How to Change a Child’s Surname to the Father’s Name (if Acknowledged) in the Philippines

At a glance: In the Philippines, an illegitimate child may use the father’s surname if the father has expressly acknowledged the child. This can usually be done administratively (no court case) by filing an Affidavit to Use the Surname of the Father (AUSF) with the Local Civil Registry (LCR), together with proof of the father’s acknowledgment. If acknowledgment is absent or contested, the route is judicial (a court case to establish filiation).

1) Legal foundations

Family Code, Art. 176 (as amended by R.A. 9255): Illegitimate children shall use the mother’s surname by default, but may use the father’s surname if the father expressly recognizes the child in the civil register (record of birth) or in a public instrument (e.g., notarized document) or will. Parental authority remains with the mother despite the child using the father’s surname, unless a court orders otherwise.
Administrative route vs. court route:
- Administrative (no court): Possible when there is documentary acknowledgment by the father and the situation fits the implementing rules (AUSF framework).
- Judicial (court): Needed when (a) no acknowledgment exists and the father refuses or is unable to execute one; (b) conflicts exist (e.g., disputes about paternity/consent); or (c) the LCR/PSA cannot act under the limits of the AUSF rules.
Clerical Error Law (R.A. 9048, as amended by R.A. 10172): This law covers clerical/typographical corrections and change of first name—not a change from mother’s to father’s surname. Surname change for illegitimate children hinges on R.A. 9255 and its rules or a court order.
Key jurisprudence (for context): Courts have clarified issues on surnames, recognition, and name changes. While outcomes can vary with facts, one constant is that recognition (filiation) is the gateway to using the father’s surname; the act of using the father’s surname does not itself change the child’s status (still illegitimate) nor automatically give the father parental authority.

2) Who qualifies for the administrative route?

You can generally proceed without filing a court case if:

The child is illegitimate (parents were not married to each other when the child was conceived/born, and the child has not been legitimated or adopted); and
The father has expressly acknowledged the child using any of the following:
- Record of birth (Certificate of Live Birth) signed by the father; or
- An Affidavit of Admission of Paternity (AAP) executed by the father; or
- A public instrument (e.g., notarized acknowledgment) or will clearly acknowledging the child.

Important: If the father’s name appears on the birth certificate but there is no signature or valid acknowledgment, that may not count as express recognition. In practice, the LCR will look for the father’s signature or a separate AAP/public instrument.

3) Two documents you’ll hear about a lot

AAP (Affidavit of Admission of Paternity) – executed by the father to acknowledge the child. This is used when the father’s acknowledgment was not captured at birth registration.
AUSF (Affidavit to Use the Surname of the Father) – the formal request to use the father’s surname.
- If the child is below 18, the mother (as the person with parental authority) usually executes the AUSF on the child’s behalf.
- If the child is 18 or older, the child personally executes the AUSF.
- The AUSF works only if acknowledgment (by AAP, signed birth record, or public instrument) already exists. Otherwise, the LCR cannot grant the use of the father’s surname administratively.

4) Step-by-step: Administrative process at the LCR

Step 1: Gather proof of acknowledgment

Preferred proof:
- Father’s signature on the child’s Certificate of Live Birth; or
- AAP signed by the father; or
- Public instrument / will clearly acknowledging the child (properly notarized; if executed abroad, apostilled or consularized as required).
If the father is abroad, he can execute the AAP/acknowledgment before a Philippine consulate or have it notarized and apostilled under the Apostille Convention.

Step 2: Prepare the AUSF

Minor child (<18): data-preserve-html-node="true" AUSF is typically signed by the mother.
Adult child (≥18): AUSF is signed by the child.
Bring valid IDs, the child’s PSA or LCR copy of the birth certificate, and the acknowledgment proof above.

Step 3: File with the LCR

File at the LCR of the place of birth. Some LCRs will accept filing at the LCR of the place of residence for forwarding. If the birth was reported abroad (Report of Birth), coordinate with the Philippine Foreign Service Post or the LCR per local practice.
Pay applicable fees (varies by LGU).

Step 4: Annotation & transmittal

If the LCR finds the documents sufficient, it will annotate the civil registry record and transmit to the PSA.
You’ll later request a PSA-issued, annotated birth certificate showing the change (often with a marginal note referencing the AUSF).

Tip: Keep both a clear copy of the acknowledgment (AAP/public instrument) and the annotated PSA birth certificate. They’re repeatedly needed for school, passport, bank, and government records updates.

5) Special scenarios & practical notes

A) Father is deceased

If the father died but left a public instrument/will acknowledging the child (or a properly signed birth record exists), the AUSF route may still be available.
If no acknowledgment exists and the father has passed away, the usual remedy is a court action to establish paternity (the court may consider evidence like DNA, admissions, and other proof). After a final judgment, the LCR/PSA can annotate the record.

B) Father refuses or cannot execute acknowledgment

Administrative route won’t apply. The mother/child may file a petition in court to establish filiation. After a favorable judgment, proceed to annotate and use the father’s surname.

