Yes. Under Philippine law, an illegitimate child—also called a non-marital child in newer civil-registration issuances—may use the father’s surname when the father has expressly acknowledged paternity and the required civil-registry documents are properly executed and registered. However, using the father’s surname is a choice, not an automatic requirement. The father cannot force the child to use it, and simply writing the father’s name on a hospital form or birth certificate does not always complete the legal process.

When Can an Illegitimate Child Use the Father’s Surname?

The governing rule is Article 176 of the Family Code, as amended by Republic Act No. 9255, which took effect on March 19, 2004.

An illegitimate child may use the father’s surname if the father expressly recognizes the child through any of the following:

The child’s record of birth in the civil register;
A public document, such as a notarized Affidavit of Acknowledgment or Admission of Paternity; or
A private handwritten instrument personally written and signed by the father.

A separate Affidavit to Use the Surname of the Father, commonly called an AUSF, must generally be executed and registered before the father’s surname can be reflected in the civil-registry record. (LawPhil)

If the father has not legally acknowledged the child, the general rule is that the child uses the mother’s surname.

Using the Father’s Surname Is Optional

The word “may” in Article 176 is important. In Grande v. Antonio, the Supreme Court explained that an illegitimate child is permitted—but not compelled—to use the father’s surname. The law gives the child a choice rather than giving the father an absolute right to impose his surname. See the Supreme Court decision in Grande v. Antonio. (LawPhil)

This means:

The child may continue using the mother’s surname even after being acknowledged by the father.
A father cannot unilaterally change the child’s surname.
Recognition of paternity does not automatically change an existing birth certificate.
The AUSF must be executed by the legally authorized person, depending on the child’s age.

Who Signs the Affidavit to Use the Father’s Surname?

The person who executes the AUSF depends on the child’s age at the time the affidavit is made.

Child’s age	Who executes the AUSF?	Important requirement
Below 7 years old	The mother	A guardian may act only when the mother is absent or unable to act under the applicable rules
7 to 17 years old	The child	The mother or guardian must attest that the child knowingly chose to use the father’s surname
18 years old or older	The adult child	The adult child decides and signs without needing the mother’s consent

These rules recognize that an older child has an increasing personal interest in choosing the surname by which he or she will be known. For an adult child, the father or mother generally cannot make the decision on the child’s behalf. (Philippine Statistics Authority)

A child who has been acknowledged by the father may still retain the mother’s surname if no valid AUSF is executed.

Does the Child’s Date of Birth Matter?

Yes. The correct procedure depends partly on when the child was born.

Children Born on or After August 3, 1988

August 3, 1988 is the date the Family Code took effect. Under PSA Administrative Order No. 1, Series of 2023, the administrative procedure under Republic Act No. 9255 now covers non-marital children born during the effectivity of the Family Code, including:

Unregistered births;
Registered births in which the child currently uses the mother’s surname; and
Children born between August 3, 1988 and March 18, 2004.

This is an important update. Older articles and civil-registry guidance often stated that Republic Act No. 9255 could be used only by children born on or after March 19, 2004. That restriction is no longer consistent with the PSA’s revised 2023 rules. The updated coverage is retroactive to births occurring from August 3, 1988 onward. See PSA Memorandum Circular No. 2023-14 and Administrative Order No. 1, Series of 2023.

Children Born Before August 3, 1988

Older births may be governed by the Civil Code rules that applied before the Family Code.

As summarized by the Supreme Court in In re: Petition for Change of Name and/or Correction of Entry in the Civil Registry of Jan Barcelote Tinitigan:

A child acknowledged by both parents principally used the father’s surname.
A child recognized by only one parent used the surname of the recognizing parent.
A child recognized by neither parent used the mother’s surname.

Because the applicable law and the wording of older birth records can differ, the Local Civil Registrar may need to review the original record, the type of acknowledgment, and the law in force when the child was born. See the Supreme Court’s discussion of the pre-Family Code rules. (Supreme Court E-Library)

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

1. Check the Existing Birth Record

Obtain a recent PSA copy or a certified copy from the Local Civil Registry Office, or LCRO, where the birth was registered.

