Keeping track of Thailand’s various tax deadlines is considerably easier with them all in one place, worth bookmarking this as your annual reference rather than tracking each obligation separately.

Personal income tax: the big annual deadline

Your annual personal income tax return, Form PND.91 for employment income or PND.90 for other income types, is due **31 March** for paper filing, extended to **8 April** if you file online through the Revenue Department’s e-filing system. This covers the previous calendar year’s income, for income earned in 2025, your filing deadline falls in early 2026. This is the deadline that applies most broadly, covering employees, retirees with assessable income, and anyone with foreign income remitted into Thailand during the year.

VAT: a monthly rhythm, not an annual one

If your business is VAT-registered, returns (Form PP.30) are due **every single month**, by the **15th** for paper filing or the **23rd** for electronic filing. This applies even in months with zero taxable sales, a blank return is still required. Missing six consecutive monthly filings triggers automatic deregistration, making this genuinely worth building into a recurring calendar reminder rather than an occasional task.

Corporate income tax: two filings per year

Companies face two separate corporate tax filings each year. The half-year return (Form PND.51), based on estimated annual profits, is filed roughly midway through your accounting period. The annual return (Form PND.50) is due within **150 days** of your accounting period’s end, for a standard 31 December year-end, this typically means a deadline around **30 May** the following year.

Employer withholding tax: monthly, ongoing

If you employ staff, monthly withholding tax returns (Form PND.1), covering tax withheld from employee salaries, are due by the **7th of the following month**. This is a continuous employer obligation running throughout the year, alongside your own personal filing and any corporate obligations your business separately faces.

90-day address reporting: a different kind of deadline

Separate from tax filing entirely, but worth including here since it shares similar calendar-tracking discipline, your 90-day immigration address report has its own recurring deadline, fileable from 15 days before your due date to 7 days after. This isn’t a Revenue Department obligation, but it’s exactly the kind of recurring compliance task worth tracking alongside your tax calendar for the same reason: missing it is entirely avoidable with a bit of planning.

When deadlines shift

If any of these dates falls on a weekend or public holiday, the deadline moves to the next business day. It’s worth checking the exact date each year rather than assuming a fixed calendar date applies consistently, since this shift means the practical deadline can vary by a day or two from year to year.

What happens if you miss one

Penalties vary by filing type but typically follow a similar pattern: a flat fine for late submission, plus a 1.5% monthly interest charge on any unpaid tax, with more serious penalties for deliberate non-compliance or discovered under-reporting. Across every filing type, filing late is consistently better than not filing at all, penalties for genuine non-filing are considerably more severe than those for a late but honest filing.

A simple system worth adopting

Rather than tracking each deadline separately in your head, most residents find it works well to set calendar reminders roughly two to three weeks ahead of each recurring deadline, personal filing in March, VAT monthly if applicable, corporate filings if you own a business, and 90-day reporting on its own cycle. This buffer gives you genuine room to gather documentation or address any gaps before the actual deadline arrives.

Final thoughts

None of Thailand’s tax deadlines are individually complicated, but keeping them all straight, particularly if you’re managing personal filing, VAT, and employer obligations simultaneously, benefits genuinely from having them consolidated in one place and reviewed annually, since specific dates can shift slightly year to year around weekends and holidays.

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