A father writing and signing a document while his young daughter watches closely, representing a father formally recognizing paternity — the step required before an illegitimate child can use his surname under RA 9255 in the Philippines.

How to Change an Illegitimate Child’s Surname to the Father’s Under RA 9255

An illegitimate child in the Philippines is, by default, registered under the mother’s surname. Republic Act No. 9255 changed that default in one specific way: once the father has recognized the child, the child may use the father’s surname instead — but only after that recognition is properly documented and a specific civil-registry document, the Affidavit to Use the Surname of the Father (AUSF), is executed and registered. Many parents assume that naming the father on the birth certificate, or getting him to sign an acknowledgment, is enough by itself. It usually is not. This guide walks through what counts as recognition, what the AUSF process actually requires, where to file it, and what happens if the father is unwilling, unavailable, or has already died.

Direct Answer

Under Article 176 of the Family Code, as amended by RA 9255, an illegitimate child’s surname is the mother’s surname by default. The child may instead use the father’s surname, but only once the father has recognized the child in one of the ways the law treats as valid recognition: being named as the father in the record of birth itself, a public document such as an affidavit admitting or acknowledging paternity, or a private handwritten instrument signed by the father recognizing the child. Recognition by itself does not change what appears on civil-registry records — the surname change happens through a separate document, the AUSF, executed and then registered with the civil registrar that holds the child’s birth record. The Supreme Court has also made clear that using the father’s surname is the child’s option, not something the father or the mother can impose or withhold on the child’s behalf as they see fit. There is no administrative shortcut if the father has never recognized the child and disputes paternity — that situation calls for a judicial filiation case, not an AUSF filing.

Decision Snapshot

  • Applies to: An illegitimate child currently registered under the mother’s surname whose father has recognized, or is willing to recognize, paternity through a legally recognized channel.
  • Default rule without recognition: The child is registered and remains registered under the mother’s surname.
  • What actually changes the surname: Valid recognition of paternity, plus execution and registration of an Affidavit to Use the Surname of the Father (AUSF) at the proper civil registry office.
  • Who decides: The child — the Supreme Court has held that using the father’s surname is discretionary, not something a parent can dictate.
  • If paternity is disputed: The AUSF process is not a substitute for a judicial filiation case; a father who has never recognized the child, or who denies paternity, is a different legal problem with a different remedy.

Key Takeaways

  • RA 9255 amended Article 176 of the Family Code. The mother’s surname remains the default for an illegitimate child; the father’s surname becomes available only after recognition.
  • Recognition can happen through the record of birth itself, a public document (such as an affidavit of admission or acknowledgment of paternity), or a private handwritten instrument signed by the father.
  • Even after recognition exists, the surname does not change automatically — a separate Affidavit to Use the Surname of the Father (AUSF) must be executed and registered with the civil registrar.
  • In Grande v. Antonio (G.R. No. 206248, February 18, 2014), the Supreme Court held that use of the father’s surname is discretionary: the law uses “may,” not “shall,” and neither parent may dictate the child’s surname.
  • Who signs the AUSF depends on the child’s age and circumstances — the Philippine Statistics Authority’s published guidance describes different filers for young children, older minors, and children who have reached the age of majority.
  • A private handwritten instrument, unlike a public document or an entry on the birth record, typically needs to be corroborated by other documents showing the father-child relationship before a civil registrar will accept it.
  • Civil-registry documents not made part of the original birth record — including the AUSF — are generally expected to be registered within a set period of their execution, after which delayed-registration rules apply.
  • This process changes only the surname shown on civil-registry records. It does not, by itself, establish legitimacy, change inheritance shares, or resolve custody, support, or parental-authority questions — those are separate legal issues.

In This Guide

Authority What it governs Relevance here
Family Code of the Philippines (Executive Order No. 209), Art. 176, as amended by RA 9255 Default surname rule for illegitimate children and the conditions under which the father’s surname may instead be used The core rule this entire process is built on
Republic Act No. 9255 (2004) Amends Article 176; establishes the legal basis for an illegitimate child to use the father’s surname upon recognition The statute itself, including the father’s right to impugn the recognition in court during his lifetime
PSA Administrative Order No. 1, Series of 2016 (Revised Implementing Rules and Regulations of RA 9255), as amended by PSA OCRG Administrative Order No. 1, Series of 2023 Defines recognition documents, the AUSF, who executes it by age, supporting-document requirements, the 20-day registration period, and (since 2023) retroactive coverage for births during the Family Code’s effectivity Sets out the actual paperwork and filing mechanics described in this guide; replaced the original OCRG Administrative Order No. 1, Series of 2004
Grande v. Antonio, G.R. No. 206248 (February 18, 2014) Whether use of the father’s surname under Art. 176 as amended is mandatory or discretionary Confirms the child’s right to decide, and declared Rules 7 and 8 of OCRG Administrative Order No. 1, Series of 2004 void insofar as they made the father’s surname mandatory once recognized

