Previously, it became automatic and compulsory on the part of the illegitimate child to carry the surname of his/her illegitimate father whenever he/she will be acknowledged. However, the Supreme Court struck down the NSO's rules regarding the matter in GRACE M. GRANDE v. PATRICIO T. ANTONIO, G.R. NO. 206248, February 18, 2014. The Supreme Court held that Art. 176 of the Family Code gives illegitimate children the right to decide if they want to use the surname of their father or not. On its face, Art. 176, as amended, is free from ambiguity. And where there is no ambiguity, one must abide by its words. The use of the word “may” in the provision readily shows that an acknowledged illegitimate child is under no compulsion to use the surname of his illegitimate father. The word “may” is permissive and operates to confer discretion upon the illegitimate children.
With that in mind, if you do plan to acknowledge your illegitimate child, your child cannot yet take on your surname, when the time comes, your child will have to decide if he/she will use your surname.