I. The practical problem this topic is really about

In the Philippines, a child’s surname on the birth certificate is not just a “name choice.” It is a legal marker tied to filiation (the legal relationship between parent and child). Because the surname is anchored to filiation, removing the father’s surname is rarely a simple affidavit exercise. It usually implicates one (or more) of these issues:

Was the child born legitimate, legitimated, or illegitimate?
Is the man whose surname appears on the record truly the child’s legal father?
Was paternity acknowledged correctly—or was there fraud, mistake, or lack of authority?
Is the desired change a “clerical error correction,” a “substantial change,” or a “status correction”?

An “Affidavit to Remove Father’s Surname” may exist as a document, but it typically cannot by itself override the underlying legal basis of the entry. The correct remedy depends on why the father’s surname is there and what you are trying to achieve.

II. Key legal building blocks (why an affidavit often isn’t enough)

A. Filiation drives the surname

Philippine law treats the surname as a consequence of filiation:

Legitimate children generally bear the father’s surname.
Illegitimate children generally bear the mother’s surname, but may use the father’s surname if paternity is recognized and legal requirements are met.
Legitimated children (originally illegitimate, later legitimated by subsequent valid marriage of parents) are treated as legitimate, including surname consequences.

So, to “remove” a father’s surname, you are typically:

undoing or disputing recognition of paternity, or
undoing or disputing legitimacy/legitimation status, or
correcting a record that should never have carried that surname.

B. Administrative correction vs judicial correction

Philippine civil registry rules distinguish:

Clerical/typographical errors (often correctable administratively), versus
Substantial changes affecting civil status, filiation, legitimacy, or paternity (generally judicial).

Changing a surname that is tied to paternity is commonly treated as substantial.

III. Typical scenarios and the correct “lane” to use

Scenario 1: Child is legitimate (parents married at birth) — you want to remove father’s surname

General rule: This is extremely difficult without attacking the child’s legitimate filiation. If the parents were married and the child was conceived or born during the marriage, the child is presumed legitimate.

What it usually requires:

Judicial action that changes/negates the legal link to the father (e.g., a successful paternity challenge in the proper case), not a simple affidavit.

Why affidavits fail here: A father’s “waiver” or mother’s affidavit cannot simply strip legitimacy-based filiation recognized by law and reflected in civil registry entries.

Scenario 2: Child is illegitimate, but birth certificate shows father’s surname because of recognition — you want to revert to mother’s surname

This is one of the most common real-world situations. There are sub-variations:

2A. Father recognized paternity properly, and child used father’s surname

If paternity recognition was valid, removing the father’s surname is normally not a mere clerical fix because it alters a consequence of recognized filiation.

Possible routes:

If the goal is only the surname (not disowning paternity), the legal room is narrow; the system generally treats the surname as linked to established filiation. This often becomes a judicial petition (and may still be denied if it appears to sever the legal incident of paternity without basis).
If the goal is to undo recognition because it was defective, forced, fraudulent, or unauthorized, then the core is an attack on recognition/paternity, which is generally judicial.

2B. Father’s name/surname appears due to mistake, fraud, simulation, or unauthorized signing

Examples:

Someone signed the acknowledgment without authority.
The mother was induced to sign false documents.
An “acknowledgment” was fabricated.
The father’s details were inserted despite lack of proper recognition.

Typical remedy: A judicial petition to correct/cancel entries affecting filiation, or to impugn/annul a defective recognition. Administrative correction is unlikely if the correction changes paternity-related entries.

Role of an affidavit: Affidavits can support the case (evidence of fraud/mistake), but usually do not substitute for the required judicial process.

Scenario 3: Legitimation — parents married after birth, and the child’s status or surname changed

Legitimation happens when:

A child is conceived and born outside a valid marriage, and
The parents later contract a valid marriage, and
At the time of conception, there was no legal impediment for them to marry each other (this is crucial).

Once legitimated, the child is treated as legitimate, often leading to using the father’s surname and legitimacy annotations in the record.

To remove father’s surname after legitimation: You would usually have to attack the fact or validity of legitimation (e.g., showing there was an impediment at conception, or the marriage was void, or legitimation requirements not met), which is substantial and typically judicial.

Affidavits alone are generally insufficient because legitimation is a status consequence of law.

