Yes. An illegitimate child in the Philippines may use the father’s surname, but only when the legal requirements are met. The father must have expressly recognized the child, and the proper civil registry documents must be filed, usually including an Affidavit to Use the Surname of the Father, commonly called an AUSF. Just as important: using the father’s surname is a right of the child, not a power of the father to force the child to carry his surname.

For many families, this issue comes up when applying for a PSA birth certificate, school records, a passport, a visa, inheritance documents, or support. The rules can feel confusing because older guides often say one thing, while PSA practice has changed after later Supreme Court and PSA issuances. This article explains the current rule, who may file, what documents are usually needed, where to file, and what problems commonly delay approval.

The Basic Rule: An Illegitimate Child Usually Uses the Mother’s Surname

Under Philippine family law, a child is generally considered illegitimate if the parents were not validly married to each other at the time of the child’s birth and the child has not been legitimated by the parents’ later valid marriage.

The starting rule under Article 176 of the Family Code, as amended by Republic Act No. 9255, is that illegitimate children use the surname of the mother and remain under the parental authority of the mother. The same provision gives an exception: the child may use the father’s surname if the father has expressly recognized the child through the birth record, a public document, or a private handwritten instrument. (Supreme Court E-Library)

In simple terms:

Situation	Usual surname rule
Father has not legally acknowledged the child	Child uses the mother’s surname
Father has acknowledged the child, but no AUSF is filed	Child still uses the mother’s surname
Father has acknowledged the child and a proper AUSF is filed	Child may use the father’s surname
Father wants to force the child to use his surname	Not allowed; the choice belongs to the child

Legal Basis: RA 9255 and Article 176 of the Family Code

Republic Act No. 9255, approved in 2004, amended Article 176 of the Family Code to allow illegitimate children to use the surname of their father.

The law requires express recognition of filiation. “Filiation” means the legal relationship between parent and child. The father’s recognition may appear in:

the record of birth appearing in the civil register;
an admission in a public document, such as an Affidavit of Admission of Paternity; or
a private handwritten instrument made by the father. (Supreme Court E-Library)

A private handwritten instrument must be in the father’s handwriting, signed by him, and must clearly recognize the child as his. PSA Administrative Order No. 1, Series of 2016, defines this document as one made by the father during his lifetime where he expressly recognizes paternity. (Supreme Court E-Library)

The law also says the father may file an action in court to prove non-filiation during his lifetime. In practical terms, this matters when a father later disputes paternity after signing or being recorded as the father.

The Father Cannot Force the Child to Use His Surname

This is one of the most misunderstood points.

In Grande v. Antonio, G.R. No. 206248, February 18, 2014, the Supreme Court ruled that the word “may” in Article 176 is permissive. This means an acknowledged illegitimate child is not required to use the father’s surname. The Supreme Court said the right to choose belongs to the illegitimate child, not to the father or mother. (Supreme Court E-Library)

The Court also rejected administrative rules that made the father’s surname mandatory after recognition. The Supreme Court declared those mandatory portions of the old implementing rules void because administrative rules cannot expand or change the law. (Supreme Court E-Library)

This is especially important in real-life situations such as:

the father wants the child’s surname changed after a custody dispute;
the mother does not want the child’s records disturbed;
the child is already known in school, travel documents, or medical records under the mother’s surname;
an older child or adult does not want to carry the father’s surname despite acknowledgment.

Current PSA Rule: RA 9255 Now Covers More Children Than Before

Older materials often say RA 9255 applies only to children born on or after March 19, 2004. That is no longer the full practical picture.

PSA OCRG Administrative Order No. 1-2023 amended the coverage of the RA 9255 implementing rules. The current amended rule applies to all non-marital children during the effectivity of the Family Code, including unregistered births and registered births where the child uses the mother’s surname. The same issuance states that prevailing RA 9255 rules have retroactive effect for births occurring within and outside the Philippines under that coverage. (Supreme Court E-Library)

The Family Code took effect on August 3, 1988. This means many adults born before RA 9255 but after the Family Code took effect may now have an administrative route through the civil registry, provided the father validly acknowledged them and the required documents are accepted by the LCRO, PSA, or Philippine Foreign Service Post.

For persons born before August 3, 1988, the route may be different and may require closer review by the Local Civil Registrar or PSA because the current RA 9255 implementing coverage is tied to the effectivity of the Family Code.

