I. Introduction
In Philippine law, the surname of a child born to a married woman is not determined simply by biological paternity. The controlling legal framework is based on filiation, legitimacy, and the strong statutory presumption that a child conceived or born during a valid marriage is the child of the spouses.
Thus, where a married woman gives birth to a child allegedly fathered by another man, the law does not automatically allow the child to use the biological father’s surname. Unless the child’s legal status is successfully changed through the proper judicial process, the child is generally treated as the legitimate child of the mother and her husband, and the child ordinarily bears the surname of the husband.
This rule may appear harsh in situations where everyone involved knows that the husband is not the biological father. However, Philippine law gives great weight to the stability of family relations, the legitimacy of children, and the conclusiveness of civil registry records unless altered by a competent court.
II. Governing Legal Concepts
A. Legitimacy
Under the Family Code of the Philippines, children conceived or born during the marriage of the parents are generally considered legitimate.
The key rule is that a child conceived or born during a valid marriage is presumed to be the child of the husband and wife. This presumption exists even if another man claims to be the biological father, and even if the mother asserts that the child was fathered by another man.
Legitimacy affects many legal consequences, including:
- the child’s surname;
- parental authority;
- support;
- successional rights;
- civil status;
- the contents of the birth certificate; and
- the legal identity of the child in the civil registry.
B. Filiation
Filiation is the legal relationship between a parent and a child. It may be:
- Legitimate filiation, where the child is legally considered born of the marriage; or
- Illegitimate filiation, where the child is born outside a valid marriage or is otherwise not legally considered legitimate.
A biological relationship alone does not always produce legal filiation. In the case of a child born to a married woman, the law first looks at the marriage and the presumption of legitimacy.
C. Surname as a Consequence of Filiation
A child’s surname follows the child’s legal filiation. Therefore, before asking what surname the child may use, one must first determine the child’s legal status.
In ordinary cases:
| Legal Status of Child | General Surname Rule |
|---|---|
| Legitimate child | Uses the surname of the father |
| Illegitimate child | Uses the surname of the mother, unless allowed by law to use the father’s surname |
| Child born to a married woman during marriage | Presumed legitimate child of the spouses, unless legitimacy is successfully impugned |
III. The Presumption of Legitimacy
A. Child Born During Marriage
The Family Code strongly presumes that a child conceived or born during the marriage is legitimate. This presumption applies even if the mother had sexual relations with another man.
The child is not considered illegitimate merely because:
- the mother says another man is the father;
- the biological father acknowledges the child;
- the husband is not listed as the father in the birth certificate;
- the parties are separated in fact;
- the spouses have not lived together for some time; or
- DNA testing suggests another man is the biological father.
The presumption of legitimacy remains until it is defeated in the manner required by law.
B. Purpose of the Presumption
The presumption protects:
- the child from the stigma and legal consequences of illegitimacy;
- the stability of marriage and family relations;
- the integrity of the civil registry;
- succession and support rights; and
- public policy favoring legitimacy.
The law prefers legitimacy over illegitimacy. Where the facts allow competing interpretations, Philippine law generally leans toward preserving the child’s legitimate status.
IV. Who May Challenge the Child’s Legitimacy?
A central point in this topic is that not everyone may challenge the legitimacy of a child.
Generally, the right to impugn legitimacy belongs to the husband, and in certain cases, his heirs. The mother, the alleged biological father, and the child generally cannot freely defeat the presumption of legitimacy merely by declaration.
This means that even if the mother and the biological father agree that the child is biologically theirs, they cannot simply bypass the husband’s legal status as presumed father.
A. The Husband
The husband is the principal person authorized to bring an action to impugn the child’s legitimacy.
He must do so within the period and on the grounds provided by law. If he does not timely challenge the child’s legitimacy, the child’s legitimate status may become legally fixed.
B. The Husband’s Heirs
The husband’s heirs may challenge legitimacy only in limited circumstances, such as when the husband died before the expiration of the period for bringing the action, or when other legally recognized grounds allow them to continue or initiate the action.
C. The Mother
The mother ordinarily cannot simply declare that her child is illegitimate when the law presumes the child to be legitimate.
Her admission of adultery or her statement that another man fathered the child is not, by itself, sufficient to destroy the child’s legitimate status.
D. The Alleged Biological Father
The alleged biological father cannot ordinarily force recognition of the child as his own when the child is legally presumed legitimate to the mother’s husband.
His acknowledgment, signature, affidavit, or private agreement with the mother does not automatically overcome the presumption of legitimacy.
E. The Child
The child’s own interest may be complex. While a child may later seek to establish or protect filiation in some contexts, the child cannot ordinarily be deprived of legitimate status casually or extrajudicially. The law treats legitimacy as a matter of public status, not a private label that parties may change at will.
V. Grounds for Impugning Legitimacy
The Family Code allows legitimacy to be challenged only on specific grounds. The law does not allow legitimacy to be attacked simply because someone claims another man is the biological father.
