership must satisfy all of them for the financial year:

Exceed any single one and the exemption falls away: a partnership with 4 million baht of capital but 35 million baht of revenue is audited like everyone else.

The exemption is narrower than it looks. It removes the auditor's examination and opinion, nothing more. The partnership still keeps accounts, still prepares financial statements, and still files them with the DBD on the normal deadline. Whether any tax-side sign-off applies to an exempt partnership under the Revenue Code is a separate question with its own history; a firm that handles partnership filings can confirm what currently applies to yours.

No company qualifies, and no foreign entity qualifies. The exemption exists for Thai registered partnerships alone.

Who is allowed to sign the audit

Only a certified public accountant holding a current license can audit financial statements and sign the opinion. Licensing sits with TFAC, the Federation of Accounting Professions, the statutory body created under the Accounting Professions Act B.E. 2547 (2004). TFAC issues, suspends, and revokes CPA licenses, sets the accounting and auditing standards the profession works to, and monitors the conduct of its registrants.

That structure matters more than it first appears. The signature on your audit report is not a formality from a vendor; it is a licensed professional putting their license behind an opinion, under standards and discipline they do not control. It is also why the signature cannot come from your in-house accountant, however qualified. The law reserves it for a licensed auditor acting in that capacity.

The auditor cannot mark their own homework

The Accounting Act splits the work into two roles. The accountant prepares the accounts and is entitled to receive complete supporting documents from the business. The certified auditor then examines what was prepared and gives an opinion on it. Different duties, different people.

That separation is the practical reason your bookkeeping firm should not also be your auditor. An auditor examining ledgers their own colleagues posted would be reviewing their own work, and the opinion loses the independence that gives it value. Reputable firms keep the two engagements apart, and many businesses simply use two unrelated firms: one to keep the books, one to audit them. When you engage an accounting firm for the year, ask early how the audit will be kept separate. The answer tells you a lot about the firm.

What the auditor actually examines

An audit is an evidence exercise, not a re-doing of the bookkeeping. Working to the auditing standards TFAC sets, the auditor tests whether the financial statements fairly reflect the business: they trace balances back to the supporting documents the law requires the business to keep, confirm bank balances directly with the banks, check that revenue and expenses landed in the right period, and look at whether assets on the balance sheet exist and are worth what the statements say.

Expect requests. Bank statements and confirmations, invoices and receipts behind sampled transactions, contracts behind significant balances, stock counts where inventory matters, and written explanations for anything unusual. A business whose documents are organised gets through this in days; one whose documents are scattered pays for the difference in time and fees.

The output is the auditor's report: an opinion on whether the statements present the business fairly. A clean opinion is the normal outcome. A qualified one, flagging something the auditor could not verify or does not agree with, follows the statements wherever they go, which is exactly why banks and counterparties trust audited numbers.

Where the audit fits in the annual chain

The audit is the first link in a fixed sequence, and every later deadline counts from your book-closing date. For a limited company: the audited statements go to the shareholders' annual general meeting for approval within four months of closing, the approved statements are filed with the DBD within one month of that meeting, and the corporate income tax return follows from the same closed books, which the Revenue Department requires within 150 days of the closing date. Registered partnerships, foreign juristic persons, and joint ventures skip the meeting step and file their auditor-examined statements within five months of closing. Miss the audit and every downstream deadline fails with it; what the engagement looks like month by month, and what it costs at each stage, is covered on the statutory audit page.

Choosing an auditor

For most small and mid-sized businesses, the choice is less about brand and more about fit. Three questions do the sorting.

Does the auditor know your kind of business? An auditor who has audited importers, or restaurants, or software companies before will ask for the right documents the first time.

Can they hold your deadline? Audit work in Thailand bunches heavily after the December book-closing that most businesses use. An auditor who takes on more year-ends than they can staff becomes your bottleneck in March.

How do they handle findings? A good auditor raises problems during the engagement, while there is still time to fix them, rather than surprising you in the report. Ask how they communicate along the way.

Fees are quoted per engagement and scale with transaction volume and how clean the records are, so no honest general figure exists. Get quotes against your actual trial balance. The audit services page covers what to compare and what a quote should include.

Audits the law does not require

Not every audit is a statutory one. Businesses commission a financial audit outside the annual cycle when someone specific needs assured numbers: a bank considering a loan, an investor doing due diligence, a buyer pricing an acquisition, or a head office that wants its Thai subsidiary examined against group standards. Same licensed profession, different trigger and scope.

An internal audit is different again: an ongoing review of the company's own controls and processes, reporting to management or the board rather than to the registrar. Thai law does not require one for ordinary private companies, but growing businesses often add one once approval chains and inventory get too big to watch informally.

If you are unsure which of these you actually need, start from who is asking for the numbers. The state asks every year; that is the statutory audit. Anyone else asking is a commissioned engagement with a scope you define.

This guide is general information about audit obligations in Thailand, not accounting, tax, or legal advice. Thresholds, deadlines, and penalties change, and how the rules apply depends on your entity and circumstances. For a specific case, speak with a licensed auditor or a qualified accounting firm.