Below is a general overview of the legal framework, key considerations, and procedures relevant to changing a child’s surname in the Philippines for reasons of paternity or acknowledgment. This is not legal advice. For specific concerns, it’s always best to consult a qualified attorney or visit the Philippine Civil Registry for guidance.

1. Legal Framework

1.1. The Family Code of the Philippines

Article 176 of the Family Code (as amended by Republic Act No. 9255) provides the basis for determining the surname of an illegitimate child. Originally, an illegitimate child was required to use the surname of the mother. However, with the enactment of Republic Act (R.A.) No. 9255, an illegitimate child may use the father’s surname if the father duly acknowledges or recognizes the child in accordance with law.

1.2. Republic Act No. 9255 (“Revilla Law”)

Signed into law in 2004, R.A. 9255 introduced the specific mechanism allowing illegitimate children to use the father’s surname under certain conditions.
It is commonly referred to as the “Revilla Law,” though its official name is “An Act Allowing Illegitimate Children to Use the Surname of their Father” and it explicitly amends Article 176 of the Family Code.

1.3. Civil Registry Laws and Implementing Rules

The administrative procedures for acknowledging paternity or changing a child’s surname are guided by:
- Republic Act No. 9048 (and its amendment R.A. 10172), governing certain administrative corrections in the civil registry.
- Administrative Orders issued by the Philippine Statistics Authority (PSA) or the (former) National Statistics Office (NSO).
- Local Civil Registrar (LCR) guidelines.

2. Acknowledgment of Paternity

2.1. Definition

Acknowledgment of paternity is a formal declaration by a man claiming to be the father of the child. This can be done:
- In the birth certificate (at the time of registration),
- Through an affidavit of acknowledgment or affidavit of admission of paternity,
- In a public document or private handwritten instrument signed by the father.

2.2. Significance

Once acknowledged, the child acquires certain rights, including:
- The right to use the father’s surname (subject to procedures under R.A. 9255 and relevant regulations),
- The right to receive support from the father,
- Certain inheritance rights (consistent with the Family Code and the New Civil Code).

2.3. Timing and Method of Acknowledgment

At the time of birth registration
- If both parents go to the Local Civil Registrar right after birth, the father may acknowledge the child on the birth certificate itself.
- In this scenario, the surname of the father appears on the birth certificate if all requirements are met.
After the birth certificate is already registered
- If the father was absent or initially refused or was unknown, the father can later execute an Affidavit of Acknowledgment or Admission of Paternity.
- The affidavit must be registered with the LCR and annotated on the child’s birth certificate.
Court recognition
- In contested situations or where the father does not want to acknowledge but the mother (or child’s guardian) seeks recognition, a judicial process (paternity suit) might be necessary.

3. When and How a Child’s Surname May Be Changed

3.1. Child is Illegitimate, Father Acknowledges Paternity (R.A. 9255)

Original Rule (Prior to R.A. 9255): An illegitimate child should use the mother’s surname.
Under R.A. 9255: An illegitimate child may use the father’s surname if:
1. The father has duly recognized or acknowledged the child.
2. The father and mother (or guardian, if the mother is a minor or incapacitated) consent to using the father’s surname.
3. Documentary requirements are submitted to the Local Civil Registrar.

Procedure (Administrative):

Execute an Affidavit of Acknowledgment or Admission of Paternity if not yet on record.
File a Public Instrument (e.g., affidavit) before a notary public or appropriate office stating the desire to have the child use the father’s surname.
Submit documents to the Local Civil Registrar where the child’s birth was registered:
- Affidavit of Acknowledgment/Admission of Paternity (if not yet reflected on the birth certificate),
- Certified true copy of the child’s birth certificate,
- Other supporting documents the LCR may require (IDs, proof of filiation, etc.).
Annotation on the birth certificate: The LCR will annotate the child’s birth certificate indicating the father’s acknowledgment and the change in surname.

3.2. Legitimated Children

Legitimation occurs if the child’s biological parents subsequently marry after the child’s birth, provided there was no legal impediment to marry each other at the time of conception.
Under Article 177 of the Family Code, once legitimated, the child may carry the father’s surname. The procedure is generally administrative through the LCR.