Common grounds include circumstances showing that it was physically impossible for the husband to have sexual intercourse with the wife within the relevant period of conception.
Examples may include:
- physical incapacity of the husband to have sexual intercourse;
- the husband and wife were living separately in such a way that sexual intercourse was physically impossible;
- serious illness or other conditions making intercourse impossible;
- scientific or biological evidence, in proper cases, showing impossibility of paternity; and
- other grounds recognized by the Family Code and jurisprudence.
The exact legal ground must fit the statute. The court does not simply ask, “Who is the biological father?” It asks whether the legal presumption of legitimacy has been overcome in the manner allowed by law.
VI. Period for Challenging Legitimacy
Actions to impugn legitimacy are subject to strict periods. These periods are important because once they lapse, the child’s status may no longer be questioned.
The period depends on circumstances such as where the husband or heirs reside and when they became aware of the child’s birth or its registration.
The policy behind these deadlines is to prevent a child’s civil status from being placed in uncertainty indefinitely.
Once the period to impugn legitimacy has expired, the child’s legitimate status generally becomes settled, even if later evidence suggests a different biological father.
VII. Effect on the Child’s Surname
A. General Rule: Child Uses the Husband’s Surname
If the child is born to a married woman during the marriage and legitimacy has not been successfully impugned, the child is treated as the legitimate child of the spouses.
As a legitimate child, the child generally uses the surname of the father — legally, the mother’s husband.
Therefore, even if another man is the biological father, the child’s surname is generally that of the husband unless a court declares otherwise.
B. The Biological Father’s Surname Cannot Be Used Merely by Agreement
The mother and the biological father cannot validly agree between themselves that the child will use the biological father’s surname if the child remains legally presumed legitimate to the husband.
A private agreement cannot override:
- the presumption of legitimacy;
- the child’s civil status;
- the law on surnames;
- the civil registry rules; or
- the rights of the husband and the child.
C. Birth Certificate Listing Another Man as Father
A birth certificate that names another man as father does not necessarily defeat the presumption of legitimacy.
Civil registry entries are important, but they cannot lawfully alter a child’s status in a way contrary to law. If the birth certificate incorrectly names the biological father while the mother was married to another man, correction may require a judicial proceeding, especially where the correction affects filiation, legitimacy, or surname.
D. Use of the Mother’s Surname
If the child is presumed legitimate, the child does not simply become entitled to use the mother’s surname as an illegitimate child.
The mother’s surname may be relevant if the child is legally declared illegitimate or if the child’s civil status is properly changed. But before that happens, the child’s legal status remains governed by the presumption of legitimacy.
E. Use of the Biological Father’s Surname Under R.A. No. 9255
Republic Act No. 9255 allows an illegitimate child to use the surname of the father if the father has expressly recognized the child through the record of birth, admission in a public document, or private handwritten instrument.
However, this law applies to illegitimate children.
A child born to a married woman is not automatically illegitimate. If the child is still legally presumed legitimate to the mother’s husband, R.A. No. 9255 does not simply authorize the biological father to give the child his surname.
The child must first be legally situated as an illegitimate child in relation to the biological father. That normally requires overcoming the presumption of legitimacy through the proper judicial process.
VIII. Civil Registry Issues
A. Administrative Correction vs. Judicial Correction
Philippine law allows certain clerical or typographical errors in the civil registry to be corrected administratively. However, changes involving civil status, legitimacy, filiation, nationality, or substantial surname issues generally require judicial proceedings.
Changing the surname of a child born to a married woman from the husband’s surname to another man’s surname is not a mere clerical correction. It affects filiation and civil status.
Therefore, it ordinarily cannot be done through a simple administrative correction.
B. Role of the Local Civil Registrar
The Local Civil Registrar records facts supplied in the certificate of live birth. However, the registrar does not have the power to adjudicate complex questions of paternity, legitimacy, or filiation.
If the facts show that the mother was married at the time of birth, the registrar may require compliance with laws and regulations recognizing the husband as the presumed father.
C. Philippine Statistics Authority Records
The PSA record reflects the civil registry entry. If the entry is wrong or legally inconsistent, the PSA will not usually change it merely because the mother, biological father, or child requests it.
A court order may be required where the requested change affects:
- the child’s legitimacy;
- the father’s identity;
- the child’s surname;
- parental filiation; or
- inheritance or support rights.
IX. Judicial Proceedings That May Be Involved
Depending on the facts, several proceedings may be relevant.
A. Action to Impugn Legitimacy
This is the primary action to defeat the presumption that the child is legitimate to the husband.
It is usually brought by the husband within the period allowed by law.
If successful, the child may no longer be considered the legitimate child of the husband.
B. Petition for Correction or Cancellation of Civil Registry Entry
If the birth certificate contains entries inconsistent with the child’s true legal status, a petition may be filed to correct or cancel entries.
