If you bring it to Thailand in a year that you aren't a tax resident, then its non assesable. If its from cash in the bank that was held prior to
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/24 again its non assesable. Pretty much everything else is treated as assesable income, and if your country has a DTA (the country where the money is transfered from), you can use tax already paid as a credit to negate the tax owed in Thailand. Beware of becoming a tax resident, then making a capital again abroad and then remiting the money, as there maybe more tax owed than tax previously paid ddpending on your countries tax rules.