Introduction

Changing a child’s surname to that of the father after the latter has voluntarily acknowledged paternity is a fairly common request in the Philippines. The governing rules sit at the intersection of civil‑status law (the Family Code), civil‑registration statutes (Republic Acts 9048, 9255, 10172 & 9858), and procedural rules of court (Rules 103 & 108 of the Rules of Court). Because “surname” (or “last name”) is considered a substantial element of civil status, the Philippines distinguishes between:

Administrative correction handled by the Local Civil Registry (LCR) or the Office of the Civil Registrar General (OCRG) when the law expressly allows it; and
Judicial proceedings in the proper Regional Trial Court (RTC) when a statute requires a court order.

Below is a practitioner‑style guide that gathers everything you need to know. It assumes the child was already registered under the mother’s surname and the father subsequently executed, or is ready to execute, an acknowledgment of paternity.

1. Statutory & Regulatory Bases

Primary Source	Key Point
Art. 176, Family Code (as amended by RA 9255)	An illegitimate child ‑ now “non‑marital child” ‑ may use the father’s surname if (a) the father acknowledges the child and (b) the AUSF procedure is followed.
RA 9255 (2004) & Administrative Order (A.O.) No. 1‑2004	Creates the Affidavit to Use the Surname of the Father (AUSF) route and details documentary requirements & LCR workflow.
RA 9048 (2001), RA 10172 (2012)	Allow administrative changes for clerical errors, first name, day/month of birth, or sex but not surnames (exceptions: RA 9255 & legitimation).
Art. 177‑182, Family Code	Legitimation by subsequent marriage: child automatically becomes legitimate; surname changes to father’s without a court petition (handled via LCR annotation).
RA 9858 (2009)	Legitimation of children born to parents who were below 18 at the child’s birth; surname changes to father’s administratively.
Rule 103, Rules of Court	Judicial petition to change name (e.g., switching “de la Cruz” to “Garcia”).
Rule 108, Rules of Court	Judicial corrections/changes to civil‑registry entries when the matter is substantial (e.g., parentage, legitimacy) and not covered administratively.

2. Routes for Changing the Child’s Surname

2.1 Administrative: Affidavit to Use the Surname of the Father (AUSF)

This is the preferred and fastest path when the child is illegitimate but acknowledged:

Who may file?
- If the child is below 7 years – the mother.
- If 7–17 years – the child signs the AUSF with the mother’s consent.
- If 18 years or older – the child alone.
Where to file?
- Local Civil Registry of the city/municipality where the birth was recorded, or where the child resides.
Core documents
- Original PSA (formerly NSO)‑certified birth certificate.
- Public instrument of acknowledgment (e.g., father signed at the back of the birth certificate, executed a notarized Affidavit of Acknowledgment/Admission of Paternity, or acknowledged in a will).
- AUSF (standard form under A.O. 1‑2004).
- Valid IDs of filing party/parties.
- fees (₱3,000 OCRG fee + LCR fee; varies locally).
LCR process
- LCR examines completeness; forwards to PSA Civil Registrar General for approval.
- Once approved, the LCR annotates the birth certificate:
  
  “The child is hereby allowed to use the surname of his/her father pursuant to RA 9255….”
- PSA issues a newly‑annotated certificate of live birth (approx. 2–3 months).
Effect: Child remains illegitimate (unless later legitimated or adopted) but legally bears the father’s surname for all purposes (passport, school records, PhilHealth, etc.).

2.2 Administrative: Legitimation

a. By Subsequent Marriage (Art. 177, Family Code)

If the parents marry each other after the child’s birth and no legal impediment existed between them at the time of conception:

File a Petition for Legitimation by Subsequent Marriage with the LCR where the child was registered.
Attach: authenticated marriage certificate, child’s PSA birth certificate, ID of parents, affidavit of legitimation.
LCR forwards to PSA. Once approved, the civil‑registry entry is annotated; the child becomes legitimate and automatically uses the father’s surname.

b. Special Legitimation Under RA 9858

Where parents were below 18 (but otherwise capable of marrying) when the child was conceived/born and later cohabit or marry: same steps as above; no court appearance.

2.3 Judicial: Rule 103 Petition to Change Surname

Required when:

The child is legitimate but wants to adopt the surname of the father who acknowledged paternity only after the birth record was completed with the mother’s surname (unlikely but possible in complex cases).
There is opposition or doubt as to voluntariness/validity of acknowledgment.
A clerical‑error path is unavailable because the entry to be changed is substantial (surname).

Procedure (summary):

Verified Petition filed in the RTC of the province where petitioner resides (or where the civil registry is).
Parties: Petitioner versus the Republic of the Philippines (through the Office of the Solicitor General & the Local Civil Registrar).
Publication: Order is published once a week for three successive weeks in a newspaper of general circulation.
Hearing: RTC receives evidence of (a) paternity acknowledgment, (b) absence of intent to defraud, (c) good cause (e.g., best interest of the child).
Decision: If granted, the order is registered with the LCR & PSA; annotations follow.

