1. Why the Child’s Surname Matters

In Philippine law, a child’s surname is more than a label. It is closely tied to:

Filiation (whether the child is legitimate or illegitimate)
Parental authority
Succession rights
Civil status records (birth certificates, passports, school records, etc.)

Because of this, changing a child’s surname—especially to the biological father’s—must follow specific legal rules and procedures.

This article focuses on Philippine law and explains, in a structured way, how and when a child’s surname can be changed to the biological father’s.

2. Legal Bases

Key laws and rules you’ll see mentioned in this context:

Civil Code of the Philippines
Family Code of the Philippines
- Article 174 – surname of legitimate children
- Article 176 – surname of illegitimate children (as amended)
Republic Act No. 9255 – allows certain illegitimate children to use the father’s surname
R.A. 9048 (as amended) – administrative correction of clerical errors and change of first name
R.A. 9858 – legitimation of children born to parents who could have married at the time of conception
Rules of Court
- Rule 103 – Change of Name (judicial)
- Rule 108 – Cancellation or Correction of Entries in the Civil Registry (judicial)

Supreme Court decisions also clarify how these provisions should be understood, especially regarding legitimacy, parental authority, and surnames.

3. Basic Rules on the Child’s Surname

3.1 Legitimate Children

A legitimate child is typically one:

Conceived or born during a valid marriage of the parents; or
Legitimated by subsequent marriage of the parents (under certain conditions).

As a general rule:

Legitimate children bear the father’s surname.

This is anchored in the Civil Code and the Family Code provisions on legitimacy and surnames.

3.2 Illegitimate Children (Before and After R.A. 9255)

Originally, Article 176 of the Family Code provided that:

Illegitimate children use the mother’s surname.

After R.A. 9255 (which amended Article 176):

Illegitimate children shall still use the mother’s surname,
But they may use the father’s surname if filiation has been expressly recognized by the father in specific ways, and subject to the conditions and procedures laid down in the law and its rules.

Important: Using the father’s surname does not make the child legitimate. Legitimacy or illegitimacy is a separate legal status.

4. First Question: Is the Child Legitimate or Illegitimate?

Before talking about “changing” a surname to the biological father’s, you must classify the child’s status:

Legitimate child (parents were validly married at the time of conception/birth, or child was later legitimated)
Illegitimate child (parents not married to each other and not legitimated; or legitimacy has been judicially disproved)

This classification determines:

Whether the law already requires the father’s surname; or
Whether R.A. 9255 procedures apply; or
Whether a court petition is required.

5. Situations Involving Legitimate Children

5.1 Child Already Uses Father’s Surname

If the child is legitimate and the birth certificate already reflects the father’s surname, no change is needed. Issues more often arise when:

The child was erroneously registered under the mother’s surname; or
The legitimacy/filiation entries in the birth certificate are wrong or incomplete.

5.2 Legitimate Child Registered Under Mother’s Surname

Sometimes, a child is legitimate in law (because parents were married at the time of birth), but the birth certificate:

Shows the mother’s surname; or
Indicates the child as illegitimate.

Here, you’re not simply “changing the surname”; you’re correcting the child’s civil status and filiation.

In such cases, the usual approach involves:

Judicial correction under Rule 108 (cancellation or correction of entries), because:
- Changes affecting civil status, filiation, or legitimacy are generally considered substantial, not clerical;
- They usually cannot be done through simple administrative corrections.

The court may order the correction of the birth certificate so that:

The child is recognized as legitimate, and
The surname is corrected to the father’s surname.

This is a full-blown court petition, with notice and publication.

6. Illegitimate Children and R.A. 9255

For illegitimate children, the key is R.A. 9255 and its implementing rules.

6.1 General Rule

Illegitimate children still use the mother’s surname as the default.
They may use the father’s surname if two conditions are met:
1. Filiation is established in the manner required by law;
2. The requirements/procedure under R.A. 9255 and its rules are complied with.

6.2 How Is Filiation with the Father Established?

Typical ways include:

The father is named in the birth certificate, and he signed it; or
An Affidavit of Acknowledgment/Admission of Paternity (or similar public document) was executed by the father; or
A private handwritten instrument signed by the father acknowledging the child; or
A court decision declaring the child as the father’s child.

Without proper legal proof of filiation, the civil registrar cannot allow the child to use the father’s surname under R.A. 9255.

6.3 Who May Apply to Use the Father’s Surname?

This depends on the child’s age:

Child below 7 years old
- The mother, as the parent with parental authority, usually applies on behalf of the child.
- The father’s recognition must already be in acceptable form (birth certificate, affidavit, etc.).
- Some rules also require the father’s express consent embedded in or evidenced by these documents.
Child 7 to below 18 years old
- The mother still acts for the child, but
- The law/rules require the child’s written consent to use the father’s surname.
Child 18 years or older
- The child can apply personally.
- If the father has already acknowledged the child in a manner recognized by law, the adult child can apply to use the father’s surname, even without a new consent document from the father (because filiation is already established).

