There is no precise doctrine of piercing the corporate veil in Thai law.
Generally, a company always has a limited liability up to the value of the registered shares of the company. The persons behind the corporate veil normally escape from their liabilities, but under this doctrine, such persons are held liable in lieu of the company.
However, there are some parts of Thai law compatible with this doctrine.
For instance, the agency law under the Thai Civil and Commercial Code.
The Consumer Protection Procedure Law also allows an injured party to demand the authorized directors of a company take personal liability.