I. Introduction

In the Philippines, a child’s surname is not merely a matter of personal identity. It is also tied to civil status, filiation, parental authority, inheritance, school records, passports, government identification, and other legal documents. For an illegitimate child, the question of what surname may be used is governed by the Family Code, civil registry laws, administrative issuances of the Philippine Statistics Authority and the Civil Registrar General, and relevant jurisprudence.

The basic rule is that an illegitimate child uses the surname of the mother. However, Philippine law allows an illegitimate child to use the surname of the father if the child’s filiation has been expressly recognized by the father in the manner required by law. This does not automatically convert the child into a legitimate child. The use of the father’s surname is a matter of surname usage and civil registry annotation, not legitimation.

Changing an illegitimate child’s surname on a birth certificate therefore depends on the factual and legal situation: whether the father acknowledged the child, whether the birth certificate already contains paternal information, whether the child is a minor or of age, whether the requested change is clerical or substantial, and whether the change is from the mother’s surname to the father’s surname, from the father’s surname back to the mother’s surname, or to another surname altogether.

II. Legal Status of an Illegitimate Child

Under Philippine family law, children are generally classified as legitimate or illegitimate.

A child is legitimate if conceived or born during a valid marriage of the parents, subject to specific rules under the Family Code. A child is illegitimate if conceived and born outside a valid marriage, unless otherwise provided by law.

Illegitimate status affects several legal consequences, including surname, parental authority, custody, and succession. However, illegitimacy does not deprive the child of legal personality, civil rights, support, identity, and the right to establish filiation.

For purposes of surname, the core statutory provision is Article 176 of the Family Code, as amended by Republic Act No. 9255.

III. General Rule: An Illegitimate Child Uses the Mother’s Surname

The general rule is that an illegitimate child shall use the surname of the mother.

This reflects the legal principle that maternity is usually established by the fact of birth, while paternity must be established through recognition, admission, proof, or other legally accepted means. If the father has not recognized the child, the child’s surname on the birth certificate should ordinarily be the mother’s surname.

For example, if the mother is Maria Santos and the father has not validly acknowledged the child, the child’s registered surname would generally be Santos.

IV. Exception: Use of the Father’s Surname Under Republic Act No. 9255

Republic Act No. 9255 amended Article 176 of the Family Code. It allows illegitimate children to use the surname of their father if their filiation has been expressly recognized by the father.

The law does not make the use of the father’s surname automatic. Recognition by the father is required.

The law also does not legitimate the child. The child remains illegitimate unless legitimated by a subsequent valid marriage of the parents under the rules on legitimation, or unless another law applies. The effect of RA 9255 is limited to allowing the child to use the father’s surname upon compliance with legal requirements.

V. Recognition of Paternity: What Is Required?

For an illegitimate child to use the father’s surname, the father must expressly recognize the child. Recognition may appear in any of the following:

The record of birth appearing in the civil register;
A public document;
A private handwritten instrument signed by the father.

The birth certificate itself may serve as recognition if the father signed the birth certificate or if the facts show that he expressly acknowledged the child in the civil registry record.

A public document may include an affidavit of admission of paternity, a notarized document, or another formal instrument where the father clearly admits that he is the father of the child.

A private handwritten instrument may be sufficient if it is written and signed by the father and clearly admits paternity. However, civil registry offices often require authentication or supporting documents before allowing annotation or registration based on such instrument.

VI. Affidavit to Use the Surname of the Father

The administrative process usually involves an Affidavit to Use the Surname of the Father, commonly referred to as an AUSF.

The AUSF is the document used to implement RA 9255 in the civil registry record. It is not the same as legitimation. It is an affidavit that allows the illegitimate child to use the father’s surname once paternity has been acknowledged.

Depending on the situation, the AUSF may be executed by:

The mother, if the child is still a minor;
The guardian, in proper cases;
The child, if already of legal age;
The father, in connection with his admission of paternity or acknowledgment.

Where the father has already acknowledged the child in the birth certificate, the AUSF may be filed to annotate the child’s use of the father’s surname. Where the father did not sign the birth certificate, a separate affidavit of admission of paternity or other legally acceptable proof may be required.