Who This Applies To

This process applies to a child who is illegitimate — born to parents who were not married to each other at the time of birth and who has not since been legitimated — and who is currently registered under the mother’s surname, where the father has recognized, or is willing to recognize, paternity. If you or your adult child were born before RA 9255 took effect in 2004 and were previously told this process did not apply because of that birth date, see FamilyCode.ph’s guide on whether RA 9255 applies retroactively to children born before 2004 — a 2023 rule change may have resolved exactly that problem. It does not apply the same way to a child who has already been legitimated through the parents’ subsequent valid marriage; legitimation is a different legal status with its own requirements, covered in FamilyCode.ph’s guide on legitimation of a child born out of wedlock. It also does not apply where paternity is disputed or has never been acknowledged in any of the recognized ways — if the alleged father denies paternity or has simply never taken any of the steps the law treats as recognition, there is nothing yet for an AUSF to build on, and the applicable remedy is a judicial action to establish filiation, discussed in FamilyCode.ph’s guide on establishing paternity and filiation through DNA testing and a court petition.

What Counts as Recognition, and What It Takes to Prove It

Before an AUSF can accomplish anything, the father’s paternity has to be recognized in one of the ways the law accepts. Article 176, as amended, and the related Family Code provisions on proof of filiation recognize three main channels:

1. The record of birth itself

If the father personally signed the child’s Certificate of Live Birth as the informant, or is otherwise named and signed as the father on the record at the time of registration, that entry itself generally functions as recognition — no separate document is needed to establish paternity, though the AUSF is still the document that changes the surname shown.

2. A public document

Most commonly, this is an Affidavit of Admission of Paternity — often available as a standard form attached to or filed alongside the Certificate of Live Birth — in which the father formally acknowledges the child as his own. Because it is a public document, a civil registrar can generally accept it on its face.

3. A private handwritten instrument (PHI)

If the father has, in his own handwriting, written and signed something that recognizes the child as his (a letter, a note, a similar document), that can also serve as recognition. Because a PHI is not a public document, the PSA’s current guidance accepts it only when there are supporting documents to prove filiation. The original 2004 implementing rules (Rule 7.1.2) required any two of the following: employment records, SSS or GSIS records, insurance, a certification of membership in an organization, a Statement of Assets and Liabilities, or an income tax return. Ask the Local Civil Registry Office in advance which supporting documents it currently accepts under the revised rules.

Whichever channel applies, keep in mind that the father retains the right, under RA 9255 itself, to challenge or impugn that recognition through the courts during his lifetime — recognition is not automatically beyond dispute simply because a document exists.

The AUSF Itself: Who Signs, and What Else Is Needed

Once recognition exists, the surname itself changes through the Affidavit to Use the Surname of the Father (AUSF) — a document executed specifically for this purpose and then registered with the civil registrar. The father, the mother, the child (if of age), or the guardian may file the documents. Who executes the AUSF depends on the child’s age under the PSA’s Revised Implementing Rules (PSA Administrative Order No. 1, Series of 2016):

Child’s age Who executes the AUSF
0 to 6 years The mother or the guardian
7 to 17 years The child, with the attestation of the mother or guardian that the child is aware of the consequences
18 and above The child personally, with no attestation needed

Note that for a young child the rules name the mother or guardian, not the father, as the person who executes the AUSF, which fits Grande v. Antonio‘s holding that the choice belongs to the child and not to the father. Confirm the exact forms with the LCRO before preparing documents.