Check whether:

The father’s name appears on the birth certificate;
The father signed the acknowledgment portion;
An Affidavit of Acknowledgment or Admission of Paternity is already attached or registered;
The child currently uses the mother’s surname; and
There are spelling, date, or identity discrepancies in the parents’ records.

The appearance of the father’s name alone is not always sufficient. The record must show a legally valid acknowledgment of paternity.

2. Establish the Father’s Express Acknowledgment

If the father has not yet validly acknowledged the child, he may generally do so through:

The Affidavit of Acknowledgment or Admission of Paternity on the birth record;
A separate notarized public document admitting paternity; or
A private handwritten instrument personally written and signed by him.

A typed document signed by the father may qualify as a public document if properly notarized, but it is not the same as the “private handwritten instrument” specifically mentioned in Article 176. When relying on a private instrument, the safest approach is for the material declaration of paternity to be in the father’s own handwriting.

If the father is available, he should execute the required acknowledgment before a notary public, civil registrar, Philippine consular officer, or another officer authorized under the applicable procedure.

3. Execute the AUSF

The mother, child, or adult child must execute the AUSF according to the age rules discussed above.

The affidavit normally identifies:

The child’s registered name and date and place of birth;
The mother and father;
The document through which the father acknowledged paternity;
The child’s existing surname;
The father’s surname that the child will use; and
The voluntary decision to use that surname under Republic Act No. 9255.

Names must match the supporting civil-registry documents exactly. Differences involving middle names, compound surnames, suffixes, dates, or spelling can delay registration.

4. Register the Documents with the Proper Office

For a Philippine birth and documents executed in the Philippines, file with the Local Civil Registry Office of the city or municipality where the child’s birth was registered.

When the relevant documents are executed abroad, registration may be handled through the appropriate Philippine Foreign Service Post, meaning the Philippine embassy or consulate with jurisdiction over the place where the person resides.

As a rule, the acknowledgment and AUSF should be registered within 20 days from execution. Documents submitted later may still be accepted, but delayed-registration requirements may apply. (Philippine Statistics Authority)

5. Wait for the Birth Record to Be Annotated

The original entry is normally not erased or replaced. Instead, the civil registrar places an annotation stating, in substance, that the child shall be known under the new name pursuant to Republic Act No. 9255.

For example, a birth record originally registered as “Maria Reyes Santos” may be annotated to state that the child shall be known as “Maria Reyes Cruz,” depending on the legally correct treatment of the surname and middle name.

The PSA provides an official process for a birth certificate already registered under the mother’s surname. (Philippine Statistics Authority)

6. Obtain the Annotated PSA Birth Certificate

After the LCRO completes the local annotation, it must endorse or transmit the documents to the Philippine Statistics Authority for central annotation.

A locally annotated certified copy may become available before the PSA database is updated. For passports and many national-level transactions, agencies commonly require the PSA-issued annotated copy.

Review the new PSA copy carefully. Confirm that:

The annotation is readable;
The child’s new full name is stated correctly;
The father’s and mother’s details are consistent;
The middle name is treated correctly; and
No typographical error was introduced during annotation.

7. Update the Child’s Other Records

The civil-registry annotation does not automatically update records held by other agencies and private institutions.

The child or parent may need to present the annotated PSA birth certificate to update:

Philippine passport records;
National ID records;
School and university records;
PhilHealth and other health records;
Bank accounts;
Employment and payroll records;
Insurance policies;
Visa and immigration files; and
Professional licenses.

Keep several certified copies, receipts, registration certificates, and the original acknowledgment documents. Older records under the mother’s surname may also need an affidavit of discrepancy or the receiving agency’s name-alignment form.

