Nonmarital children are those born out of wedlock. Since their parents are not married, they cannot use the surname of their biological father. In one case, the parties had a child prior to getting married. The child used the surname of the father as registered in his birth certificate. Subsequently, the parties tied the knot. Their marriage, however, was later declared null and void in view of a technical legal infirmity. The mother then decided to adopt their child to legitimize his status. Coupled with that was an application for a change of name, to drop the surname of the father. The reason was that since their marriage was declared null and void, their child lost the status of a marital child. Not being one, he could no longer use his father’s surname.

Under the Family Code, if a marriage is declared null and void, the children of that marriage consequently become illegitimate, unless the ground for said declaration is psychological incapacity. The trial court, however, denied the adoption petition and the change of name on the grounds that the biological father refused to give his consent. The father’s opposition was based mainly on the reason that the mother wanted to sever his relationship with his child.

On appeal, the Court of Appeals upheld the denial of the adoption but allowed the change of name. The issue of whether the surname of the biological father can be used by a nonmarital child thus arose. On this issue, the Supreme Court said yes. For as long as there is express recognition of a nonmarital child by the biological father, the former can use his surname.

“Article 176 of the Family Code, as amended by Republic Act 9255, provides guidance on the use of surname by a nonmarital child: Article 176. Illegitimate children shall use the surname and shall be under the parental authority of their mother, and shall be entitled to support in conformity with this Code. However, illegitimate children may use the surname of their father if their filiation has been expressly recognized by the father through the record of birth appearing in the civil register, or when an admission in a public document or private handwritten instrument is made by the father.

“Provided, the father has the right to institute an action before the regular courts to prove non-filiation during his lifetime. The legitime of each illegitimate child shall consist of one-half of the legitime of a legitimate child. In granting the respondent’s prayer to change AAA’s name from “AAA [with father’s surname]” as appearing on his certificate of live birth to “AAA [without father’s surname],” the Court of Appeals merely cited Article 176 of the Family Code, as amended, without any discussion on how the cited provision applied to AAA.

“The Court of Appeals seemed to have ignored the second sentence of Article 176, which permits nonmarital children to use the surname of their father, provided that the father expressly recognized their filiation through the record of birth appearing in the civil register, or through an admission in a public document or private handwritten instrument made by the father. There was no mention that the petitioner did not recognize his filiation with AAA for the Court of Appeals to grant the prayer for a change of name. Respondent herself stated in her appeal before the Court of Appeals that AAA was a nonmarital child, being born before she got married to the petitioner.

“As a nonmarital child at the time he was born, AAA should have used the surname of his mother pursuant to Article 176 of the Family Code, as amended. However, the fact that AAA was able to use the surname of his father means that the petitioner expressly recognized his filiation with AAA. That petitioner recognized his filiation with AAA is strengthened by the fact that petitioner vehemently opposed respondent’s petition for adoption with an application for AAA’s change of name. Respondent also never alleged that petitioner did not recognize his filiation with AAA.

“The records reveal that AAA was aware that the petitioner was his father. Petitioner also provided financial support for AAA and was allowed to visit and spend time with his child. Considering that Article 176 of the Family Code allows nonmarital children to use the surname of their father, provided that the father made an express recognition of their filiation, then there would have been no reason for the Court of Appeals to have granted the respondent’s prayer for her minor child’s change of name.

“Respondent’s contention regarding the absence of an affidavit to use the surname of the father as required by the Revised Implementing Rules and Regulations of Republic Act 9255 is misplaced. The Rules apply to nonmarital children whose births were unregistered or previously registered under the surname of the mother. Here, the child’s birth certificate is already registered under the surname of the father, and it is the mother who now wants to change the surname of her child after her marriage with the father was nullified.”

The quoted decision is from G.R. 273935 (18 August 2025). Names of the parties are redacted.