Tax fraud laws in Thailand: penalties, prison risk and how to fix past returns (2026)

Last reviewed: November 2026 · Reviewed by Stéphane Gombauld, tax expert, technologist and digital nomad

You run a business or freelance from Thailand and want to know where honest mistakes end and fraud begins. This guide explains the offences in the Revenue Code, the civil penalties and surcharges, the audit powers of the Revenue Department, the money-laundering link, and how to fix a past return before it becomes a case, all as the rules stand in 2026.

Thailand tax fraud rules in 2026: the key figures

Is this guide for you?

Read on if you…

• file Thai personal or corporate returns and want to understand the penalty ladder before you make a mistake;
• have received a letter, summons or audit notice from the Revenue Department;
• have unreported remittances or an unregistered business and want to regularise.

Probably not your case if you…

• are a non-resident with no Thai income or assets (no Thai filing, no Thai exposure);
• are looking for customs or excise offences (different acts, different authorities).

What counts as tax fraud under Thai law?

The Revenue Code (Pramuan Rasdakorn) separates careless under-payment from fraud, which requires intent. The main criminal provisions:

• Section 37(1): knowingly giving false information, false evidence or false statements to evade tax.
• Section 37(2): evading or attempting to evade tax by fraud, deceit or similar means.
• Section 37 bis: deliberately not filing a return in order to evade tax.
• Section 90/4: VAT-specific fraud, including issuing or using fake tax invoices and claiming refunds you are not entitled to.

Typical fact patterns in 2026 cases: a Thai company booking fake supplier invoices, a freelancer running a business through personal accounts and never registering, a landlord hiding rental income, and foreigners remitting post-2024 foreign income with no return. The last one is new ground: the rule changed in 2024 and the Revenue Department has said it will use bank and exchange-of-information data to check remittances.

Intent is the hinge. Forgetting a deadline is Section 35, a THB 2,000 fine. Structuring your affairs to hide income is Section 37. Between the two sits the civil regime, which does not need intent at all.

How much do civil penalties and surcharges cost?

Most people never see a criminal court. They meet the assessment officer. After an audit, three amounts stack:

1. The tax itself, recomputed.
2. A penalty (bia prap) of 100% of the shortfall if you filed but under-declared, or 200% if you never filed (Sections 22 and 26). For VAT the penalty is generally 100%, rising to 200% for a missing return (Section 89).
3. A surcharge (ngern perm) of 1.5% per month from the due date, capped at the amount of tax (Section 27). It is interest by another name and is never waived.

Penalties can be reduced. Under Ministerial Regulation No. 134 (or the Director-General's notice that applies in your case), the officer can cut the penalty to 50% or less when you cooperate and file within the deadline set in the audit notice. The surcharge stays.

Example of the arithmetic: THB 500,000 of under-declared corporate tax, found three years late. Penalty THB 500,000, surcharge THB 270,000 (36 months × 1.5%). Total bill THB 1.27 million, before any criminal referral.

What powers does the Revenue Department have?

Under Sections 19 and 23 of the Revenue Code, an assessment officer can summon you, your accountant and third parties, demand books and documents, and assess on an estimated basis if you do not produce them. Specific tools in 2026:

• Bank data. Under the 2019 amendment to Section 3 sexdecies, banks must report accounts with 3,000 or more incoming transactions a year, or 400 or more transactions totalling THB 2 million or more. This is how unregistered online sellers and freelancers are found.
• Exchange of information. Thailand joined the Common Reporting Standard and exchanged data for the first time in 2023. Your foreign bank balances are visible to the Revenue Department. See tax treaties of Thailand.
• E-withholding and e-tax invoice data. Mismatches between what your clients withheld and what you declared trigger letters automatically.
• Time limits. The officer has two years from the filing date to issue a summons, five years with the Director-General's approval where evasion is suspected, and ten years where no return was filed (Sections 19 and 23).

Enforcement starts with a polite letter inviting you to "check your filing". Answer it. Silence leads to an estimated assessment with the full 200% penalty.

When does tax fraud become money laundering?

Since 2017, Section 37 ter of the Revenue Code makes serious tax evasion a predicate offence under the Anti-Money Laundering Act. The thresholds:

• evasion of THB 10 million or more of tax in a single tax year, or
• a fraudulent VAT refund of THB 2 million or more,

in both cases involving false documents or fraudulent means. Once the Revenue Department's committee refers a case, the Anti-Money Laundering Office (AMLO) can freeze and seize assets, including property and bank accounts, before any conviction. Thailand is also a member of the Asia/Pacific Group on Money Laundering, so foreign authorities can request the same measures.