Documents Commonly Required

Requirements can vary slightly among local civil registrars, but the usual documents include:

Document	Purpose
PSA or LCRO-certified birth certificate	Shows the child’s current registered name and birth details
Affidavit of Acknowledgment or Admission of Paternity	Establishes the father’s express recognition
Public document or handwritten instrument acknowledging paternity	Alternative legal proof of recognition
Affidavit to Use the Surname of the Father	Records the voluntary decision to use the surname
Valid government-issued IDs	Verifies the identities and signatures of the parties
Certificate of registration of the acknowledgment	Shows that the acknowledgment was registered
Certificate of registration of the AUSF	Shows that the AUSF was registered
Death certificate of the father, when applicable	Supports processing when the father has died
Proof of guardianship or relationship	Required when a guardian is authorized to act
Annotated LCRO copy	Used for endorsement and PSA central annotation

The PSA’s annotation checklist includes the AUSF, acknowledgment documents, certificates of registration, and both the unannotated and locally annotated birth records.

Bring original documents and several photocopies. Some LCROs use their own intake forms and may require personal appearance, specimen signatures, community tax certificates, or additional identification when records are old or inconsistent.

How Long Does the Process Take?

The full process often takes several weeks to a few months, depending on:

Whether the birth is already registered;
Whether the father previously acknowledged the child;
Whether the documents are complete;
The workload of the LCRO;
Whether the record is old, handwritten, damaged, or archived;
How quickly the LCRO transmits the annotated record to the PSA; and
Whether the birth or documents originated abroad.

The PSA’s 2024 Citizen’s Charter lists approximately five working days for premium annotation processing and seven working days for regular processing after complete documents have reached the responsible PSA unit. Those periods do not include the time needed for LCRO registration, local annotation, transmission, correction of deficiencies, or delivery of the resulting PSA copy.

How Much Does It Cost?

There is no single nationwide total.

Possible expenses include:

LCRO registration and annotation fees;
Notarial fees;
Certified-copy fees;
PSA document issuance and delivery fees;
Consular fees for documents executed abroad;
Apostille or authentication expenses;
Translation costs for foreign-language documents; and
Courier charges.

Fees vary by city, municipality, embassy, or consulate. Obtain the current written assessment from the office that will process the application before paying.

What Happens to the Child’s Middle Name?

The middle-name rule is frequently misunderstood.

For a Philippine-born non-marital child:

If the father has not acknowledged the child, the child generally has no middle name and uses the mother’s surname.
If the father has acknowledged the child but no valid AUSF has been registered, the child ordinarily continues using the mother’s surname and generally has no middle name.
If the child validly uses the father’s surname under Republic Act No. 9255, the mother’s maiden surname ordinarily becomes the child’s middle name.

For births registered before February 2, 2007 that already contain a middle name, PSA guidance generally allows the existing entry to continue without requiring correction solely because of the later rules. For children born abroad, the middle name appearing in the foreign civil-registry document may control, subject to Philippine reporting requirements. See PSA Memorandum Circular No. 2020-28.

What Using the Father’s Surname Does—and Does Not—Change

Using the father’s surname changes the child’s registered name. It does not, by itself, change the child’s civil status.

It does not automatically make the child legitimate

The child remains legally classified as illegitimate or non-marital unless the child becomes legitimated under the Family Code or another applicable law.

It does not automatically transfer parental authority

Article 176 generally places parental authority over an illegitimate child with the mother. The use of the father’s surname does not automatically give the father sole or equal custody, nor does it remove the mother’s parental authority. Custody and visitation disputes are decided under separate rules, with the child’s best interests as the central consideration. See Articles 176 and related provisions of the Family Code. (LawPhil)

It does not cancel the father’s duty to provide support

A father’s duty to support a legally recognized child does not depend on whether the child uses his surname. Conversely, using the father’s surname does not by itself prove every element of a support claim if paternity remains disputed.

It does not create citizenship

A foreign father’s surname does not make the child a citizen of the father’s country. Nationality depends on the citizenship laws of the countries concerned and the parents’ citizenship at the relevant time.