Scenario 4: Child used father’s surname under the “illegitimate child uses father’s surname” mechanism, and now wants to change

Philippine rules allow an illegitimate child to use the father’s surname upon compliance with recognition requirements (commonly handled via civil registry processes depending on the factual posture). But once the record reflects recognition and the surname follows it, later removal tends to be treated as substantial.

Practical reality: If the child’s use of the father’s surname is anchored to recognized paternity, the state generally views a later “removal” as requiring a legal ground beyond preference—often requiring judicial intervention.

Scenario 5: The “father” on the record is not the biological father — removing surname is part of correcting paternity

This is the scenario that most directly aligns with “impugning paternity.”

Key distinction: Biology alone is not always decisive if legal presumptions apply (especially in marriage situations). The remedies differ depending on legitimacy and presumptions.

Likely remedy: A court action targeting filiation/paternity entries, supported by evidence (including, when allowed/ordered, DNA testing). This is not an affidavit-only route.

IV. “Impugning paternity” in Philippine practice (what it means and why it matters)

A. When paternity can be challenged

“Impugning” typically means disputing the legal father-child relationship. Philippine law has strong presumptions protecting legitimacy within marriage, and also recognizes voluntary acknowledgment for illegitimate children.

In broad terms:

If the child is presumed legitimate because of marriage, paternity challenges face strict rules, time considerations, and standing limitations.
If paternity is based on acknowledgment/recognition for an illegitimate child, challenges often revolve around validity of recognition and proof.

B. Standing (who can file) matters

Often, only specific persons can bring certain actions (e.g., the presumed father in legitimacy cases, or the child in some filiation disputes), and the proper remedy depends on who is initiating.

C. Surname change is a consequence, not the core claim

Courts typically treat “remove the father’s surname” as a request that flows from a deeper relief:

declaring that the man is not the father (or recognition is void), or
correcting the civil registry to reflect correct filiation.

V. Record correction options (administrative vs judicial) — how to choose

A. Administrative remedies (civil registrar / PSA processes)

Administrative processes are usually for:

typographical errors (misspellings, wrong letter/number),
obvious clerical mistakes,
some changes that do not touch civil status or filiation.

Surname removal tied to father’s identity/paternity is usually not purely clerical. If the correction would:

remove the father’s surname because the father entry itself is disputed,
change legitimacy/illegitimacy annotations,
delete the father’s name,
change filiation indicators,

…it is typically treated as substantial and routed to court.

B. Judicial remedies (RTC petitions and related actions)

Judicial action is usually needed when:

the correction affects filiation, legitimacy, paternity, legitimation, or civil status,
you seek cancellation or nullification of paternity-related entries,
there is contest, opposition, or a need for evidentiary hearing.

In practice, courts want:

clear factual basis,
proper parties notified,
publication/notice requirements complied with when applicable,
proof that the change is not being used to evade obligations or commit fraud.

VI. The “Affidavit to Remove Father’s Surname”: what it can and cannot do

A. What it can do

An affidavit can:

state facts under oath (e.g., how the entry happened, whether consent was given, circumstances of recognition),
support a civil registrar application if the matter is within administrative scope,
support a court case as evidence,
document the mother’s/affiant’s position for later proceedings.

B. What it generally cannot do by itself

An affidavit generally cannot:

nullify legitimate filiation created by marriage presumptions,
revoke a valid acknowledgment in a way that binds the state and changes the PSA record,
unilaterally alter paternity-based registry entries without the appropriate administrative/judicial authority,
“waive” a child’s legal status or rewrite filiation consequences solely by agreement of adults.

C. Common affidavit pitfalls

“Father agrees to remove surname.” Consent is not always legally sufficient if filiation is established.
Using the affidavit as a substitute for due process. The PSA/civil registrar will often require a court order when entries involve filiation.
Mismatch between goal and remedy. If the real objective is to correct paternity, the remedy must address paternity, not just the surname.