VII. Effect on the Birth Certificate

When the requirements are met, the civil registrar does not usually erase the original entries in the birth certificate. Instead, the civil registry record is annotated.

The annotation may state that the child is allowed to use the surname of the father pursuant to RA 9255. The child’s name may then appear in later certified copies according to the annotated surname arrangement.

This distinction is important. The civil registry record is a permanent public record. Changes are generally made by annotation, not by physically deleting or rewriting the original entry.

VIII. Change From Mother’s Surname to Father’s Surname

This is the most common situation.

An illegitimate child was registered using the mother’s surname. Later, the father acknowledges the child. The family then wants the child to use the father’s surname.

This may usually be done administratively if the father validly acknowledges the child and the proper documents are submitted to the local civil registrar.

Common requirements may include:

Certified true copy of the child’s birth certificate;
Affidavit to Use the Surname of the Father;
Affidavit of Admission of Paternity, if recognition is not already shown in the birth certificate;
Valid identification documents of the parties;
Proof of authority of the person executing the affidavit, if applicable;
Other documents required by the local civil registrar or the Philippine Statistics Authority.

If approved, the birth certificate is annotated to reflect the child’s use of the father’s surname.

IX. When the Father Signed the Birth Certificate

If the father signed the birth certificate at the time of registration, his signature may constitute recognition of paternity. In that case, the process is generally simpler because the acknowledgment already appears in the record of birth.

However, the child’s surname may still not automatically change if the child was originally registered under the mother’s surname. The AUSF or equivalent documentary compliance may still be required to authorize the use of the father’s surname.

The key point is that recognition and surname usage are related but distinct. Recognition establishes the legal basis. The AUSF implements the use of the surname.

X. When the Father Did Not Sign the Birth Certificate

If the father did not sign the birth certificate, the child generally cannot simply adopt the father’s surname without proof of paternal recognition.

A separate document admitting paternity may be required. This is often an Affidavit of Admission of Paternity or Acknowledgment. It should clearly state that the man recognizes the child as his own.

If the father refuses to acknowledge the child, the child or the mother may have to establish filiation through judicial action or other legally accepted proof. In that situation, an administrative surname change may not be enough.

XI. When the Father Is Unknown or Refuses to Recognize the Child

If the father is unknown, unavailable, or refuses to acknowledge the child, the child generally uses the mother’s surname.

The mother cannot unilaterally place a man’s name as father and cause the child to use his surname without lawful acknowledgment or proof. Paternity has legal consequences, including support, succession, and civil status records. Because of this, civil registrars require compliance with rules on recognition.

If paternity is disputed, the remedy is usually judicial, not merely administrative.

XII. Change From Father’s Surname Back to Mother’s Surname

A more complicated issue arises when an illegitimate child has already been registered using the father’s surname and later wants to use the mother’s surname.

This may happen because the father abandoned the child, the father’s acknowledgment is being questioned, the child has long used the mother’s surname, or the child personally prefers the mother’s surname.

Unlike the change from the mother’s surname to the father’s surname under RA 9255, changing from the father’s surname back to the mother’s surname may be treated as a substantial change. It may require a court petition, especially if the requested change affects filiation, identity, or the child’s registered civil status.

The reason is that a surname is an important legal identifier. Once the birth certificate has been registered and annotated, civil registry entries cannot be changed casually. Administrative correction is generally limited to clerical or typographical errors and certain specified changes allowed by law.

XIII. Is the Use of the Father’s Surname Mandatory?

No. Philippine jurisprudence has recognized that the use of the father’s surname by an illegitimate child under RA 9255 is permissive, not mandatory.

The law says that illegitimate children “may” use the surname of the father if filiation has been expressly recognized. The word “may” indicates permission, not compulsion.

This means that even if the father acknowledges the child, the child is not necessarily forced to use the father’s surname. The child may continue using the mother’s surname, especially where circumstances justify it.

This principle is particularly important in cases where the father recognizes the child late, has not supported the child, or where the child has already established identity using the mother’s surname.

