Below is a comprehensive discussion of the legal framework, requirements, and processes involved in changing a child’s surname to the biological father’s surname under Philippine law. While this article provides an overview of important points, please be aware that it does not constitute formal legal advice. For specific concerns, consult a qualified attorney or approach the appropriate government agencies.

1. Overview and Legal Context

In the Philippines, the rules concerning surnames are primarily governed by:

The Civil Code of the Philippines
The Family Code of the Philippines (Executive Order No. 209, as amended)
Republic Act No. 9255 (the “Revilla Law”), which amended Article 176 of the Family Code
Administrative issuances by the Office of the Civil Registrar General (Philippine Statistics Authority, formerly NSO)

The child’s status—whether legitimate or illegitimate—has a major bearing on whether and how a child can use the father’s surname. The statutes and guidelines lay down specific scenarios under which the child’s surname can be changed or recorded.

2. Differentiating Legitimate and Illegitimate Children

Legitimate Child
A child is considered legitimate if born within a valid marriage (or within 300 days after its dissolution, provided the mother remains unmarried). Legitimate children automatically bear the father’s surname, per the Family Code.
Illegitimate Child
A child is considered illegitimate if born out of wedlock (the parents are not married, or if the child’s parents do not have a valid marriage recognized under Philippine law). By default, an illegitimate child carries the mother’s surname.

The procedure for changing a child’s surname to that of the father’s, in most instances, is relevant primarily when the child is illegitimate. However, there can be rare situations involving correction of clerical errors for legitimate children too. Focus here is on the more typical situation where the child is illegitimate and the parents wish to change the surname to that of the father.

3. Republic Act No. 9255 (The “Revilla Law”)

Passed in 2004, R.A. 9255 amended Article 176 of the Family Code to allow illegitimate children to use the father’s surname, provided that the father acknowledges the child in accordance with law. This recognition can be done through various means, such as:

Executing an Affidavit of Acknowledgment or Admission of Paternity
Signing the child’s birth certificate at the time of birth registration (if paternity is clearly indicated and acknowledged)
A private handwritten instrument where the father expressly recognizes the child as his own

Key Provisions Under R.A. 9255:

Acknowledgment of Paternity is Required
The child can only use the father’s surname if the father recognizes his paternity in the manner required by law.
Consent of the Child (If of Age)
If the child is over 18 years old, generally the child must give consent to any surname change.
Irrevocability of the Choice of Surname
Once the surname is changed to that of the father, courts and administrative offices interpret this as not easily reversed—unless there is a very strong legal ground to do so (e.g., proof that the acknowledgment was erroneous or obtained by fraud).

4. Situations Where Changing the Surname is Relevant

Illegitimate Child Wanting to Use the Biological Father’s Surname
- At birth registration (if not done yet): The father may directly sign the Certificate of Live Birth acknowledging paternity, leading to the child’s use of his surname.
- After birth registration: If the child’s birth certificate is already on file with the mother’s surname, the parents can initiate an administrative proceeding to reflect the father’s surname, contingent on a proper acknowledgment of paternity.
Subsequent Marriage of the Biological Parents
- Under certain conditions, if the biological parents eventually marry, the child may be legitimated by subsequent marriage (Family Code, Art. 177). Once legitimated, the child is considered legitimate from birth and uses the father’s surname. A separate proceeding with the Local Civil Registrar is needed to annotate the birth records.
Court Proceedings
- If the father refuses to acknowledge paternity or if there is a dispute, the mother (or the child) may file a paternity suit in court to establish biological fatherhood. Once confirmed, the father’s name can be used. This is generally more time-consuming and expensive since it requires judicial proceedings.

5. Administrative Process of Changing the Child’s Surname

When a child’s birth certificate is already on file (bearing the mother’s surname) and the father later agrees to acknowledge paternity, the following administrative procedure typically applies:

Execute a Public Document Acknowledging Paternity
- Commonly, this is in the form of an Affidavit of Acknowledgment/Admission of Paternity (AAP). This affidavit should be notarized or executed before a public officer with authority to administer oaths, or in rare cases, acknowledged before a consul if overseas.
Affidavit to Use the Surname of the Father (AUSF)
- Apart from the father’s Affidavit of Acknowledgment, the mother (and/or child if of legal age) must execute an Affidavit to Use the Surname of the Father (AUSF).
- This is required under Administrative Order No. 1, Series of 2004 (and subsequent amendments) issued by the Office of the Civil Registrar General.
Submission to the Local Civil Registrar
- The duly notarized AAP (father’s affidavit) + AUSF (mother/child affidavit) + supporting documents (valid IDs, child’s birth certificate, etc.) must be submitted to the Local Civil Registrar (LCR) where the child’s birth was registered or where the birth certificate is kept.
- Payment of filing fees and processing fees is required.
Issuance of an Annotated Birth Certificate
- Once approved, the LCR will annotate the changes on the birth record, indicating the father’s name and the child’s new surname.
- An annotated copy of the Certificate of Live Birth can then be obtained, reflecting the father’s surname in the child’s legal documents.

