Thailand and your country may have a Double Taxation Treaty which states that income from real estate is taxable in the Contracting State where the property is located. In that case, when buying an apartment or a house in Thailand, it will be Thai taxation only which will apply on Thai rental income. However, if you are a US citizen or if your country does not have such a treaty with Thailand, you will need to check with the competent authorities and lawyers of your home country. Other rules may apply regarding the declaration of foreign income that you will need to take into account.