VII. Evidence considerations (what usually matters)

A. Civil registry documents

Certificate of Live Birth entries (father’s name, signatures, acknowledgment forms)
Marriage certificates (timing matters for legitimacy/legitimation)
Prior annotations, legitimation records

B. Proof of mistake or fraud

handwriting/signature issues,
witnesses to execution,
communications showing deceit,
proof of absence (e.g., alleged father abroad/never signed)

C. DNA testing

DNA evidence can be powerful, but admissibility and effect depend on the case type and the governing presumptions. In legitimacy contexts, courts may still require the proper action and standing; DNA does not automatically rewrite the record absent the correct legal pathway.

VIII. Child’s age and consent: minors vs adults

A. If the child is a minor

Actions are typically pursued by the parent/guardian, but courts will still focus on:

the child’s best interests,
stability of status,
whether the change improperly strips rights (support, inheritance).

B. If the child is of age

An adult child may have standing in certain filiation or name-related proceedings, and courts may weigh personal circumstances differently. But paternity-linked record changes remain substantial.

IX. Consequences of removing the father’s surname (often overlooked)

Removing the father’s surname can affect:

support claims (though support depends on filiation),
inheritance rights from the father and paternal relatives,
legitimacy/illegitimacy classification and related rights,
citizenship/derivative rights in rare cross-border contexts,
the child’s identity continuity in records (school, passports, benefits).

Courts and registrars are alert to attempts to:

evade support obligations,
mask trafficking/adoption irregularities,
alter identity for improper purposes.

X. How these issues map to the correct remedy (decision guide)

1) Is the child legitimate (parents married at birth or presumed legitimate)?

If yes, removing father’s surname generally requires judicial action attacking the legal basis of paternity/legitimacy.

2) Is the child illegitimate but using father’s surname because of recognition?

If recognition is valid and you just “want to remove,” it is often judicial and may be difficult without a legal ground.
If recognition is defective/fraudulent/unauthorized, the core is judicial correction/cancellation of paternity-related entries.

3) Was there legitimation by subsequent marriage?

If yes, undoing the surname typically requires undoing/invalidating the basis for legitimation—generally judicial.

4) Is it just a spelling/typographical error in the surname?

If genuinely typographical and not changing filiation, it may be administrative.

XI. Drafting realities: what an affidavit on this topic typically contains (and why)

When used as supporting evidence, affidavits commonly include:

the child’s identifying details and birth record identifiers,
the exact entry sought to be corrected,
the factual narrative explaining why the father’s surname/identity was entered,
whether any acknowledgment documents were signed, and by whom,
whether there was marriage, subsequent marriage, or impediments at conception (legitimation relevance),
the specific relief sought (reversion to mother’s surname; deletion/correction of father entry),
attachments (birth certificate copies, IDs, marriage records, proof of circumstances),
jurat (notarial oath), competent affiant, and, if needed, witness affidavits.

But the affidavit is typically an exhibit, not the operative authority to change PSA records in paternity-linked cases.

XII. Common misconceptions (and the correct framing)

“A notarized affidavit is enough to change PSA entries.” Usually false when filiation/paternity is implicated.
“If the father isn’t around, we can just remove his surname.” Absence is not automatically a legal ground to erase filiation consequences.
“If the father signs a waiver, the surname can be removed.” A parent’s waiver does not necessarily defeat the child’s legal filiation or the state’s interest in accurate civil status records.
“Changing surname is separate from paternity.” Often false in Philippine civil registry practice; surname is treated as a filiation incident.

XIII. Practical endpoint: what usually succeeds

In real Philippine practice, successful “removal of father’s surname” cases usually fall into one of these successful frames:

Clerical: The surname was misspelled or incorrectly typed, without touching paternity.
Wrong father entry: There is a provable mistake/fraud/unauthorized acknowledgment, and the court orders correction/cancellation/annotation.
Status correction: The entry reflects legitimacy/legitimation incorrectly, and a court corrects the underlying status; the surname follows.
Proper legal action on filiation: The legal father-child relationship is judicially determined to be different from what the registry shows.

XIV. The core takeaway

An “Affidavit to Remove Father’s Surname From a Child” is usually not the remedy; it is a piece of evidence. The decisive question is whether the father’s surname on the record is anchored to valid filiation (legitimacy, legitimation, or valid recognition). If yes, changing the surname generally requires a remedy that addresses that legal anchor—most often through judicial proceedings, not a unilateral affidavit. If the issue is truly clerical and does not disturb paternity or status, administrative correction may be possible.