What Is an AUSF?

An Affidavit to Use the Surname of the Father (AUSF) is the sworn document used to request that an illegitimate child use the father’s surname under RA 9255.

The AUSF is not the same as the father’s acknowledgment.

Think of the process as having two separate parts:

Proof that the father acknowledged the child This may be through the birth certificate, an Affidavit of Admission of Paternity, a public document, or a private handwritten instrument.
A request to use the father’s surname This is the AUSF.

If the father acknowledged the child but no AUSF is filed, the child generally continues to use the mother’s surname. PSA’s revised rules expressly state that an acknowledged illegitimate child uses the mother’s surname if no AUSF is executed. (Supreme Court E-Library)

Who Signs the AUSF?

The signer depends on the child’s age.

Age of child	Who usually executes the AUSF
0 to 6 years old	Mother, or guardian if the mother is absent
7 to 17 years old	The child, with awareness of the consequence, attested by the mother or guardian
18 years old and above	The child, without need of attestation

These age-based rules appear in PSA Administrative Order No. 1, Series of 2016. (Supreme Court E-Library)

In practice, LCROs are careful with minors aged 7 to 17 because the rule requires the child to understand the consequence of using the father’s surname. For adults, the process is more direct because the person can execute the AUSF personally.

Step-by-Step Guide: How to Use the Father’s Surname

Step 1: Check the child’s PSA and local birth records

Start by getting:

a recent PSA Certificate of Live Birth;
a certified true copy from the Local Civil Registry Office (LCRO) where the birth was registered; and
any attachments on file, such as the father’s acknowledgment or earlier affidavits.

This first step avoids wasted trips. Some PSA birth certificates show the father’s name, but the acknowledgment document may not be properly registered. Others show the child under the mother’s surname even though the father signed an acknowledgment at the back of the local birth certificate.

Step 2: Confirm whether the father legally acknowledged the child

The father’s acknowledgment may be shown by:

his signature in the birth record, if properly made;
an Affidavit of Admission of Paternity;
another notarized public document where he admits paternity;
a private handwritten instrument signed by him; or
a court judgment establishing paternity.

If there is no valid acknowledgment, the administrative RA 9255 route will usually not be available. The mother or child may need to consider a court action to establish filiation, especially when support, inheritance, or identity documents are involved.

Step 3: Prepare the AUSF

Use the AUSF form required by the LCRO or Philippine Embassy/Consulate. The affidavit must be sworn before the proper officer, such as:

a notary public in the Philippines;
the local civil registrar when allowed by local practice;
a Philippine consular officer abroad; or
another authorized officer, subject to authentication or apostille requirements when executed abroad.

If the document is signed outside the Philippines, ask the Philippine Embassy or Consulate first. Using a Philippine Foreign Service Post is often cleaner than submitting a foreign-notarized document later, because the PSA rules specifically allow registration through the PFSP for documents executed outside the Philippines. (Supreme Court E-Library)

Step 4: File with the correct office

Where to file depends on where the birth happened and where the documents were executed.

Situation	Where to file
Child born in the Philippines and documents executed in the Philippines	LCRO of the child’s place of birth
Child born abroad and documents executed abroad	Philippine Embassy or Consulate with jurisdiction
Child born abroad but documents executed in the Philippines	LCRO of the place where the document was executed
Birth already registered under mother’s surname	LCRO where the birth was registered, or the relevant PFSP if abroad

PSA also states that when a birth certificate is already registered under the mother’s surname and the father later executes an acknowledgment, the acknowledgment and AUSF should be registered with the civil registry office where the birth was registered. (Philippine Statistics Authority)

Step 5: Register the documents within the required period

The father’s acknowledgment document, private handwritten instrument, or AUSF should be registered within 20 days from execution. If filed beyond that period, delayed registration rules may apply. (Supreme Court E-Library)

Late filing does not automatically mean the request is impossible, but it can add requirements, review time, and possible endorsement to PSA.

Step 6: Wait for annotation and request the updated PSA copy

Once accepted, the LCRO or PFSP records the legal instrument and annotates the birth record. The annotated record is then transmitted or endorsed to PSA so the PSA database can reflect the annotation.

For PSA copy issuance of a birth document affected by RA 9255, the PSA Citizen’s Charter lists documents such as the certified AUSF, certificate of registration of the AUSF, Affidavit of Admission of Paternity or equivalent document, certificate of registration of the AAP, and certified copies of the unannotated and annotated birth certificate.