XIV. Administrative Correction Versus Judicial Change of Name

Changing a birth certificate can be administrative or judicial.

Administrative correction is allowed for limited cases, such as clerical or typographical errors, and certain changes under Republic Act No. 9048, as amended by Republic Act No. 10172. These laws allow correction of specific civil registry entries without going to court, such as typographical errors, changes in first name or nickname under certain grounds, correction of sex if it is a clerical error, and correction of day or month of birth.

However, a change of surname is generally substantial. Substantial changes usually require a judicial petition under Rule 103 or Rule 108 of the Rules of Court, depending on the nature of the correction.

A surname change is not usually considered a mere clerical error unless the issue is plainly typographical, such as a misspelling that does not affect identity or filiation.

XV. Rule 103: Change of Name

Rule 103 of the Rules of Court governs petitions for change of name.

A person may seek a legal change of name for proper and reasonable cause. Courts have recognized grounds such as:

The name is ridiculous, dishonorable, or difficult to write or pronounce;
The change is necessary to avoid confusion;
The person has continuously used and been known by another name;
The change will avoid prejudice or improve legal identity;
Other compelling reasons recognized by law and jurisprudence.

A change of surname under Rule 103 is a judicial proceeding. It requires filing a petition in court, publication, notice, and an opportunity for the government and interested parties to oppose.

For an illegitimate child, Rule 103 may be relevant when the requested surname change is not covered by RA 9255 or cannot be done administratively.

XVI. Rule 108: Cancellation or Correction of Entries in the Civil Registry

Rule 108 governs cancellation or correction of entries in the civil registry.

It may apply when the correction involves entries such as birth, legitimacy, filiation, parentage, or other civil status details. If the requested change affects paternity or legitimacy, Rule 108 is often the more appropriate remedy.

Rule 108 may be summary if the correction is clerical. But if the correction is substantial or controversial, the proceeding becomes adversarial. This means that all affected parties must be notified and given the opportunity to participate.

For example, deleting the name of the father, changing the child’s surname because paternity is disputed, or altering entries that affect filiation may require a Rule 108 proceeding.

XVII. RA 9048 and RA 10172: Administrative Corrections

Republic Act No. 9048, as amended by Republic Act No. 10172, allows certain corrections in the civil registry without a court order.

These laws cover limited administrative corrections, such as:

Clerical or typographical errors;
Change of first name or nickname under allowed grounds;
Correction of day and month of birth;
Correction of sex, if the error is clerical or typographical and not due to sex reassignment or a disputed medical issue.

These laws do not generally allow a full change of surname as a simple administrative correction. Therefore, changing an illegitimate child’s surname often cannot rely solely on RA 9048 or RA 10172 unless the problem is merely typographical.

XVIII. Legitimation Is Different From Use of Father’s Surname

Legitimation is a separate legal concept.

An illegitimate child may be legitimated if the parents were not legally disqualified from marrying each other at the time of the child’s conception and they subsequently enter into a valid marriage. When legitimation occurs, the child becomes legitimate by operation of law, subject to registration requirements.

Legitimation affects the child’s status, surname, parental authority, and inheritance rights as a legitimate child.

By contrast, use of the father’s surname under RA 9255 does not make the child legitimate. The child remains illegitimate but is allowed to use the father’s surname because paternity has been recognized.

This distinction is crucial. A birth certificate annotated under RA 9255 should not be confused with a birth certificate annotated for legitimation.

XIX. Adoption Is Also Different

Adoption is another separate legal process.

If a child is adopted, the child’s surname and legal relationship with the adoptive parent or parents may change according to adoption law. Adoption creates a legal parent-child relationship between the adopter and the adoptee.

Changing an illegitimate child’s surname through adoption is not the same as allowing the child to use the biological father’s surname under RA 9255.

Adoption requires a formal legal process and approval by the proper authority or court, depending on the applicable law and type of adoption.

XX. Rights of the Illegitimate Child After Using the Father’s Surname

The use of the father’s surname may help reflect paternal recognition, but it does not by itself give the child the status of a legitimate child.

