Under current legislation, a foreigner can not own land in Thailand. Land management is possible a number of different ownership structures. Here are the most common:
1. Manage through by the Thai company the most popular and safest options. You can own your company's shares 49% and the remaining 51% is usually divided into two Thai Shareholder.
2. The leasehold is one of the options used, but land authority currently accepts only a 30-year lease. In this option your investment is only secured for next 30 years. Under this option, you should very carefully and think what you are going to do to investment in the future, simply because the leasehold properties can be very difficult to sale.
Foreign quota is limited to 49%, which means that the complex of the condominium 49% can be directly owned by foreigner and the remaining 51% must be in Thai or Thai Co. ownership. Ask more information from your realtor.