Children: birth registration, who gets Thai nationality, and legitimation by fathers

Every birth in Thailand must be notified to the local registrar within 15 days (a home birth is notified by the householder or a parent; late notification carries a fine of up to 1,000 baht). The child gets a Thai birth certificate whoever the parents are — but a birth certificate is not citizenship. Under the Nationality Act B.E. 2508 (1965) s. 7, a child acquires Thai nationality by birth if the father or the mother is Thai, whether born inside or outside Thailand; since the 2008 amendment 'father' includes a biological father who never married the mother, once fatherhood is proved under the ministerial procedure. Conversely, under s. 7 bis a child born in Thailand to two foreign parents who are here on temporary or irregular status does not acquire Thai nationality — being born on Thai soil is not enough.

For unmarried parents, the mother is automatically the legal parent (CCC s. 1546). The father becomes the legal father only in one of three ways: by later marrying the mother, by registering legitimation (jod tabien rap-rong but) at any district office — which requires the consent of both the child and the mother, with a court judgment substituting if either cannot or will not consent — or by court judgment establishing paternity (s. 1547). Registration is free, and legitimation takes effect back to the child's date of birth (s. 1557), which matters for inheritance and for passing Thai nationality.