Aliens who wish to apply for Thai nationality under the Nationality Act B.E. 2508 (A.D. 1965) a person does NOT need to be 40 years or have spent 10 years in Thailand.
They must be of the age of majority, be of good character, be gainfully employed, have continuously lived in Thailand for not less than FIVE years and have knowledge of the Thai language. Even though the spouse of a Thai national is a citizen of a foreign country, he/she can apply for the Thai nationality to the Embassy of Thailand. All relevant documents attached to the application must be certified by designated authorities. Documents issued by the Government of a foreign country are to be examined and certified by designated authorities.If the document is in a foreign language besides English, it must be translated into Thai, then examined and certified by the designated authorities. If any of the attached document is a copy, it must be certified as true copy by the designated authorities.