Double tax agreements and residence certificates

Yes. Employment duties performed in Thailand are Thai-source income under section 41, even where the employer sits abroad and pays into an offshore account. This is the key point for remote workers and should be read together with the double tax agreement with the payer's country, and separately from work-permit law, which is a different statute with its own requirements.

Three layers decide it. First, whether you are a Thai resident in that tax year. Second, when the pension income arose and when it was brought in. Third, what the double tax agreement between Thailand and the paying country says about pensions. Many treaties give exclusive taxing rights over government-service pensions to the paying state, while private pensions may fall to the residence state. The applicable treaty must be read case by case.

The payer must issue this certificate to the recipient whenever tax is withheld, stating the income category, the gross amount and the tax withheld. The recipient uses it as a tax credit on the annual return. Without it, claiming the credit or a refund becomes difficult, so request and file the certificate at the time of payment rather than at year end.

In business practice, service fees and contract work are commonly withheld at 3%, rental of immovable property at 5%, advertising at 2%, and professional fees at 3% where the recipient is a Thai company. Salaries are withheld on an annualised computation. Payments to recipients abroad carry their own rates and may be reduced under a double tax agreement. The correct rate depends on the income category and the recipient's status — check the relevant Revenue instruction before withholding.

Thailand's double tax agreements allocate taxing rights over each class of income — employment, business profits, dividends, interest, royalties and pensions — between Thailand and the treaty partner, and set out the relief mechanism, usually a credit for tax paid in the other state. To rely on a treaty you must prove tax residence and usually file the form the treaty partner prescribes.

Apply to the Revenue Department for the certificate of residence, known by its form reference R.O.22, showing that you met the day threshold in the year concerned — stamped passport pages, proof of address, and evidence of Thai filings and tax paid. Foreign tax authorities use it to grant treaty relief. The companion document, R.O.21, certifies the Thai tax actually paid.

Not automatically. If the income is within the Thai net, it is generally included in the Thai computation and you then claim a credit for foreign tax as permitted by the applicable treaty and Revenue Department practice. The credit is usually capped at the Thai tax attributable to that income, so prepare foreign tax receipts with certified translations in advance.

Thailand has double tax agreements in force with more than 60 partner jurisdictions, covering its main trading partners and the countries whose nationals most commonly live in Thailand, including the United States, United Kingdom, Australia, Germany, France, Japan, South Korea, China and Singapore. The list and the operative texts are published by the Revenue Department; always read the specific treaty because the articles differ between them.

Thailand has DTAs with over 60 countries. They allocate taxing rights by income type and allow foreign tax paid to be credited against Thai tax within limits. The core document is a Certificate of Residence from the treaty partner, plus proof of foreign tax paid and a certified Thai or English translation. The Revenue Department sometimes asks for legalized documents; from 28 February 2027 an Apostille from a Convention country will replace the two-step legalization chain.

File form L.P.10.1 at the Area Revenue Branch Office for your residence with your passport, current visa and latest entry stamp, work permit or evidence of income, and proof of address such as a lease, house book or TM.30 receipt. The number is normally issued the same day at no charge. A TIN is required to file PND.90/91, reclaim withholding tax and apply for the R.O.22 certificate of tax residence.

Apply at the Large Taxpayer Office or the Area Revenue Office where you file, showing at least 180 days of presence in the tax year and that you have filed your return. Foreign tax authorities accept it to grant treaty withholding rates on dividends, interest and royalties. Processing typically takes 15–30 working days, and the certificate usually needs certified translation before use abroad.

Under Section 70, certain payments to a foreign company not carrying on business in Thailand require withholding and remittance on form PND.54 by the 7th of the following month. Standard rates are 15% for interest and royalties and 10% for dividends, though a DTA may reduce them if the recipient supplies a certificate of residence before payment. Service fees used in Thailand may also trigger self-assessed VAT on form PP.36.

Registration is mandatory once taxable turnover exceeds THB 1.8 million per year; file PP.01 within 30 days of crossing the threshold. Voluntary registration is available below it if you want input tax credits. Registered businesses must issue full tax invoices under Section 86/4, keep input and output VAT reports, and file PP.30 with payment by the 15th of the following month, extended by eight further days for online filing.

Apply at the responsible Area Revenue Office or the Large Business Tax Administration Division with a copy of the filed PND return and its receipt, passport copies showing entry stamps for the whole tax year, and documents for the income you want treaty relief on. Processing depends on file completeness and office workload — count in weeks, not days. Allow time before the destination country's own deadline.

R.O.21 is a Tax Payment Certificate proving tax was actually paid in Thailand for a stated amount and year, used when the other country needs evidence to grant a foreign tax credit. R.O.22 is a Certificate of Residence proving your tax residence status for treaty purposes. Many claims require both documents together.

It depends on two things: whether you were present 180 days or more in the tax year, and whether the pension was remitted into Thailand. If both apply, it enters the Thai computation under the applicable rules. However, several treaties assign the exclusive right to tax government-service pensions to the source country, so read the specific treaty and prepare a residence certificate to claim the relief.

Thailand has treaties with more than sixty countries. They allocate taxing rights by income type and allow a credit for foreign tax against Thai tax on the same income, capped at the Thai tax on that income. Claims need a certificate of tax residence from the other state and evidence of tax paid, and some reliefs must be claimed before payment rather than after.

It certifies Thai tax residence so a foreign tax authority will apply treaty rates instead of full domestic withholding. It is applied for at the Revenue Department with proof of presence, filed returns and income documents, and it is normally paired with an R.O.21 confirming tax actually paid in Thailand. Allow several weeks, so apply before the foreign deadline, not after it.

Typically the Revenue Department application form, a passport copy with entry and exit stamps showing 180 days or more in Thailand in that tax year, the filed income tax return with payment receipt, and evidence of the income you want to claim treaty relief on. A representative needs a power of attorney with duty stamps, and foreign documents need certified translation. We assemble the file and follow up with the office for you.

It evidences to a foreign tax authority that tax was paid in Thailand so you can claim a credit or refund there. Apply at the area revenue office that receives your return, attaching proof of remittance, withholding certificates from the payer and the underlying contracts. Allow extra time if the receiving country wants an English version or legalisation.

If you spend 180 days or more in Thailand in a tax year you are tax resident, and income from work performed in Thailand is Thai-source under Section 41, so a return is due even though the payer is abroad. Where tax was already withheld at source, check the relevant double tax agreement for a credit or exemption, and keep the employment contract, transfer records and entry/exit history.

Consider Section 70 together with the applicable treaty. Where the payment is a royalty or service fee falling under Sections 40(2) to 40(8), the Thai payer must withhold and remit using form PND.54, and self-assess VAT on form PP.36 where applicable. To apply a reduced treaty rate, keep the counterparty's certificate of tax residence on file.

Our advisers have worked on cross-border documentation for more than 15 years. We analyse tax residence, build the evidence file for each income source, obtain R.O.21 and R.O.22, translate and legalise documents, file returns and follow up with the area revenue office, and bring in a licensed accountant when the case needs a formal opinion. Contact us for a case assessment before any work starts.