The child remains entitled to rights as an illegitimate child, including:

The right to support from the father;
The right to use the father’s surname if legally recognized;
The right to inherit from the father as an illegitimate child;
The right to establish filiation;
The right to identity and civil registry documentation.

However, the legitime of an illegitimate child is generally different from that of a legitimate child under succession law.

XXI. Who May File or Execute the Documents?

The person who may initiate or execute documents depends on the child’s age and situation.

If the child is a minor, the mother usually acts on behalf of the child. If another person has legal guardianship, that person may act where appropriate. If the child is of legal age, the child may personally execute the affidavit or file the relevant petition.

The father’s participation is important if the issue is acknowledgment. Without his admission, or without another legal basis to establish filiation, the child generally cannot simply be registered under his surname.

XXII. Practical Procedure for Using the Father’s Surname

The usual administrative route may proceed as follows:

First, secure a certified copy of the child’s birth certificate from the Philippine Statistics Authority or the local civil registrar.

Second, check whether the father acknowledged the child in the birth certificate. Look for the father’s name, signature, and any acknowledgment portion.

Third, prepare the Affidavit to Use the Surname of the Father. If the father did not acknowledge the child in the birth record, prepare or secure an Affidavit of Admission of Paternity or other legally acceptable proof.

Fourth, submit the documents to the local civil registry office where the birth was registered. If the child was born abroad and reported to a Philippine consulate, the procedure may involve the Philippine foreign service post and the civil registry system.

Fifth, wait for the annotation and endorsement to the Philippine Statistics Authority.

Sixth, request an updated PSA copy reflecting the annotation.

Actual documentary requirements may vary depending on the civil registrar, the age of the child, the completeness of the birth record, and whether the father is available.

XXIII. Common Scenarios

1. Child was registered under the mother’s surname; father later signs an acknowledgment.

The child may be allowed to use the father’s surname through RA 9255 compliance, usually by filing an AUSF and proof of acknowledgment.

2. Child was registered under the mother’s surname; father refuses to acknowledge the child.

Administrative change to the father’s surname is generally not available. Filiation must first be established through legally acceptable means.

3. Child was registered under the father’s surname but father and mother were never married.

The child may have been acknowledged. The use of the father’s surname does not make the child legitimate.

4. Child was registered under the father’s surname but now wants to use the mother’s surname.

This may require judicial action, especially if the requested change is substantial or affects the civil registry record.

5. Father’s surname is misspelled.

If the error is purely clerical or typographical, administrative correction may be possible under RA 9048. If the correction affects identity or filiation, court action may be required.

6. Father’s name was entered without his consent.

This may involve a substantial correction of the birth record. A court proceeding under Rule 108 may be required, especially because paternity and civil status are affected.

7. Child is already an adult and wants to use the father’s surname.

The adult child may execute the required affidavit, provided the father’s paternity was legally acknowledged or can be established.

XXIV. Use of Middle Name by an Illegitimate Child

A related issue is the middle name.

In Philippine naming practice, a legitimate child usually uses the mother’s maiden surname as middle name and the father’s surname as surname.

For illegitimate children, the treatment of the middle name can be more complex. If the child uses the mother’s surname as surname, the child may have no middle name in the conventional sense. If the child is allowed to use the father’s surname under RA 9255, civil registry rules may determine whether the mother’s surname appears as the middle name.

In practice, civil registry implementation should be checked carefully because the naming format must match PSA rules and the specific annotation made on the record.

XXV. Effect on School Records, Passport, and Government IDs

Once the birth certificate is annotated, the child’s other records may also need to be updated.

These may include:

School records;
Baptismal or religious records, if relevant;
Philippine passport;
National ID;
PhilHealth, SSS, GSIS, Pag-IBIG, or other government records;
Bank records;
Medical records;
Immigration or travel records.

Government agencies usually rely heavily on the PSA-issued birth certificate. Therefore, the annotated PSA copy is often the primary document used to update other records.