Process: What Generally Happens

  1. Confirm what the birth record already shows. Request a current PSA copy of the child’s birth certificate to see whether the father is already named and signed as informant, or whether no recognition has been documented at all.
  2. Secure a recognition document, if one does not already exist. This means either a public document (an admission or acknowledgment of paternity) or a private handwritten instrument with the required corroborating documents.
  3. Prepare the AUSF. The appropriate person, based on the child’s age and the rules above, executes the affidavit.
  4. Register the documents with the Local Civil Registry Office (LCRO) that holds the child’s birth record — or, for a birth recorded abroad, the office that processed the Report of Birth. Any recognition document or AUSF not already part of the birth record is generally expected to be registered within a set period from execution (the implementing rules specify twenty days), after which delayed-registration procedures apply instead.
  5. LCRO review and annotation. Once accepted, the change is reflected as an annotation on the child’s birth certificate rather than by silently rewriting the original entry, so the record continues to show both the original registration and the later change.
  6. Request updated PSA-certified copies once the annotation has been processed, and ask the LCRO whether a separate Supplemental Report is also needed to enter or update the child’s middle name to reflect the new surname arrangement.

Processing steps, exact forms, and any local fees are set and administered at the LCRO level and can vary somewhat by city or municipality; confirm current requirements directly with the office where you will file rather than relying on a fixed nationwide figure.

Legal Effects, Rights and Limits

The clearest legal effect of Grande v. Antonio is that using the father’s surname is the child’s choice. The Supreme Court was explicit that Article 176, as amended, “gives illegitimate children the right to decide if they want to use the surname of their father or not,” and that neither the father nor the mother is “granted by law the right to dictate the surname of their illegitimate children.” The Court struck down administrative language that had treated the father’s surname as mandatory once paternity was recognized, precisely because it went beyond what the statute’s permissive wording (“may”) actually authorized. In practice, while the child is a minor, this choice is exercised on the child’s behalf by whoever is authorized to execute the AUSF — but the underlying entitlement belongs to the child, not to either parent.

It is also worth being precise about what this process does not do. Completing the AUSF changes the surname shown on civil-registry records; it does not by itself make the child legitimate (that requires legitimation through the parents’ subsequent valid marriage, or does not happen at all if they never marry), and it does not by itself change the child’s inheritance share, which already flows from the fact of acknowledged filiation rather than from the surname on record — see FamilyCode.ph’s guide on the rights of legitimate vs. illegitimate children for how inheritance, support, and surname are related but distinct questions. It also does not resolve or affect parental authority, custody, or support arrangements, which are governed by separate rules.

What to Do Next: Options by Situation

Situation What to do Where
Father signed the birth record or is willing to sign an Affidavit of Admission of Paternity Execute the AUSF (per the age table above) and register it with any recognition document within 20 days of execution LCRO where the birth is registered; Philippine Foreign Service Post for a birth abroad
Only a handwritten letter or note from the father exists Use it as a private handwritten instrument, with supporting documents proving filiation LCRO where the birth is registered
Father has died but recognized the child while alive Proceed with the AUSF using the existing recognition document LCRO
Father denies paternity or never recognized the child Judicial action to establish filiation (DNA testing may be ordered). If there is no signed birth record or written admission, it must be filed while the alleged father is alive (Family Code Art. 175) Family Court; PAO if you qualify
Child was born before 2004 The 2023 amendment extended the rules to all non-marital children born during the Family Code’s effectivity; see the retroactivity guide LCRO
LCRO refuses to register a compliant AUSF Ask for the refusal and its reason in writing, then raise it with the PSA’s Office of the Civil Registrar General, which issues the RA 9255 rules; consult PAO or a lawyer if it is still refused PSA (Office of the Civil Registrar General)

Bring: the child’s PSA birth certificate, the recognition document (or the birth record signed by the father), any supporting documents if relying on a handwritten instrument, and valid IDs of the person executing the AUSF (and of the attesting mother or guardian for a child aged 7 to 17).

Deadline: register the AUSF within 20 days of execution; after that, delayed-registration rules apply. No other fixed deadline for the surname election itself was found in the rules reviewed.

First action: order the child’s PSA birth certificate and call the LCRO where the birth is registered to ask for its AUSF checklist and fees.

If the father is using the surname issue to threaten or control you or the child, or is withholding support, that may be violence under Republic Act No. 9262; see VAWC protection orders.

