Under Philippine law, the naming conventions for illegitimate children have undergone significant shifts, primarily driven by the evolution of the Family Code and Republic Act No. 9255. For many mothers or children seeking to revert to the mother’s surname, the process involves navigating specific administrative and judicial hurdles.

1. The Default Rule: Article 176 of the Family Code

Originally, Article 176 of the Family Code mandated that illegitimate children shall use the surname of their mother. This was designed to establish a clear legal link between the child and the parent whose filiation is undisputed at birth.

However, the law was amended by Republic Act No. 9255 (2004), which allowed illegitimate children to use the father’s surname if:

The father expressly recognizes the child through the Record of Birth; or
The father executes an Affidavit of Admission of Paternity or a Private Handwritten Instrument.

2. Can the Surname Be Changed Back?

The short answer is yes, but the "how" depends on how the father’s surname was acquired in the first place and the child's age.

A. Administrative Correction (R.A. 9048 as amended by R.A. 10172)

If the father's surname was registered due to a clerical error or under specific administrative circumstances where paternity was not actually proven or documented correctly, an administrative correction through the Local Civil Registrar (LCR) might be possible. However, this is rarely applicable for a full change of surname based on a change of heart or parental relationship.

B. Judicial Petition for Change of Name (Rule 103)

This is the standard route for most individuals. A petition is filed in the Regional Trial Court (RTC) where the petitioner resides. To succeed in dropping the father’s surname in favor of the mother’s, the petitioner must provide "concurring and compelling" reasons.

Valid Grounds often recognized by Philippine Courts:

When the surname is ridiculous, tainted with dishonor, or extremely difficult to write or pronounce.
When the change is necessary to avoid confusion.
When the child has been continuously using the mother’s surname and is known by it in the community.
When the father has abandoned the child or failed to provide support, and the child wishes to sever the symbolic legal tie.

3. Significant Jurisprudence: The Grande v. Antonio Doctrine

In the landmark case of Grande v. Antonio (G.R. No. 206248), the Supreme Court clarified that the use of the father's surname by an illegitimate child is permissive, not mandatory.

Even if a father recognizes the child, the mother (as the sole holder of parental authority) or the child (upon reaching majority) can decide whether or not to use the father's name. The court emphasized that the child’s best interest is the paramount consideration. If the use of the father's surname causes more harm than good, or if the mother chooses not to use the "option" granted by R.A. 9255, the child reverts to the mother's surname.

4. The Process of Reversion

If an illegitimate child currently uses the father’s surname and wishes to remove it, the following steps are generally involved:

Preparation of Petition: A formal petition for Change of Name under Rule 103 of the Rules of Court.
Publication: The law requires the petition to be published in a newspaper of general circulation once a week for three consecutive weeks. This is to notify the public and the State (through the Office of the Solicitor General).
Hearing: The petitioner must prove in court the grounds for the change. If the child is a minor, the mother, as the legal guardian, files on the child's behalf.
Judgment and Registration: Once the court grants the petition, the decree is registered with the LCR where the birth was recorded and the Philippine Statistics Authority (PSA).

5. Summary of Key Constraints

Parental Authority: Since the mother has sole parental authority over an illegitimate child (Article 176), she has a strong legal standing to determine the child’s surname during the child's minority.
Consent: If the child is of age (18 or older), the decision rests solely with the child.
Identity Consistency: Courts are often hesitant to change surnames if it appears the petitioner is trying to evade civil or criminal liabilities.

6. Comparison Table: Mother’s vs. Father’s Surname

Aspect	Use of Mother's Surname	Use of Father's Surname (R.A. 9255)
Legal Basis	Mandatory default (Art. 176)	Optional/Permissive
Requirement	Fact of birth to an unmarried woman	Express recognition/Affidavit of Paternity
Parental Authority	Solely with the Mother	Remains solely with the Mother
Reversion	N/A	Possible via Court Order (Rule 103)