XXVI. Court Proceedings: When They Become Necessary

Court proceedings may be necessary when:

The change is substantial and not merely clerical;
Paternity is disputed;
The father’s name is to be deleted or changed;
The child seeks to stop using the father’s surname after prior registration;
The correction affects legitimacy, filiation, or civil status;
The civil registrar refuses administrative correction;
There are conflicting records;
The requested change is not covered by RA 9255, RA 9048, or RA 10172.

Court proceedings are more formal, more time-consuming, and more expensive than administrative remedies. They also involve publication and notice requirements because civil status records affect public interest.

XXVII. Best Interests of the Child

In cases involving minors, the best interests of the child are highly relevant.

A surname change should not be treated only as a parental preference. The child’s welfare, identity, emotional development, social usage of the name, and legal security matter.

Where the child has long used a particular surname, courts may consider whether changing it would cause confusion or prejudice. Where the father has not supported or has abandoned the child, courts may also consider whether requiring the child to use the father’s surname is appropriate.

The permissive nature of RA 9255 supports the view that the child’s welfare and identity should be respected.

XXVIII. Important Jurisprudential Principle

Philippine jurisprudence has recognized that an illegitimate child’s use of the father’s surname under RA 9255 is not compulsory. The law grants an option. It does not impose an obligation.

This is significant because some fathers mistakenly believe that recognition automatically gives them the right to force the child to carry their surname. Likewise, some families mistakenly believe that acknowledgment automatically changes the child’s birth certificate.

The law permits the use of the father’s surname if the legal requirements are met, but the child’s existing identity and best interests remain important.

XXIX. Common Misconceptions

Misconception 1: If the father signs the birth certificate, the child becomes legitimate.

False. Signing the birth certificate may establish acknowledgment, but it does not make the child legitimate.

Misconception 2: RA 9255 changes the child’s status.

False. RA 9255 allows use of the father’s surname. It does not change illegitimate status.

Misconception 3: The mother can put any father’s surname on the birth certificate.

False. The father must acknowledge the child, or paternity must be legally established.

Misconception 4: A surname can always be changed administratively.

False. Many surname changes are substantial and require court approval.

Misconception 5: Once the father acknowledges the child, the child must use his surname.

False. The use of the father’s surname is generally permissive, not mandatory.

Misconception 6: A corrected birth certificate erases the old record.

False. Civil registry corrections are often made by annotation. The original entry remains part of the record.

XXX. Documentary Checklist

For an administrative RA 9255 process, the following documents are commonly relevant:

PSA-issued birth certificate;
Local civil registrar copy of the birth certificate;
Affidavit to Use the Surname of the Father;
Affidavit of Admission of Paternity, if needed;
Valid IDs of the mother, father, child, or guardian, as applicable;
Proof of the child’s identity;
Proof of authority of the guardian, if applicable;
Other documents required by the local civil registrar.

For judicial proceedings, documents may include:

PSA birth certificate;
Local civil registry records;
School records;
Baptismal certificate or religious records;
Government IDs;
Affidavits of witnesses;
Proof of actual use of the requested name;
Evidence of acknowledgment or non-acknowledgment;
Evidence showing why the change is necessary;
Other documents required by counsel or the court.

XXXI. Choosing the Proper Remedy

The correct remedy depends on the nature of the requested change.

If the child is illegitimate, currently uses the mother’s surname, and the father has acknowledged the child, the usual remedy is administrative annotation under RA 9255.

If the issue is a typographical error, the remedy may be administrative correction under RA 9048 or RA 10172.

If the issue involves changing the surname in a substantial way, deleting or altering paternal details, disputing paternity, or changing civil status entries, the remedy is likely judicial under Rule 103 or Rule 108.

If the parents later married and the child qualifies for legitimation, the remedy may be registration of legitimation, not merely RA 9255.

If the child is adopted, the remedy follows adoption law and the rules on amended birth certificates for adopted children.

XXXII. Legal Effects of the Annotation

Once the civil registry record is annotated, the child may use the father’s surname in official records. The annotated PSA birth certificate becomes the primary evidence for updating other documents.

However, the annotation does not erase illegitimacy. It does not automatically grant the father custody. It does not automatically give the father parental authority over an illegitimate child. Under Philippine law, parental authority over an illegitimate child generally belongs to the mother, subject to relevant rules and court orders.