Common Misunderstandings

  • “If the father is named on the birth certificate, the surname changes automatically.” Being named as father on the birth record can count as recognition, but the surname itself only changes once an AUSF is executed and registered.
  • “The father can require the child to use his surname.” No. The Supreme Court in Grande v. Antonio held this is the child’s decision, not the father’s or the mother’s.
  • “Using the father’s surname makes the child legitimate.” These are separate legal concepts. Legitimacy comes from the parents’ marital status (or subsequent legitimation), not from which surname is used.
  • “This process changes how much the child can inherit.” Inheritance rights for an acknowledged illegitimate child exist because of the acknowledged filiation itself, not because of which surname appears on the birth certificate.
  • “A handwritten note from the father is automatically enough on its own.” A private handwritten instrument is a valid form of recognition, but civil registrars generally require it to be corroborated by other supporting documents before accepting it.
  • “This process works even if the mother is married to someone else.” It does not. This entire RA 9255 process applies only to a child who is legally illegitimate. If the mother is married to a man other than the biological father, the child is instead presumed that husband’s legitimate child by default, and an acknowledgment under RA 9255 cannot override that presumption — see FamilyCode.ph’s guide on what surname a child can use if the mother is still legally married to someone else.

Practical Checklist

  1. Request a current PSA copy of the child’s birth certificate to see exactly what is already on record.
  2. Identify which of the three recognition channels applies — record of birth, public document, or private handwritten instrument — or which one you still need to obtain.
  3. If relying on a private handwritten instrument, gather at least two corroborating documents showing the father-child relationship.
  4. Confirm with the Local Civil Registry Office who is authorized to execute the AUSF for your child’s specific age and situation.
  5. Prepare and execute the AUSF, then register it — along with any recognition document not already part of the birth record — promptly, since delayed registration involves additional procedure.
  6. Follow up on the resulting annotation and request updated PSA-certified copies once it is processed.
  7. Ask the LCRO whether a Supplemental Report for a middle name is also required in your case.
  8. If the father disputes paternity or has never recognized the child through any of the recognized channels, consult a lawyer or the Public Attorney’s Office about a judicial filiation case instead of attempting an AUSF filing.

Frequently Asked Questions

If the father signs the birth certificate as the father, does the child automatically get his surname?

Signing the birth record as the father can count as recognition, but it does not, by itself, change the surname on file. A separate Affidavit to Use the Surname of the Father (AUSF) still needs to be executed and registered for the surname itself to change.

Can the mother stop the child from using the father’s surname, or force it?

The Supreme Court has framed this as the child’s own right to decide, not a choice that belongs to either parent. While the child is a minor, that choice is exercised on the child’s behalf by whoever is legally authorized to execute the AUSF, but neither parent can unilaterally dictate the outcome against what the law and the applicable procedure allow.

What if the father has already died?

If recognition already existed before his death — for example, he was named and signed on the birth record, or executed a public document or private handwritten instrument while he was alive — the AUSF process can generally still proceed based on that existing proof. If he died without ever recognizing the child through any of the recognized channels, the administrative RA 9255 route is not available, and establishing filiation would require a judicial proceeding instead.

How much does this cost, and how long does it take?

Neither RA 9255 nor its implementing rules fix a nationwide peso fee or processing time for registering an AUSF or a recognition document; civil registry fees and turnaround are set and administered at the local civil registry level. Confirm current fees and expected processing time directly with the LCRO where you will file.

What if the alleged father refuses to acknowledge the child at all?

The AUSF process depends on recognition already existing. If the alleged father denies paternity or refuses to cooperate, the available remedy is a judicial action to establish filiation — which can include DNA testing as evidence — rather than an administrative AUSF filing. See FamilyCode.ph’s guide on establishing paternity and filiation through DNA testing.

Related Guides

Sources and Legal Citations

Statutes and codes

  • Family Code of the Philippines, Executive Order No. 209 (1987), Art. 176, as amended — full text via LawPhil
  • Republic Act No. 9255 (2004), An Act Allowing Illegitimate Children to Use the Surname of Their Father — full text via LawPhil

Supreme Court rules and jurisprudence

Official agency material

  • PSA Administrative Order No. 1, Series of 2016, Revised Implementing Rules and Regulations of RA 9255 — Supreme Court E-Library
  • PSA OCRG Administrative Order No. 1, Series of 2023, amending the IRR of RA 9255 (retroactive coverage) — Supreme Court E-Library
  • OCRG Administrative Order No. 1, Series of 2004, original IRR of RA 9255 (Rule 7.1.2 on supporting documents for a private handwritten instrument) — full text via LawPhil
  • Philippine Statistics Authority, official information on Republic Act No. 9255 — psa.gov.ph

Sources rechecked as of: September 28, 2026

This article is general legal information for the Philippines and is not legal advice. Procedures, required documents, and local civil registry practice can vary and change; confirm current requirements with the Local Civil Registry Office where you will file, or consult a Philippine lawyer or the Public Attorney’s Office about your specific situation.

Similar Posts