How to file personal income tax return in Thailand & pay your tax

Compared to other countries, such as the UK or the USA, filing a personal tax return in Thailand is surprisingly easy. It only takes a few minutes (provided you have been doing the calculations using the Thailand tax calculator). Even if you haven’t, it’s still a relatively straightforward process that consists of three basic steps:

1. Preparing your information & documents (incl. calculating your tax)
2. Choosing your preferred filing method
3. Filing your tax return & paying tax (or getting a refund)

Two main types of tax returns/forms in Thailand – PND 90/91

Depending on what income you earn, you will have to file one of the following tax returns:

Refer to the personal income tax overview to learn about the different types of income.

If you are filing a joint filing with your spouse, you will need to attach a respective joint filing with one of the above forms.

Preparing your information & documents for filing

You will only need a couple of numbers and documents to get started. Let’s start with the documents. You will need:

Required documents

• Tax ID (you got it when you first started working as all employees need to have one)
• Employer’s taxpayer identification number
• Withholding tax certificates (the Revenue Department usually requests these in case of a tax refund)
  • Form BIS 50 provided by your employer if you are employed (or invoices if self-employed)
  • Certificate of Personal Health Insurance Premium for Income Tax Deduction from the health insurance company
  • From your banks, if you have savings accounts
  • Other certificates for other deductions such as life insurance

Other documents might be required based on your situation, but those listed above should be sufficient for most.

Now onto the numbers. If you haven’t calculated them yet, I recommend first downloading the tax calculator and going through the instructions on filling it in. Once you are done, you will be using the following numbers from the calculator:

Required totals

• Total income (employment and all other sources of income combined)
• Withholding tax
• Social security contributions
• Deductions & allowances (depends on your scenario, see all available deductions & allowances)

Where and when to file a personal income tax return in Thailand

Once you have calculated your tax with the tax calculator and collected all the documents, you have four options for filing your tax return in Thailand.

1. Let your employer do it for you

When to file: April 8 each year for online or March 31 for offline filing

This is the easiest way for most, but not necessarily the best as you have the least control over the input. Most companies do this for their employees automatically. The HR staff usually handles the process and requires little to no effort from your side.

If you want maximum control over your finances and file your return yourself, the following options are for you.

2. The RD e-filing website (best for expats)

When to file: April 8 each year

The official government website is only in Thai, but it’s pretty easy to use by non-speakers by using the “Translate into English” feature in Google Chrome/MS Edge or other browsers. They have recently redesigned their website, and the experience is quite good.

Besides the ability to file your return, you will be able to view your previous filings and receipts on the website. You will need those documents later when, for example, renewing your work permit.

Visit website

3. The RD SmartTax app (best for Thais)

When to file: April 8 each year

This used to be the easiest and foreigner-friendly way to file your personal income tax return, but they redesigned it in 2021, and now it’s only in Thai. It’s available for iOS and Android and was reliable in the past.

The app and the website are essentially just two different interfaces of the same system, and they will most likely be the two resources you will use most. I used to use the app for filing, but since it’s only in Thai, I switched to using the website for everything instead.

Visit website / Download app

4. Paper filing (the fallback method)

When to file: March 31 each year

You can also file your tax the old-fashioned way by dropping it in paper at any Area Revenue Branch Office. Alternatively, If you live in Bangkok, you can also mail it in together with the check or money order for the total tax due.

This manual method becomes the only way to file your tax once you miss the online filing deadline, so try not to miss it!

Download forms

Overview of the four methods for filing your tax

Filing your tax return using the RD website: Step-by-step example

With your numbers and supporting documents ready, you can now file your tax return. I will use the website to break down the individual steps and demonstrate the process.

If you have never used the RD website, you will first have to create an account where login credentials are your tax ID and the chosen password.

Congratulations, you have successfully filed your tax return!

You will have either overpaid, underpaid or paid your tax precisely. Because the last outcome is rare, I will quickly go through how to deal with the first two scenarios.

Underpaid tax: Paying off your remaining tax balance

In case of a positive balance (meaning you have underpaid your tax), you will have to pay off the rest of your tax bill. The deadline for your payment is stated on the summary page. It used to be a few months away, but now it’s earlier. Below the summary, the website/app then offers multiple ways to pay the remaining tax due. Those are:

• Card
• Money order
• ATM
• Telebanking
• Internet banking
• Mobile banking
• Counter service/pay at the post

Paying your tax in instalments

If your tax due is over 3,000 THB, you can request to pay it in three equal instalments:

If you miss any due date, you will rob yourself of this possibility in the future. You will also need to pay off the remaining balance with a surcharge.

Penalty for late payment (and filing)

If you miss the payment deadline, you will be charged a surcharge of 1.5% of your total tax bill per month. They may also give you a criminal fine of up to 2,000 THB on top of that.

Overpaid tax: Getting a personal income tax refund

If you have overpaid, you will get your money back in the form of a tax refund. You will need to keep an eye on the website/app to see any messages from the Revenue Department. Usually, when you are owed money, the RD will ask for your supporting documents (that’s why you need to have them ready). You can then upload and submit these through the apps for their check. If everything adds up, you will receive your refund.

The rules around getting the tax refund change seemingly every year, so the actual refund payment method will vary. In 2020, for example, the government was returning money via a Bangkok Bank cash card. In 2021, they just mailed a check that can be cashed in your bank.

It usually takes a few weeks to months to receive your money back, so it’s best to estimate your tax and not overpay.

Correcting a mistake in your tax filing

Mistakes happen, but fortunately, it’s easy to fix them. You must go through the whole process again and resubmit your tax return. Like I said above, if you rely on online filing and only notice a mistake after the deadline is over, you will have to file your return on paper. This happened to me in 2021, and a quick trip to my local RD office did the trick. The Revenue Department will be notified of your resubmission and will update your status on the website/app accordingly.