For foreigners wishing to extend their stay in Thailand, in the case of being family members of a Thai national (only parents, spouses, children, adopted children, or children of spouses), the Immigration Office has determined the requirements, as follows:

1. They must hold a non-immigrant visa;
2. Proof of relationship is required;
3. In the case of a spouse, they must have a legal and de facto relationship; or
4. In the case of a child, adopted child, or spouse's child requesting patronage of such child, adopted child, or spouse's child, they must not be married, must live as part of that household, and must not be over 20 years of age; or
5. In the case of a father or mother, he or she must have an annual average income of not less than 40,000 baht per month or a deposit of not less than 400,000 baht for spending in a year;
6. In the case of marriage with a Thai woman, the foreign husband must have an average annual income of not less than 40,000 baht per month or a balance of not less than 400,000 baht for spending in a year in a bank account in Thailand for the past 2 months. 

     Other supporting documents are required for the cases of sponsoring a Thai child, a Thai wife, or a Thai husband. 

     The applicant and his/her child/wife/husband who are Thai nationals must show up in person to give evidence and present the original documents and certified copies with the applicant’s signature.