The precise documentary requirements and forms (like the Affidavit to Use the Surname of the Father, or AUSF) are set out in the implementing rules and civil registry practice.

6.4 Where Is the Application Filed?

Typically:

At the Local Civil Registry Office (LCRO) where the child’s birth was recorded; or
At the LCRO of the child’s residence, which will coordinate with the LCRO where the birth is registered;
For births abroad: at the Philippine Consulate/Embassy where the birth was reported, depending on the rules at the time.

The LCRO then forwards the approved documents for annotation to the Philippine Statistics Authority (PSA), so future PSA-issued birth certificates bear the annotation that the child is allowed to use the father’s surname under R.A. 9255.

6.5 What Actually Changes?

Once properly processed:

The child’s birth certificate is annotated (not erased and rewritten) to show that they are allowed to use the father’s surname.
The child may then use the father’s surname in:
- School records
- Passport and government IDs
- Other civil registry documents that must be consistent

6.6 Important: Illegitimacy Remains

Even when an illegitimate child uses the father’s surname under R.A. 9255:

The child remains illegitimate (not converted into a legitimate child).
The default rule on parental authority over an illegitimate child is still that the mother has sole parental authority, unless there’s a contrary court ruling.
In succession, the child has the rights of an illegitimate child, not those of a legitimate child (for instance, the share in inheritance is generally different), though filiation being established gives them definite inheritance rights.

Surname is about name, not status.

7. When R.A. 9255 Does Not Apply or Is Not Enough

There are many situations where an administrative R.A. 9255 procedure isn’t available or isn’t sufficient.

7.1 No Valid Proof of Filiation

If:

The father never signed the birth certificate;
There is no notarized or public document acknowledging the child;
There is no private handwritten acknowledgment; and
No court decision has yet declared the filiation,

then civil registry officials cannot simply allow the child to use the father’s surname.

The usual path:

File a court case for compulsory recognition of filiation, often joined with:
- A petition for change of surname (Rule 103), and/or
- A petition for correction of civil registry entries (Rule 108).

Only when the court establishes filiation can the surname then legally be changed or corrected in the civil registry records.

7.2 Dispute About Paternity

If the alleged father denies paternity:

The LCRO cannot treat the matter as a simple administrative change.
The issue becomes a factual and legal dispute about filiation.
This requires a judicial case, where evidence (including possibly DNA testing) can be presented.

7.3 Desire to Change More Than Just Surname (e.g., Status or Legitimacy)

If the objective is:

Not just the surname, but also to have the child declared legitimate or legitimated, or
To change entries on marital status of parents, legitimacy of child, date of marriage, etc.,

then a Rule 108 petition (correction of civil registry entries) or a legitimation proceeding under R.A. 9858 is usually needed, not just R.A. 9255.

8. Legitimation and Its Effect on Surname (R.A. 9858)

Legitimation is a legal process where an illegitimate child becomes legitimate by the subsequent valid marriage of the parents, if no legal impediment existed at the time of the child’s conception.

When legitimation applies:

The child’s status changes from illegitimate to legitimate.
The child is then entitled to all rights of a legitimate child, including:
- Full successional rights;
- Use of the father’s surname as of right.

The procedure usually involves:

Filing documents with the civil registrar and/or a petition with the court, depending on the specifics and timing;
Correcting/annotating civil registry records to reflect the legitimation and the change in surname/status.

9. Judicial Change of Surname (Rule 103)

When the change of surname cannot be done administratively, a judicial petition under Rule 103 of the Rules of Court may be necessary.

9.1 When Is Rule 103 Used?

Examples:

When a legitimate child wants to shift from the father’s surname to the mother’s surname (or vice versa) for reasons not covered by administrative laws;
When an adult wants to change surname for valid reasons (e.g., surname is ridiculous, confusing, associated with crimes, or there is a compelling personal or family reason);
When civil registry officials decline to process the change administratively because it is substantial, disputed, or not squarely within R.A. 9255 or R.A. 9048.

9.2 Basic Features of a Rule 103 Petition

Filed with the Regional Trial Court where the petitioner has resided for the period required by the Rule (traditionally three years).
Petition states:
- Current name;
- Desired new name;
- Grounds for the change; and
- Supporting facts and evidence.
The court issues an order for publication in a newspaper of general circulation, to notify the public.
A hearing is held, evidence is presented.
If the court finds proper and reasonable cause, it issues a decision granting the change.
The court’s decision is then forwarded to the civil registrar, and the change is annotated in the child’s civil registry records.