It can help document filiation

“Filiation” means the legally recognized parent-child relationship. The acknowledgment documents behind the surname change may be relevant in claims involving support, inheritance, government benefits, and family records. However, the surname alone is not conclusive proof of every legal right.

What If the Father Refuses to Acknowledge the Child?

The administrative Republic Act No. 9255 process generally requires the father’s express recognition.

The following may help prove paternity in a court case, but they do not automatically replace the required civil-registry acknowledgment:

DNA test results;
Photographs;
Messages or emails;
Proof of financial support;
School or medical records identifying the father;
Testimony from relatives or witnesses; or
Evidence that the father openly treated the child as his own.

When the father refuses recognition, the child or mother may need to file an action to establish filiation under Articles 172 and 175 of the Family Code. A court may consider documentary evidence, continuous possession of the status of a child, testimony, and DNA evidence.

Once filiation is judicially established, the court’s order may support the appropriate correction or annotation of the civil-registry record. Time limits can depend on the type of evidence and the circumstances, so delays can seriously complicate a case—especially after the alleged father dies.

What If the Father Is Already Dead?

A deceased father can no longer execute a new acknowledgment.

Processing may still be possible when he acknowledged the child while alive through:

The signed birth record;
A notarized admission of paternity;
A qualifying handwritten instrument;
A will or other public document; or
Another legally recognized record.

Under PSA procedures, the mother, adult child, or guardian may be allowed to submit an existing private handwritten instrument and supporting proof when the father has died. The LCRO will examine whether the document satisfies the legal requirements.

When there is no valid acknowledgment, a judicial filiation case may be necessary. Evidence should be preserved promptly, including handwriting samples, correspondence, family records, photographs, financial records, and information about possible DNA testing involving close relatives.

What If the Mother Was Married to Another Man When the Child Was Born?

This situation cannot usually be solved through a simple AUSF.

A child conceived or born during a valid marriage is generally presumed legitimate in relation to the husband. The mother, biological father, or child cannot simply bypass that presumption by asking the civil registrar to replace the husband’s name or use the alleged biological father’s surname.

The child’s status must first be resolved through the proper direct court action by a legally authorized party and within the applicable period. Legitimacy cannot ordinarily be attacked indirectly through a routine civil-registry petition. The Supreme Court emphasized this principle in Ordoña v. Local Civil Registrar of Pasig City. (LawPhil)

What If the Parents Marry After the Child’s Birth?

The parents’ later marriage may allow legitimation, but this is a separate process from using the father’s surname under Republic Act No. 9255.

Under Articles 177 to 180 of the Family Code, as amended by Republic Act No. 9858, a child may generally be legitimated when:

The parents were legally free to marry each other when the child was conceived; or
Their only impediment was that one or both parents were below the legal age to marry; and
The parents later enter into a valid marriage.

Legitimation generally gives the child the rights of a legitimate child, with effects retroacting to birth. It is usually unavailable when one parent was validly married to another person at the time of conception, because that is a legal impediment beyond minority. (LawPhil)

What If the Father Is a Foreigner or the Child Was Born Abroad?

A foreign father may acknowledge the child, and the child may use his surname if Philippine legal and civil-registration requirements are satisfied.

For a child born abroad to a Filipino parent, the birth is ordinarily reported through the Philippine embassy or consulate with jurisdiction over the place of birth. Depending on the circumstances, the post may require:

The foreign birth certificate;
Report of Birth forms;
The parents’ passports and proof of citizenship;
An Affidavit of Acknowledgment or Admission of Paternity;
An AUSF;
Proof of the parents’ civil status; and
Properly authenticated, apostilled, or translated foreign documents.

