If you are earning in Thailand, then you must have your own tax ID number. You can get it from the tax office. Just make sure you present your ID, including your passport or ID card. Additionally, you will need to prove why you require the number. And those who have been living in Thailand for more than 6 months may have similar tax obligations like Thais. In that case, you will be expected to pay taxes on all your income, earning worldwide. On the other hand, if you are in the country for 180 days or less, then you are to pay tax on only the income coming within Thailand. For your information, having a working permit or not has nothing to do with paying taxes.
Incomes that are assessable usually come under Personal Income Tax, including non-cash payments like the use of the car(s), and accommodation. However, there are other categories of personal income as well, such as income from a position, dividends, income from construction work, income from a business, income from royalties, income from employment, and income from rental agreements.
Well then, there are many deductions that can be made from the assessable income and that should be in an order. An individual who is completing a tax return in Thailand should begin with the assessable income amount and then take away the deductions like expenses and personal allowances. And the amount left is the one that is taxed. However, there are different percentage deductions based on the type.
But then, if your earning is lesser than 150,000 Baht, then you are exempted from income tax and anything more than this or lesser than 500,000 THB is taxed at 10%, whereas earnings between 500,000 THB and 1 million is taxed at 20% rate. If your earning is below 4 million THB but more than 1 million then you will be taxed at 30% and anything more than this amount is taxed at 37%.