Changing a child’s surname in this way is always guided by the “best interests of the child” doctrine.

10. Can the Child Later Drop the Father’s Surname?

A typical practical question:

Once an illegitimate child uses the father’s surname under R.A. 9255, can the child revert to the mother’s surname?

Civil registry rules generally treat the administrative grant under R.A. 9255 as a one-way change. Reversion to the mother’s surname is usually not available administratively, because:

It is no longer simply a first-time application to use the father’s surname.
Reversion is treated as a change of name requiring judicial proceedings (Rule 103), where the child (especially if already of age) must show proper and reasonable cause.

Court decisions have held that changing surnames—especially when it affects third-party rights and public records—cannot be done lightly and must be justified.

11. Special Situations and Practical Issues

11.1 Father Is Overseas or Deceased

If the father is abroad:
- He may execute consular documents (e.g., acknowledgment of paternity, affidavit) recognized under Philippine rules.
If the father has died, the possibility of using the father’s surname depends on:
- Whether there is existing valid proof of acknowledgment executed while he was alive; or
- Whether a court case for recognition of filiation can be filed using available evidence.

Without valid acknowledgment, the LCRO cannot simply presume paternity.

11.2 Father Is Married to Someone Else

The father’s existing marriage to another person does not prevent:

The establishment of filiation with an illegitimate child; or
The child’s right to support and successional rights appropriate to an illegitimate child; or
The child’s use of the father’s surname (if the law’s requirements are met).

However, this situation often leads to family conflict and sometimes disputes, which may push the issue into court rather than a straightforward administrative process.

11.3 Effect on Passports, School Records, IDs

Once the civil registry record is annotated to allow use of the father’s surname:

The child (or parent on the child’s behalf) can:
- Apply for corrected/updated PSA birth certificates;
- Request changes in school records;
- Apply for a passport using the new surname;
- Update other IDs (PhilHealth, SSS, GSIS, etc., as applicable) following the agencies’ internal rules.

Most agencies will require:

The annotated PSA birth certificate; and
Supporting IDs and affidavits, depending on their own regulations.

12. Adoption by the Biological or Step-Father

If the biological father adopts his own child, or a stepfather adopts the child:

Adoption creates a new legal relationship where the adoptee generally:
- Bears the surname of the adopter; and
- Acquires the rights of a legitimate child with respect to the adopter.

In this context:

The change of surname follows adoption law and its procedures (judicial or administrative, depending on the regime in force at the time), rather than R.A. 9255.

13. Guiding Principle: Best Interests of the Child

Across all these rules, the courts and civil registry officials are guided by the principle that:

In all questions relating to the care, custody, and change of name of a child, the best interests of the child shall be the paramount consideration.

So even when the law technically allows a change, courts will look at:

Potential confusion or harm to the child;
The nature of the relationship with the father and the mother;
The stability of the child’s identity and social environment;
The risk of abuse of the change to evade obligations or legal responsibilities.

14. Summary: Key Takeaways

Check the child’s status first. Is the child legitimate, illegitimate, or legitimated? This determines which rules apply.
Legitimate children use the father’s surname by default; corrections in records may require judicial proceedings if the error affects civil status or filiation.
Illegitimate children use the mother’s surname by default but may use the father’s surname under R.A. 9255 if:
- Filiation is expressly acknowledged in the manner required by law; and
- The proper administrative procedure (AUSF, filings at LCRO, etc.) is followed.
Using the father’s surname does not make the child legitimate. Status (legitimate vs illegitimate) is a different question, handled by legitimation, adoption, or judicial declaration.
If there is no acknowledgment or there is a paternity dispute, the issue must be taken to court—often through cases for recognition of filiation, change of name (Rule 103), and/or correction of entries (Rule 108).
Legitimation (R.A. 9858) and adoption can also lead to a change of surname to the father’s, but these follow their own sets of rules.
Once an illegitimate child uses the father’s surname under R.A. 9255, reverting to the mother’s surname generally requires a judicial change of name, invoking the best interests of the child.

15. Final Note

This is a general legal overview under Philippine law. Specific cases can be very fact-sensitive—dates of birth, marital status of the parents, existing documents, and family circumstances all matter.

For anyone seriously planning to change a child’s surname to the biological father’s—especially where there is conflict or unusual facts—it is prudent to:

Consult the Local Civil Registry Office for current administrative requirements; and
Seek advice from a Philippine family law practitioner to choose the correct legal route (administrative vs judicial, R.A. 9255 vs Rule 103/108, legitimation, adoption, etc.).