In general, dividend, interest, and rental income from local sources by residents and non-residents are taxable income in Thailand.
Interest earned on savings deposits with a bank in Thailand (which are repayable on demand) is tax-exempt if the interest is below a maximum limit of THB20,000 per year.
A resident of Thailand may elect not to include dividend income in his/her annual tax return provided that a tax credit /refund on dividend are not requested.
Interest, dividend, and rental income derived from sources outside Thailand by resident of Thailand are taxable in Thailand to the extent such income is paid or remitted into Thailand within the same calendar year it is received. Non-resident is not subject to Thai tax on such income from foreign-sourced, in any case.