C) Newborn registration (best time to avoid back-and-forth)

If both parents are present at birth registration and the father acknowledges on the spot (signs the birth record and/or executes AAP), the child’s record can immediately carry the father’s surname, and the AUSF step is integrated into the registration workflow.

D) Middle name rules (frequent source of confusion)

As a general rule, illegitimate children do not carry a middle name.
If an illegitimate child is allowed to use the father’s surname, treatment of the middle name has evolved in practice. Some LCRs/PSA workflows may allow the mother’s maiden surname as a middle name in specific scenarios, while others keep no middle name. Expect variation; follow your LCR’s current written guidance.

E) Parental authority and custody

Using the father’s surname does not change the child’s status (still illegitimate) and does not transfer parental authority to the father. The mother keeps parental authority unless a court orders otherwise (e.g., custody/visitation arrangements based on the child’s best interests).

F) Legitimation by subsequent marriage / Adoption

If the parents later marry, legitimation rules under the Family Code can apply; the child’s status and surname may change following those provisions.
Adoption is another route that changes status and surname, but it is separate from R.A. 9255 and follows a judicial or administrative adoption process.

G) DNA testing

Not required for the administrative route (since acknowledgment is documentary).
May be ordered by the court in judicial proceedings when paternity is disputed.

H) Adding the father’s details to a “fatherless” birth record

If the original birth record omitted father’s details, you usually file both:
1. AAP (to insert the father’s details), and
2. AUSF (to authorize the use of the father’s surname).
LCRs often process these together when the child is illegitimate and the father now wishes to acknowledge.

I) Documents executed abroad

Documents must be properly notarized and apostilled (or consularized) depending on where they were executed so the LCR/PSA can recognize them.

6) What changes across your records?

Once the PSA issues the annotated birth certificate reflecting the father’s surname:

You can update school and employment records, PhilID, passport, GSIS/SSS/PhilHealth, bank, and government records.
Bring the annotated PSA birth certificate (and, if asked, copies of the AUSF/AAP or acknowledgment instrument) to support the updates.

7) When the administrative route is not available

You’ll need to go to court if:

There is no acknowledgment and the father refuses or is unable to execute one;
The father’s alleged acknowledgment is invalid/contested;
There is a conflict (e.g., disagreement between parents, duplicate records, questions about authenticity); or
The LCR/PSA declines to annotate because the case falls outside their administrative authority.

Judicial options typically involve:

A petition to establish filiation/paternity (Family Code); and/or
A petition under the Rules of Court (Rule 103/108) for change/correction of entries. When the court issues a final judgment, the LCR/PSA will implement the ordered annotations.

8) Common pitfalls (and how to avoid them)

Unsigned father’s entry on the birth certificate: Not enough. Secure an AAP or public instrument of acknowledgment.
Using the father’s surname informally (school, IDs) without PSA annotation: Expect problems later (passport, banking, licensure). Always obtain the PSA-annotated record first.
Assuming the father gains parental authority by surname use: He doesn’t. Mother retains parental authority absent a court order.
Thinking R.A. 9048 can change the surname from mother to father: It can’t. That change is under R.A. 9255 (or court).
Deceased father with no acknowledgment: Administrative route won’t work. Consider a court case to prove filiation (evidence/DNA).

9) Practical checklist

Confirm eligibility: Child is illegitimate + father’s acknowledgment exists.
Secure documents:
- Child’s birth certificate (LCR/PSA copy)
- AAP or public instrument/will; or signed birth record
- AUSF (mother if minor; child if adult)
- Valid IDs of signatories; supporting civil IDs/records
- If executed abroad: apostille/consularization
File at LCR: Pay fees, get receiving copy.
Wait for PSA annotation: Then request PSA-issued annotated birth certificate.
Update downstream records: School, passport, PhilID, SSS/GSIS/PhilHealth, banks, etc.

10) FAQs

Q: Does using the father’s surname make the child legitimate? A: No. The child’s status remains illegitimate unless later legitimated (e.g., parents marry and the law allows legitimation) or adopted.

Q: Can the father force the use of his surname? A: No. The law says the child may use the father’s surname upon acknowledgment; for minors, the mother exercises parental authority. Disputes go to court, which decides based on the child’s best interests.

Q: We can’t find the father. Can we still change the surname? A: Not administratively. You’ll need to establish filiation through a court case; the court may consider DNA or other evidence.

Q: What about the child’s middle name? A: As a rule, illegitimate children have no middle name. Some LCR/PSA practices allow the mother’s maiden surname as the middle name when using the father’s surname, but policies vary. Follow your LCR’s current written guidance.

Q: The father acknowledged the child but I prefer the mother’s surname. Can we keep it? A: Yes. Recognition gives the option to use the father’s surname; it is not mandatory.

Final word

Changing an illegitimate child’s surname to the father’s name in the Philippines is straightforward if the father’s acknowledgment is already on record. The AUSF process at the LCR is the usual path. If acknowledgment is missing or contested, consult counsel about a judicial petition to establish filiation and obtain the court orders needed for PSA annotation.