3.3. Judicial Proceedings to Change Surname

If there are disputes—e.g., the father’s refusal to give consent or uncertainty about the child’s paternity—this might require filing a Petition for Change of Name in court under Rule 103 of the Rules of Court or a petition for “Correction of Entries” under Rule 108.
A judicial determination may be necessary where the civil registrar cannot process the changes administratively due to lack of consent, disputed paternity, or other complexities.

4. Key Requirements and Considerations

4.1. Documentation

Birth Certificate of the child (original and certified true copy).
Valid IDs of the mother, father, and the child’s guardian (if applicable).
Affidavit of Admission of Paternity / Acknowledgment (if not already on the birth record).
Consent of the mother or the guardian (if the child is a minor and mother is unavailable or incapacitated).

4.2. Parental Consent and Unity

If the child is still a minor, the mother’s or legal guardian’s consent is typically required for the father’s surname to be used.
If the parents are married, the child is presumed legitimate and the father’s surname is used by default—no additional procedure is typically required other than normal birth registration.

4.3. Age of the Child

Changing the surname of a minor is more straightforward than for an adult. If the child is already of legal age (18+), they may need to personally consent or file the application/petition themselves.

4.4. Best Interest of the Child

In court proceedings, judges often apply the “best interest of the child” principle. Even if the father is willing, the court might look at whether using the father’s surname is beneficial to the child’s welfare.

5. Steps to Take in Practice

Confirm Paternity
- Make sure there’s a clear acknowledgment of paternity or a basis for recognition (DNA tests are sometimes used if paternity is contested).
Gather Necessary Documents
- Obtain certified true copies of the child’s birth certificate and relevant affidavits.
Determine Applicable Procedure
- Administrative route if there is no dispute and both parents (and the child, if of age) consent.
- Judicial route if contested or more complicated, e.g., the father denies paternity or there are errors that cannot be corrected administratively.
Consult the Local Civil Registrar
- Most LCRs have a standard procedure or checklist for changes/corrections to birth records.
- Ask about any local guidelines or additional documentary requirements.
Execute and Submit Documents
- Submit the Affidavit of Acknowledgment and a written request (often an application form) for the child to use the father’s surname.
- Pay the corresponding fees and wait for the LCR’s confirmation of the annotation or issuance of an updated birth certificate.
If Needed, File a Court Petition
- If the LCR determines that a court order is needed, secure legal counsel and initiate the appropriate petition.

6. Frequently Asked Questions

Can an illegitimate child automatically use the father’s surname once acknowledged?
- Not automatically. The father’s acknowledgement is a precondition, but the legal/administrative steps must still be taken (Affidavit of Acknowledgment + annotation in the civil registry).
What if the father refuses to acknowledge the child?
- The mother or guardian may file a paternity suit in court. Upon a favorable judgment, the court can order changes to the child’s records and enforce support obligations.
Does changing the surname affect the child’s legitimacy status?
- No. Legitimacy or illegitimacy is a separate matter from the surname. Even if an illegitimate child uses the father’s surname, the status remains illegitimate unless legitimated through the subsequent valid marriage of the parents (or via adoption, if applicable).
How long does the process take?
- Administrative changes can be relatively quick (several weeks to a few months), while judicial proceedings can take longer, depending on court schedules and complexities.
What if the child is an adult and wants to start using the father’s surname?
- If paternity was never acknowledged, the father can still execute an affidavit (if he is willing). Otherwise, a court petition might be required.
Are there fees involved?
- Yes. The Local Civil Registrar, notarial services, and possibly publication fees (for court petitions) will require payment.

7. Conclusion

Changing a child’s surname to reflect paternity or acknowledgment in the Philippine context hinges on the principles in the Family Code (particularly Article 176 as amended by R.A. 9255), local civil registry regulations, and potentially court procedures when disputes arise. Key steps include properly acknowledging paternity, completing an administrative or judicial process, and ensuring that the child’s best interests guide any decisions. While the administrative route is generally more straightforward, complicated situations—like contested paternity—necessitate filing a case in court.

Disclaimer: This summary is a broad overview and not a substitute for personalized legal advice. Laws and regulations can change, and local practices may vary. Always consult a qualified professional or your Local Civil Registrar for accurate, up-to-date guidance.