Documents executed abroad may be notarized before a Philippine consular officer. A document notarized by a foreign notary may require an apostille if issued in an Apostille Convention country, or another form of authentication if the issuing country does not participate. Requirements vary by foreign service post, so the post’s current checklist should be followed. The DFA publishes a sample Affidavit of Acknowledgment of Paternity and Consent to Use the Father’s Surname. (Philippine Embassy in New Delhi)

Common Mistakes That Delay or Derail the Application

Assuming that listing the father’s name is enough. The birth record must contain a valid acknowledgment or be supported by a legally sufficient acknowledgment document.
Submitting only an AUSF. The AUSF does not replace the father’s recognition of paternity.
Letting the father decide for an adult child. Once the child is 18, the adult child must personally choose and execute the AUSF.
Using inconsistent names. Differences in spelling, suffixes, middle names, citizenship, dates, or places of birth commonly result in requests for additional documents.
Using the new surname before annotation. This can create mismatches among school, passport, banking, and government records.
Waiting until the father dies. Death may remove the easiest route—his personal execution of an acknowledgment.
Using the wrong procedure. Republic Act No. 9255 is different from administrative correction under Republic Act No. 9048 or Republic Act No. 10172 and from a judicial Rule 108 proceeding.
Relying on outdated pre-2023 advice. Children born from August 3, 1988 onward may now fall within the revised administrative coverage even if they were born before Republic Act No. 9255 took effect.

Frequently Asked Questions

Can an illegitimate child automatically use the father’s surname?

No. The father must first expressly acknowledge paternity through a legally accepted document, and a valid AUSF must ordinarily be executed and registered. The birth record must then be annotated.

Can the father force the child to use his surname?

No. The Supreme Court has ruled that use of the father’s surname is optional. For an adult child, the decision belongs to the adult child.

Can the mother use the father’s surname for the child without the father’s signature?

Generally, not through the ordinary Republic Act No. 9255 administrative process unless the father previously made a valid acknowledgment in another legally accepted document. If paternity has never been acknowledged and the father refuses, court action may be necessary.

Is a DNA test enough to change the child’s surname?

Not by itself in a routine LCRO application. A voluntary acknowledgment is normally required. When paternity is contested, DNA evidence may be presented in a judicial filiation case.

Can an adult illegitimate child still use the father’s surname?

Yes. An adult child may personally execute the AUSF if the father’s acknowledgment satisfies the law. The mother’s consent is not required merely because the child is already an adult.

Can a child born before March 19, 2004 use the father’s surname?

Yes, potentially. Under the PSA’s 2023 revised rules, non-marital children born from August 3, 1988 onward may use the administrative procedure if the legal requirements are met. Births before August 3, 1988 require review under the older law.

Does the child become legitimate after using the father’s surname?

No. The surname change does not alter legitimacy. Legitimation requires separate legal conditions, usually including a valid subsequent marriage between parents who were legally qualified to marry each other when the child was conceived.

Who has custody after the child uses the father’s surname?

The surname change does not automatically change custody or parental authority. Under Article 176, the mother generally exercises parental authority over an illegitimate child, subject to court orders and the child’s best interests.

Can the child go back to using the mother’s surname?

A later change is not necessarily accomplished by simply withdrawing the AUSF. Once the civil-registry record has been annotated and the new name is being used, another administrative or judicial name-change procedure may be required depending on the record and the reason for the request.

Will the PSA issue an entirely new birth certificate?

The original civil-registry entry is generally preserved. The PSA issues a copy bearing an annotation showing the name by which the child shall be known under Republic Act No. 9255.

Key Takeaways

An illegitimate child may use the father’s surname only when the father has legally acknowledged paternity and the required AUSF is properly registered.
Using the father’s surname is optional; the father cannot impose it on the child.
The person who signs the AUSF depends on whether the child is below 7, between 7 and 17, or already 18.
Current PSA rules cover qualifying children born from August 3, 1988 onward, including those born before Republic Act No. 9255 took effect.
The process normally involves the LCRO or Philippine embassy or consulate, followed by annotation in the PSA’s central records.
Using the father’s surname does not by itself make the child legitimate, transfer custody, create citizenship, or determine all inheritance rights.
Cases involving disputed paternity, a deceased father, a married mother, or inconsistent civil-registry records may require additional evidence or court proceedings.