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Service guide
Corporate Tax Filing in Thailand.
Corporate tax filing in Thailand: the annual PND 50 due within 150 days of year end, the half-year PND 51, audited accounts, and what a filing firm handles.
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Key facts
- When is the annual corporate tax return due?
- The annual return, PND 50, is due within 150 days of the closing date of the company's accounting period. For a December year end that window runs to late May.
- What is the half-year return?
- The PND 51. Companies pay half of the estimated tax for the year within two months after the end of the first six months of the accounting period, and the payment is credited against the annual liability.
- Who has to file?
- Thai and foreign companies carrying on business in Thailand are required to file corporate income tax returns with the Revenue Department, whether or not the year ends in a profit.
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Corporate tax filing in Thailand: the calendar
Corporate tax filing in Thailand runs on two fixed returns. Thai and foreign companies carrying on business in Thailand are required to file returns with the Revenue Department: the annual return, PND 50 (the form the Revenue Department's English materials call CIT 50), is due within 150 days of the closing date of the accounting period, and the half-year return, PND 51, pays half of the estimated tax for the year within two months after the end of the first six months of the accounting period.
The annual return reconciles the year's real result against what was paid at half year. Behind it sit the company's financial statements, which in practice are audited as part of the annual close for Thai companies; audit firms handle that work, and the return and the audited numbers need to agree.
Miss a deadline and the Revenue Code attaches surcharges and fines. The exact amounts depend on the return and the delay, so a firm confirms them for a specific case rather than a page quoting a single number.
The two corporate income tax returns
Filing deadlines published by the Revenue Department. The half-year payment is based on estimated full-year profit and is credited against the annual liability.
| Form | Deadline | |
|---|---|---|
| Annual return | PND 50 (CIT 50) | Within 150 days of the closing date of the accounting period |
| Half-year return | PND 51 (CIT 51) | Within two months after the end of the first six months of the accounting period, paying half of the estimated tax |
- Annual return
- Form: PND 50 (CIT 50)
- Deadline: Within 150 days of the closing date of the accounting period
- Half-year return
- Form: PND 51 (CIT 51)
- Deadline: Within two months after the end of the first six months of the accounting period, paying half of the estimated tax
Source: Revenue Department, Corporate Income Tax
Checked August 2026
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What a filing engagement covers month to month
A filing engagement is steady work, not a once-a-year scramble. Through the year the firm keeps the books current, usually alongside the company's accounting function, so the numbers the returns need already exist when the deadlines arrive.
Mid-year, the firm prepares the PND 51: it builds the full-year profit estimate from the first six months, calculates half the estimated tax, and files and pays on time. At year end it moves to the annual cycle: closing the books, coordinating with the auditors, preparing the PND 50 from the audited figures, and filing within the 150-day window.
What filing does not include is the judgment layer: whether the company's structure, deductions, and incentives are set up well in the first place. That is corporate tax planning, a separate engagement, and a company whose position is complicated usually needs both.
One filing year, in order
Keep the books filing-ready
Monthly bookkeeping and reconciliations run through the year. Returns built on messy books are late returns; most deadline trouble starts here, not at the form.
File the half-year PND 51
Within two months after the first six months of the accounting period, the firm files the PND 51 and pays half of the estimated tax for the year, keeping the reasoning behind the estimate on file.
Close the year and coordinate the audit
After period end the firm closes the books and works with the auditors so the financial statements and the tax computation tell the same story.
File the annual PND 50
The annual return is prepared from the final figures, credited with the half-year payment, and filed within 150 days of the accounting period's closing date, with the workpapers kept for any later Revenue Department questions.
When to hand filing to a firm
A company with any real activity rarely saves money doing this in-house without a Thai accountant. The forms are in Thai, the deadlines do not move, and the cost of getting the half-year estimate or the annual reconciliation wrong lands later, with interest. Firms price filing as a recurring engagement, so compare what the monthly scope includes rather than the headline fee, and involve tax lawyers in Thailand when a filing position is disputed rather than merely due.
This page is general information, not legal advice. Deadlines, rules, and procedures change; for a specific company, speak with a qualified professional.
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Common questions
Frequently asked questions
- When is corporate tax filing due in Thailand?
- Two returns fix the calendar. The half-year return, PND 51, is due within two months after the end of the first six months of the accounting period and pays half of the estimated tax for the year. The annual return, PND 50, is due within 150 days of the closing date of the accounting period and settles the real result, credited with the half-year payment.
- Does the annual corporate tax return need audited financial statements?
- In practice the annual close for Thai companies includes audited financial statements, and the PND 50 is prepared so the tax computation and the audited figures agree. The audit itself is separate work done by a licensed auditor, and an audit firm confirms the exact statement and submission requirements for a specific company.
- What happens if a company files its Thai tax return late?
- Late filing and late payment attract surcharges and fines under the Revenue Code, and the amounts grow with the delay. The Revenue Department's published English materials do not put a single figure on every case, so a firm confirms the exact exposure for a specific return before deciding how to fix a missed deadline.
- What does a corporate tax filing engagement include?
- Typically: keeping the books filing-ready through the year, preparing and filing the half-year PND 51 with a documented profit estimate, closing the year and coordinating with the auditors, and preparing and filing the annual PND 50 within the 150-day window. Advisory work on structure, deductions, and incentives is a separate planning engagement.
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Accounting firmBangkokThai · English · French
Cloud-based accounting, tax filing & payroll for businesses in Thailand. All-inclusive pricing, zero hidden fees, 24/7 online access.
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Experts assisting clients in conducting their businesses and protecting their rights and investments in Thailand across a wide range of legal matters.
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