Thailand: local rules

Thailand's transfer pricing rules are in the Revenue Code, added by Revenue Code Amendment Act (No. 47) B.E. 2561 (2018) for accounting periods starting on or after 1 January 2019. Section 71 bis lets the assessor adjust the income and expenses of related companies whose commercial or financial terms differ from what independent parties would agree, if profit appears to have been shifted. Companies are related if one holds at least 50% of the other, if the same holder has at least 50% in both, or if one cannot act independently of the other because of capital, management or control. Ministerial Regulation No. 369 (B.E. 2563) sets the test, and Director-General Notification (Income Tax) No. 400 (2021) sets the criteria and methods for accounting periods starting on or after 1 January 2021.

A company that has related parties and revenue above THB 200m in the accounting period must file the Disclosure Form (related parties and total transactions with each) with its corporate income tax return, within 150 days after year end (s. 71 ter, Ministerial Regulation No. 370). The duty applies even if there were no transactions. Within 5 years after that filing, the assessor can send a written notice asking for transfer pricing documents. The company has 180 days for the first notice and 60 days for later ones, and the Director-General can extend a 60 day period to at most 120 days (s. 71 ter para 2). Notification No. 407 lists the content (business and organisation, group structure, controlled transactions, pricing method, comparables) and says it must be in Thai. Thailand has no separate master file. Groups with revenue of THB 28bn or more also file a country-by-country report.

The five OECD methods are accepted: comparable uncontrolled price, resale price, cost plus, transactional net margin and transactional profit split (Notification 400, art. 5). The most appropriate method for the case must be used, looking at strengths and weaknesses, functions, assets and risks, data quality and comparability (art. 6). If the result is outside the arm's length range, the assessor can adjust it to a point inside the range (art. 8). Another method may be used only if the five cannot reasonably apply, and the company must tell the Director-General in writing within that accounting period and keep the support ready (art. 5). Intra-group services must be real, useful, something an independent party would pay for, and priced at arm's length; costs for the benefit of ownership are not accepted (art. 9). Bilateral advance pricing agreements can be requested (art. 13).

Not filing the Disclosure Form, not giving the documents asked for under s. 71 ter, or giving incomplete or incorrect information without reasonable cause is a fine of up to THB 200,000 (s. 35 ter). Late payment of corporate income tax brings a surcharge of 1.5% a month on the unpaid tax (Revenue Department PND 50 instructions). An adjustment under s. 71 bis is assessed under the normal Revenue Code rules, and the exact penalty and surcharge rates for adjustments were not checked. The Top-up Tax Decree fines a missing report or return up to THB 200,000 (s. 84), and a deliberate false or missing filing up to one year in prison or THB 500,000 (s. 86).

The Emergency Decree on Top-up Tax B.E. 2567 (2024), published on 26 December 2024, applies to accounting periods that start on or after 1 January 2025. It covers a Thai entity of a group whose consolidated revenue was at least EUR 750m (in baht) in at least two of the four prior periods (s. 26), and it includes the income inclusion rule, the undertaxed payments rule and a domestic top-up tax. A Thai entity must give information on the ultimate parent and the GIR filing entity, file the GloBE Information Return and file the top-up tax return with payment, each within 15 months after the end of the ultimate parent's accounting period (ss. 54, 55, 57). The first accounting period in which the group is subject to the decree gets 18 months instead (s. 58). The GIR can be skipped if the parent or a designated entity files it abroad and a competent authority agreement is in force (s. 56). Thailand has signed the GloBE information return multilateral agreement, and the OECD listed it as a signatory on 8 September 2026.

The corporate income tax return (PND 50) is due 150 days after year end, and companies that file online get 8 more days (158 days) for returns due up to 31 January 2027, unless the Ministry of Finance renews this. Filing dates that fall on a weekend or official holiday move to the next working day for Revenue Code filings under Revenue Department Order Por. 117/2545, which applies section 193/8 of the Civil and Commercial Code. The country-by-country report is due 12 months after year end for a Thai ultimate parent (THB 28bn threshold). Thailand also has a half-year return (PND 51) that this tool does not model.