ORDER OF THE IMMIGRATION BUREAU No. 327/2557
2.18 In the case of being a family member of a Thai national (applicable only to parents, spouse, children, adopted children, or spouse’s children): Each permission shall be granted for no more than one year.
1) The alien must have been granted a non-immigrant visa (NON-IM). (2) The alien must have proof of relationship. (3) In the case of spouse, the relationship must be de jure and de facto: or (4) In the case of children, adopted children, or spouse's children, said children, adopted children, or spouse's children must not be married, must live with the alien as part of the family, and must not be over 20 years of age except in case of the person hereof is of illness or disability and cannot live without support of father or mother: or
5) In the case of parents, the father or mother must maintain an average annual income of no less than Baht 40,000 per month throughout the year or must have deposited funds of no less than Baht 400,000 to cover expenses for one year.