For a company seller the tax is 1% of the higher of the sale price and the appraised value, and it counts as a credit against the company's corporate income tax.
For an individual the calculation uses the appraised value, not the price. A standard deduction is taken according to the number of calendar years of ownership, from 92% for one year down to 50% for eight years or more. The remainder is divided by the years of ownership, taxed at the progressive personal rates of up to 35%, and multiplied back by the number of years. An individual can generally treat the amount withheld as final tax on the sale.
Thailand has no separate capital gains tax for individuals selling property, so this withholding is how the gain is taxed. It is the seller's cost.
On rental income, 15% is withheld from rent paid from Thailand to a non-resident owner. See property taxes and buying costs and rental income and tax.