The father’s recognition may, however, support claims involving support, visitation, inheritance, and proof of filiation.

XXXIII. Parental Authority and Custody

The use of the father’s surname should not be confused with custody.

Even if an illegitimate child uses the father’s surname, parental authority over the illegitimate child generally remains with the mother. The father’s acknowledgment does not automatically transfer custody or parental authority to him.

The father may have obligations, particularly support, and may seek visitation or other relief through proper legal channels. But surname usage alone does not determine custody.

XXXIV. Support and Succession

Recognition of an illegitimate child is important because it may support the child’s right to receive support from the father and to inherit from him as an illegitimate child.

The use of the father’s surname may serve as evidence of recognition, but support and succession depend on the broader legal rules on filiation and family rights.

A father cannot avoid support simply because the child uses the mother’s surname. Conversely, the child’s use of the father’s surname does not make the child legitimate or give the child the same hereditary share as a legitimate child.

XXXV. When the Child Was Born Abroad

If the child was born abroad to a Filipino parent and the birth was reported to a Philippine embassy or consulate, the civil registry process may involve the Report of Birth and later transmittal to the Philippine civil registry system.

The same substantive principles on illegitimacy, acknowledgment, and surname may apply, but the procedure can involve the foreign service post, the Department of Foreign Affairs, and the PSA.

In such cases, consistency between the foreign birth record, Report of Birth, Philippine passport, and PSA record becomes especially important.

XXXVI. Practical Risks and Problems

Several practical problems commonly arise:

The father’s name appears on the birth certificate but there is no signature;
The father signed a document but the civil registrar does not accept it as sufficient;
The child has school records under one surname and a birth certificate under another;
The mother wants to remove the father’s surname because of abandonment;
The father wants the child to use his surname against the mother’s wishes;
The child is already an adult and has used a different surname for many years;
The PSA copy does not yet reflect the local civil registrar’s annotation;
The annotation exists but other agencies refuse to update their records without additional documents.

These problems show why the exact wording of the birth certificate, acknowledgment document, and civil registry annotation matters.

XXXVII. Legal Article Summary

In the Philippines, an illegitimate child generally uses the mother’s surname. Under RA 9255, the child may use the father’s surname if the father has expressly recognized the child. This is usually implemented through an Affidavit to Use the Surname of the Father and civil registry annotation.

The process is administrative when the requirements are straightforward and paternity is properly acknowledged. It becomes judicial when the requested change is substantial, disputed, or affects filiation, legitimacy, or civil status.

Using the father’s surname does not legitimate the child. It does not automatically alter custody, parental authority, or the child’s civil status. It simply allows the child to use the father’s surname based on recognized paternity.

The most important distinctions are these:

Situation	Usual Remedy
Illegitimate child uses mother’s surname and father acknowledges child	RA 9255 / AUSF administrative annotation
Father’s surname or child’s name has a typographical error	RA 9048 or RA 10172, if purely clerical
Child wants to change from father’s surname back to mother’s surname	Usually judicial, depending on facts
Paternity is disputed	Judicial proceeding
Father’s name must be deleted or changed	Usually Rule 108
Child seeks a general legal change of surname	Usually Rule 103
Parents later validly marry and child qualifies	Legitimation process
Child is adopted	Adoption process

XXXVIII. Conclusion

Changing an illegitimate child’s surname on a Philippine birth certificate requires identifying the legal basis for the change. The simplest case is where the child uses the mother’s surname and the father has validly acknowledged the child; in that situation, RA 9255 may allow the child to use the father’s surname through administrative annotation.

More complex cases require greater care. A change involving paternity, deletion of a father’s name, reversal from the father’s surname to the mother’s surname, or disputed filiation may require a court proceeding. The controlling principle is that civil registry records are public records of legal identity and civil status. They cannot be altered merely by preference, convenience, or private agreement.

The surname of an illegitimate child is therefore governed by a balance of rules: the mother’s surname as the default, the father’s surname as a permitted option upon recognition, administrative remedies for limited cases, and judicial proceedings for substantial changes.