For a one-person business this threshold is far away. For a founder running a THB 100 million company through the wrong structure, it is not. Choosing the right entity matters; see legal forms of business in Thailand.

How do you fix a past return before it becomes a case?

Thailand has no formal voluntary disclosure programme in 2026, but the mechanics reward coming forward:

1. File an additional or amended return (P.N.D. 90/91 for individuals, P.N.D. 50 for companies) for each open year, before you receive a summons. Penalties under Sections 22 and 26 apply to assessments; a self-filed amendment triggers only the surcharge in most cases.
2. Pay the tax and the 1.5% monthly surcharge at filing. Instalments over up to three months are possible for personal income tax above THB 3,000.
3. Register for VAT retroactively if your turnover passed THB 1.8 million. Late registration carries a penalty of twice the tax due and the surcharge, but it is cheaper than being found.
4. Keep the evidence. Bank statements, invoices, and for remittances the proof of when the foreign income arose and whether you were resident that year.
5. Ask for a penalty reduction in writing if an audit is already open; cooperation is the main criterion.

For criminal exposure, the Revenue Department can compound (settle) many offences by payment of a fine under Section 3 bis, avoiding court. Section 37 cases that have been referred to the police are a different matter: get a Thai lawyer, not just an accountant.

Common mistakes (and what they cost)

• Treating "foreign income is tax-free" as still true after 2024 → remitted income assessed with 200% penalty if no return was filed.
• Running a business through a personal bank account → bank transaction reports flag you; VAT and income tax assessed with penalties for every open year.
• Using a nominee or a friend's account to receive money → converts an under-payment into Section 37 fraud with prison exposure.
• Ignoring the first letter → estimated assessment, penalty at the maximum, assets at risk of seizure.
• Backdating or "recreating" invoices during an audit → false evidence under Section 37(1), and for VAT, Section 90/4.

Frequently asked questions

Can you go to prison for tax evasion in Thailand?

Yes. Section 37 of the Revenue Code provides three months to seven years' imprisonment plus a fine of THB 2,000 to 200,000 for fraudulent evasion. In practice most cases end with a settlement fine and payment of tax, penalty and surcharge. Prison sentences are reserved for organised fake-invoice schemes and large, deliberate evasion.

What is the penalty for filing a Thai tax return late?

A fine of up to THB 2,000 under Section 35, plus a surcharge of 1.5% per month on any tax due. If you file after an assessment officer has already found the omission, the penalty is 100% of the tax, or 200% if no return had been filed at all. Filing late is far cheaper than being found.

How far back can the Revenue Department audit me?

Two years from the date you filed, extendable to five years with the Director-General's approval where evasion is suspected. If you never filed a return for a year, the limit is ten years. Keep your records for at least five years; companies must keep accounts for five years under the Accounting Act.

Does the Revenue Department know about my foreign accounts?

Increasingly, yes. Thailand exchanges financial account data under the Common Reporting Standard since 2023, receives FATCA-related data from the United States, and collects Thai bank transaction reports above the 3,000-transaction or THB 2 million thresholds. Assume the data exists and file accordingly.

Is there a voluntary disclosure programme in Thailand?

Not a formal one in 2026. The practical route is to file additional returns for each open year and pay the tax with the 1.5% monthly surcharge. Amending before a summons generally avoids the 100% or 200% penalty. Occasional amnesty measures have been offered for companies in the past; none is open for individuals in 2026.

What happens to a company director?

Under Section 37 and the Accounting Act, directors who order or knowingly allow false accounts face personal criminal liability. The company pays the tax, penalty and surcharge; the director can be fined or imprisoned personally. Compare with how directors are treated in the tax fraud regulations of Singapore and Hong Kong.

Related guides

• Your tax guide to Thailand
• Personal income taxes in Thailand
• Corporate income tax in Thailand
• Tax residency in Thailand
• Tax treaties of Thailand and information exchange
• Legal forms of business in Thailand
• Tax fraud regulations of Singapore
• All country tax guides

Sources

• The Revenue Department of Thailand – English portal
• Office of the Council of State – Thai legislation (Revenue Code, Anti-Money Laundering Act)
• Anti-Money Laundering Office (AMLO), Thailand
• Royal Thai Government Gazette
• OECD – Automatic exchange of information portal

This guide is general information, not personalised tax advice. See how we research and review.