PSA’s 2024 Citizen’s Charter indicates an estimated processing time of 5 working days for certain premium annotation requests at the CRS East Avenue outlet and 7 working days for regular annotation requests, but this is for the PSA copy issuance/annotation request stage and assumes the documents are complete and accepted.

In real life, the full timeline can be longer because of LCRO processing, document review, transmittal to PSA, courier time, old records, unreadable entries, missing registry numbers, or records that still need manual verification.

Documents Commonly Required

Requirements vary slightly by city, municipality, and Philippine Foreign Service Post, but these are commonly requested:

Document	Purpose
PSA Certificate of Live Birth	Shows the current PSA record
Certified true copy of the local birth certificate	Used to verify the original local registry entry
Affidavit of Admission of Paternity or acknowledgment	Proves the father expressly recognized the child
Private handwritten instrument, if used	Alternative proof of acknowledgment
AUSF	Requests use of the father’s surname
Certificate of registration of the AUSF	Proves the AUSF was registered with the LCRO/PFSP
Certificate of registration of the acknowledgment	Proves the father’s acknowledgment was registered
Valid IDs of the signatories	Confirms identity
Death certificate of the father, if applicable	Needed when relying on documents executed before the father died
SPA or authorization letter, if a representative files	Allows another person to transact, subject to office rules

Fees vary. Expect separate costs for notarization, certified true copies from the LCRO, registration fees, PSA copy issuance, courier fees if requested online, and possible consular fees if abroad.

Common Scenarios and Practical Answers

The father’s name is on the birth certificate, but the child uses the mother’s surname

This is common. If the father validly acknowledged the child, the child may use the father’s surname by filing the AUSF. Without the AUSF, the record may remain under the mother’s surname.

The father signed an acknowledgment after the birth was already registered

Register the acknowledgment with the LCRO where the child’s birth was registered, then file the AUSF if the child will use the father’s surname. PSA specifically recognizes this route for a birth certificate already registered under the mother’s surname. (Philippine Statistics Authority)

The father refuses to acknowledge the child

RA 9255 usually cannot be used administratively without the father’s express acknowledgment or a court judgment. If paternity must be established for support, inheritance, or identity purposes, the remedy may involve court action.

The father is dead

If the father left a valid public document or private handwritten instrument acknowledging the child during his lifetime, that document may still be relevant. PSA rules allow filing of a private handwritten instrument by the mother, the person himself or herself if of age, or the guardian if the father is already deceased, provided supporting documents prove filiation. (Supreme Court E-Library)

If there is no written acknowledgment at all, the family may need court guidance.

The father is a foreigner

A foreign father may acknowledge the child, and the child may use his surname if RA 9255 requirements are met. This does not automatically give the child the father’s citizenship. Citizenship depends on the law of the father’s country and, for Philippine citizenship, on the Philippine Constitution and the citizenship of the parents.

If the child was born abroad to a Filipino parent, the birth is usually reported through a Philippine Embassy or Consulate as a Report of Birth. If the AUSF or acknowledgment is executed abroad, filing through the Philippine Foreign Service Post is usually the most practical route.

The child needs a passport soon

The DFA and Philippine Embassies generally rely on the name appearing in the PSA birth certificate or Report of Birth. For example, Philippine Embassy passport guidance states that the passport name follows the name on the PSA birth certificate. (Philippine Embassy)

If the child’s PSA record is not yet annotated, the passport may be issued under the current PSA name, not the desired father’s surname. For urgent travel, ask the DFA or consulate whether to proceed first under the existing PSA record or wait for annotation.

The parents later married

Using the father’s surname under RA 9255 is different from legitimation.

Legitimation may apply when the parents later validly marry each other and were not legally disqualified to marry at the time of the child’s conception, or were disqualified only because one or both were below 18. RA 9858 amended Articles 177 and 178 of the Family Code on legitimation. (Supreme Court E-Library)

If legitimation applies, the child’s status changes from illegitimate to legitimate by fiction of law. That is a separate civil registry process from RA 9255.

Common Pitfalls That Delay RA 9255 Processing

1. Assuming the father’s name alone is enough

The father’s name appearing on the birth certificate is helpful, but the LCRO must still determine whether there was valid acknowledgment and whether the required documents were properly registered.