Estimated timeline: 4–12 months; costs are higher due to filing fees (₱4‑6 k), publication (₱10‑15 k or more).

2.4 Judicial: Rule 108 Correction/ Cancellation of Entry

Invoked where multiple civil‑status matters converge (e.g., a simultaneous petition for acknowledgment of paternity and surname change). The petition may pray for:

Entry of the father’s name in the “Father” field, and
Substitution of the child’s surname with the father’s.

Because paternity goes beyond a mere clerical error, only a Rule 108 adversarial proceeding can do both in one go. The steps mirror Rule 103 (notice, publication, hearing) but the petition is captioned “In the matter of correction of entry in the civil registry…”.

3. Practical Checklist of Documentary Requirements

Scenario	Key Documents
AUSF (RA 9255)	PSA birth certificate, Public instrument of acknowledgment (or simulated if executed now), AUSF form, mother’s consent (if child <18), data-preserve-html-node="true" IDs, fees.
Legitimation by subsequent marriage	PSA birth certificate, PSA marriage certificate, joint affidavit, IDs, fees.
Legitimation under RA 9858	PSA birth certificate, joint affidavit, IDs of parents, proof of subsequent cohabitation/marriage.
Rule 103	Verified petition, newspaper publication proofs, PSA records, acknowledgment docs, birth/marriage certificates, judicial affidavits of witnesses, OSG & LCR notice.
Rule 108	Same as Rule 103 plus all civil‑registry instruments (to prove correction sought) and service of summons on all indispensable parties (parent(s), child if of age).

4. Frequently‑Encountered Special Issues

Father refuses or is abroad. Without his acknowledgment document, RA 9255 cannot be used. Options: persuade father to execute an Affidavit of Admission of Paternity (may be consularized abroad) or file a Rule 108 petition to prove filiation (using DNA, letters, support remittances).
Child already carries the father’s surname socially (school, passport via DFA “courtesy”), but the PSA record is unchanged. Airline/bookings and inheritance will eventually require alignment; follow AUSF or judicial route ASAP.
Birth certificate shows wrong middle name once surname changes. After AUSF, the middle name should remain the mother’s maiden surname; no need to amend unless it is misspelled.
Passport & PhilSys ID update. Present the annotated PSA birth certificate to DFA or PSA‑PhilSys office; no court order is required if AUSF/legitimation route was followed.
Inheritance & legitimation. Using the father’s surname via RA 9255 does not change status from illegitimate; legitimation (or adoption) is required to acquire legitimate status and full succession rights.

5. Timeline & Fees (Typical Metro Manila)

Step	Administrative Route	Judicial Route
Filing to release of annotated PSA copy	2–3 months; ₱3–5 k total	4–12 months; ₱25–40 k (inclusive of publication & lawyer’s fees)
Additional IDs/passport update	2–4 weeks; ₱950 (passport rush)	Same, after court order registration

6. Selected Jurisprudence

Republic v. Court of Appeals & Trinidad, G.R. No. 124535 (1997) – clarified that Rule 108 can cover substantial corrections if proper notice & hearing are observed.
Dionisio v. People, G.R. No. 167109 (2010) – held that paternity acknowledgment does not automatically legitimate a child; separate legitimation process is required.
Labastilla v. CA, G.R. No. 152547 (2004) – recognized the AUSF mechanism under RA 9255 as a valid means to adopt father’s surname.

7. Practical Tips for Petitioners

Name consistency matters. Make sure the names on IDs, acknowledgment instrument, and AUSF exactly match, including middle initials.
Photocopy everything. LCRs often require multiple copies; bring 3 × original PSA birth certificates.
Track your LCR. Small municipalities sometimes forward papers to PSA only monthly; politely follow up.
Retain receipts. Passport, PhilHealth, SSS, DepEd & CHED offices will ask for official receipts of the civil‑registry annotation.
Engage counsel early if the father is absent or relations are strained; contested Rule 108 cases take longer and benefit from early evidentiary planning (e.g., DNA).

Conclusion

The Philippines offers an administrative shortcut (RA 9255 AUSF) for most children who wish to bear their father’s surname after paternity acknowledgment; it is quick, inexpensive, and does not alter legitimacy. Where legitimation is possible, that avenue not only changes the surname but elevates the child’s civil status. Judicial recourse under Rules 103 or 108 remains available when the law requires a court’s imprimatur—particularly for surname changes outside the AUSF and legitimation frameworks or when substantial civil‑status issues are in dispute.

Disclaimer: This article is for general informational purposes and is not a substitute for personalized legal advice. Always verify current LCR fees and forms, and consult a Philippine lawyer for case‑specific guidance.