Key Points to Note:

If the child is seven (7) years old or above, the LCR may require the child’s consent—though procedures can vary based on local regulations.
If the child is already 18 years old or older, the decision to change the surname legally rests with the child.
If the father’s acknowledgment does not comply with statutory requirements (e.g., unnotarized, improperly executed), the Civil Registrar might deny the request, necessitating correction or judicial action.

6. Court vs. Administrative Proceedings

Administrative Proceeding

When used: If the father voluntarily acknowledges the child, or if the father’s name is in the birth certificate from the start but the child still uses the mother’s surname.
Less complicated: Typically quicker, cheaper, and does not require a formal trial.

Court (Judicial) Proceeding

When used:
- Father denies paternity and a paternity test or court ruling is needed.
- There is a serious question about the authenticity of documents or the father’s identity.
- The mother or the child needs a final judicial declaration to require the father’s recognition.
More complex: Involves litigation costs, time-consuming processes, and possible appeals.

7. Rights and Obligations After the Surname Change

Child’s Rights
- Using the father’s surname may help clarify inheritance rights, although for illegitimate children, inheritance shares remain governed by applicable laws on illegitimate succession.
- The father may become obligated to provide support in accordance with law (the father’s duty to support his child exists once paternity is established, regardless of the child’s surname).
Father’s Obligations
- Acknowledging paternity establishes legal responsibility for child support.
- The father also stands to have custody or visitation rights, depending on the best interests of the child and the child’s age.
Mother’s Rights
- Even if the child uses the father’s surname, the mother retains parental authority unless there are other legal determinations on custody.
- The mother may demand child support from the father based on the recognition of paternity.

8. Legitimation by Subsequent Marriage

If the biological parents of an illegitimate child later contract a valid marriage, the child may be legitimated by that subsequent marriage. Under Article 177 of the Family Code, legitimation has the effect of making the child legitimate from birth.

Requirements:

At the time the child was conceived, the parents were not disqualified from marrying each other under Philippine law.
A Legitimation Paper or a petition with the Local Civil Registrar is filed, along with the parents’ Marriage Certificate and the child’s Birth Certificate.

Once legitimation is approved, the child’s surname is changed to that of the father, and a new (or annotated) birth certificate is issued, reflecting the change.

9. Potential Complications and Considerations

Father’s Refusal to Acknowledge
- If the father does not voluntarily execute any affidavit, a court action for paternity and support is typically necessary.
Multiple Acknowledgments
- In rare, complicated situations where there might be more than one person claiming or disclaiming paternity, the local civil registrar might require a court ruling to clear the issue.
Timing and Emotional Factors
- There may be emotional, family, and personal dynamics that come into play, especially in contested paternity cases.
- The decision to change a surname can also affect a child’s sense of identity.
Finality of Change
- Once changed, reversing or reverting to the mother’s surname usually requires a judicial process (unless the child is a minor and certain procedural requirements are met).
Costs and Wait Times
- Administrative fees and potential attorney fees (if going through court) can vary across regions. Processing times at the LCR can range from a few weeks to several months, depending on the complexity and local backlog.

10. Practical Steps Summary

Secure Recognition of Paternity
- Father should sign an Affidavit of Acknowledgment or Admission of Paternity (AAP).
- Have it notarized or executed before a proper official.
Affidavit to Use the Surname of the Father (AUSF)
- The mother (or the child, if of age) prepares and signs the AUSF.
- Attach all required identification documents.
Submit to the Local Civil Registrar
- Bring the original birth certificate and the executed affidavits (AAP and AUSF).
- Pay the processing fees.
Wait for Approval and Annotation
- The Local Civil Registrar will annotate the birth certificate to indicate the new surname.
- Obtain a certified copy of the annotated birth certificate.
Update All Records
- After obtaining the annotated birth certificate, update the child’s school records, government IDs, passports, bank accounts, and other official documents.

11. Conclusion

Changing a child’s surname to the biological father’s surname in the Philippines is a process largely guided by R.A. 9255, relevant provisions of the Family Code, and specific administrative guidelines. The father’s recognition or acknowledgment of paternity is the cornerstone of this process for illegitimate children. Once acknowledged, a combination of affidavits and administrative steps is usually sufficient, unless a legal conflict arises—then judicial intervention may be required.

For parents considering this change, it is important to plan carefully, ensuring you meet all requirements. Should doubts or conflicts over paternity or documentation arise, it is advisable to seek the assistance of a lawyer. Familiarizing yourself with the procedures—and working closely with the local civil registrar—will greatly streamline the process and ensure that the child’s legal identity accurately reflects the father’s recognition.