2. Filing in the wrong office

If the child was born in Cebu but the family now lives in Quezon City, the RA 9255 documents are usually filed with the LCRO of the child’s place of birth, not simply the place of current residence.

3. Using inconsistent names

Small differences can cause delays, such as:

“Juan Dela Cruz” in one document and “Juan de la Cruz Jr.” in another;
missing middle names;
wrong birth dates;
different spellings of the mother’s maiden surname;
foreign names with suffixes, accents, or multiple surnames.

Correct these before filing or ask the LCRO whether a supplemental report, clerical correction, or court order is needed.

4. Waiting until a passport or visa deadline

RA 9255 annotation is not instant. Even if the LCRO accepts the documents quickly, PSA database annotation and copy issuance can take additional time. Start early if the child needs school enrollment, passport issuance, visa processing, dual citizenship paperwork, or immigration records.

5. Thinking surname use gives the father custody

It does not. Article 176 still places illegitimate children under the parental authority of the mother. The Supreme Court in Grande v. Antonio also confirmed that parental authority and custody over minor illegitimate children belong to the mother unless there are compelling reasons showing she is unfit. (Supreme Court E-Library)

The father may have support obligations and visitation rights, but using his surname does not automatically transfer custody or decision-making authority.

Frequently Asked Questions

Can an illegitimate child use the father’s surname in the Philippines?

Yes. An illegitimate child may use the father’s surname if the father expressly recognized the child and the required AUSF and civil registry documents are properly filed.

Is the father’s consent required?

The father’s express acknowledgment of paternity is required. But the father cannot force the child to use his surname. The Supreme Court has ruled that use of the father’s surname is discretionary for the child.

Can the mother refuse to use the father’s surname for the child?

For very young children, the mother or guardian usually executes the AUSF. If there is a dispute, the father cannot simply compel the change. Courts and civil registrars must respect that the surname issue affects the child’s identity and best interests.

Can an adult illegitimate child change to the father’s surname?

Yes, if the adult child is covered by the RA 9255 rules, the father validly acknowledged the child, and the adult executes the AUSF. This is common for adults fixing PSA records for passports, migration, inheritance, or consistency with long-used names.

Does RA 9255 apply to children born before 2004?

Under the current PSA AO No. 1-2023, the rules apply to non-marital children during the effectivity of the Family Code, including covered births before RA 9255, and the rules have retroactive effect under the amended coverage. This is an important update from older guidance.

What if the father is not listed on the birth certificate?

The child may still use the father’s surname if the father later executes a valid acknowledgment, such as an Affidavit of Admission of Paternity or another accepted public document, and the AUSF is filed.

What if the father refuses to sign anything?

The administrative RA 9255 route will usually not work without voluntary acknowledgment or a court judgment. The possible remedy may be a court action to establish filiation, especially if the issue involves support, inheritance, or legal identity.

Will using the father’s surname make the child legitimate?

No. RA 9255 allows use of the father’s surname, but it does not change the child’s status from illegitimate to legitimate. Legitimation is a separate process, usually involving the parents’ later valid marriage and the requirements under the Family Code as amended by RA 9858.

Does using the father’s surname give the father custody?

No. For illegitimate children, parental authority generally remains with the mother. The father’s acknowledgment may affect support, inheritance, and identity, but it does not automatically give him custody.

How long does the process take?

If documents are complete, the PSA copy issuance or annotation request stage may be processed in several working days under PSA service standards. In practice, the full process may take weeks or longer depending on the LCRO, PSA verification, old records, missing documents, consular transmittal, or inconsistencies in the birth record.

Key Takeaways

An illegitimate child in the Philippines may use the father’s surname if the father expressly acknowledged the child and the proper RA 9255 documents are filed.
The AUSF is required to use the father’s surname; acknowledgment alone usually does not change the surname.
The father cannot force the child to use his surname. The Supreme Court treats the surname choice as the child’s right.
The mother generally retains parental authority over an illegitimate child even if the child uses the father’s surname.
Current PSA rules under AO No. 1-2023 expanded RA 9255 coverage to non-marital children during the effectivity of the Family Code, including covered births before 2004.
File with the correct LCRO or Philippine Embassy/Consulate, and expect delays if records are old, inconsistent, incomplete, or executed abroad.
RA 9255 changes surname use; it does not by itself legitimate the child, grant citizenship, or transfer custody.