Where the correction affects filiation, legitimacy, or surname, it is typically judicial in nature.
C. Action to Establish Illegitimate Filiation
After the presumption of legitimacy is overcome, the child or father may need to establish illegitimate filiation with the biological father.
This may involve:
- acknowledgment in the birth certificate;
- admission in a public document;
- private handwritten instrument signed by the father;
- open and continuous possession of the status of a child; or
- other evidence allowed by law.
D. Petition for Change of Name
A change of surname may also require a petition for change of name when the requested surname is not a simple clerical correction but a substantial legal change.
Courts generally require proper grounds, publication, notice to affected parties, and protection of the child’s best interests.
X. DNA Testing and Its Legal Effect
DNA evidence may be relevant in paternity disputes. Philippine courts have recognized DNA testing as a valuable scientific tool.
However, DNA evidence does not automatically change a child’s surname or civil status.
In this specific context, DNA evidence may support an action to impugn legitimacy or establish biological paternity, but it must be presented in the proper proceeding. A DNA result by itself does not authorize the Local Civil Registrar or PSA to change the child’s surname from the husband’s surname to that of another man.
The legal question is not only biological truth. It is also whether the presumption of legitimacy has been validly overcome under the Family Code.
XI. Effect of Legal Separation, Annulment, Declaration of Nullity, or De Facto Separation
A. De Facto Separation
If the spouses are merely separated in fact, the marriage still exists. A child born during the marriage remains presumed legitimate unless the presumption is successfully challenged.
Living apart does not automatically make the child illegitimate.
B. Legal Separation
Legal separation does not dissolve the marriage. Therefore, the presumption of legitimacy may still apply to a child conceived or born during the marriage, subject to the rules on impugning legitimacy.
C. Annulment or Declaration of Nullity
The effect depends on the timing of conception, birth, and the legal status of the marriage.
Even in cases involving void or voidable marriages, the Family Code contains rules on the status of children. Some children of void marriages may still be considered legitimate under specific provisions, such as children conceived or born before the judgment of annulment or absolute nullity under certain circumstances.
Therefore, one cannot assume that a child is illegitimate merely because the marriage was later annulled or declared void.
D. Subsequent Marriage to the Biological Father
If the married woman later marries the biological father, that later marriage does not automatically change the surname or status of the child if the child was previously presumed legitimate to the former husband.
Legitimation may be possible only under specific conditions, generally involving children who were conceived and born outside a valid marriage and whose parents were not disqualified from marrying each other at the time of conception. A child legally presumed legitimate to another man does not simply become legitimated by the mother’s later marriage to the biological father.
XII. Adultery, Concubinage, and Criminal Law Considerations
The issue of surname is civil in nature, but the facts may overlap with criminal law.
If a married woman has sexual relations with a man not her husband, issues of adultery may arise under the Revised Penal Code. However, a criminal case for adultery does not itself determine the child’s surname.
Even proof of adultery does not automatically make the child illegitimate. The child’s legitimacy must still be addressed under the Family Code.
The law separates:
- the criminal liability of adults, if any;
- the civil status of the child;
- the child’s surname;
- support obligations; and
- succession rights.
The child is not punished for the acts of the parents.
XIII. Support Obligations
A. If the Child Remains Legitimate to the Husband
If the child is legally considered legitimate, the husband may be treated as the legal father for purposes of support, parental authority, and related obligations, unless legitimacy is successfully impugned.
B. If Legitimacy Is Successfully Impugned
If the child is judicially determined not to be the legitimate child of the husband, support may then be pursued from the biological father, provided filiation is established.
C. Biological Father’s Voluntary Support
A biological father may voluntarily provide support. However, voluntary support does not necessarily confer surname rights or legal filiation if the child remains legally presumed legitimate to the husband.
XIV. Succession and Inheritance
The surname issue is closely tied to inheritance.
If the child remains legitimate to the husband, the child may have successional rights as a legitimate child of the husband.
If the child is later declared not legitimate to the husband and is instead established as the illegitimate child of the biological father, the child’s inheritance rights change accordingly.
Under Philippine succession law, legitimate and illegitimate children have different legitime shares. Therefore, courts are careful in proceedings that alter filiation or legitimacy because such changes affect not only names but also property rights.
XV. Parental Authority and Custody
The surname does not alone determine custody, but it reflects legal filiation.
If the child is legitimate, parental authority generally belongs to the father and mother jointly.
If the child is illegitimate, parental authority generally belongs to the mother, subject to rights of support, visitation, and other matters involving the father if filiation is established.
Thus, changing the child’s status from legitimate to illegitimate has consequences beyond the surname.
XVI. Common Scenarios
Scenario 1: Married Woman Gives Birth While Living With Her Husband
The child is presumed legitimate. The child generally uses the husband’s surname. Another man cannot simply sign the birth certificate and give the child his surname.
Scenario 2: Married Woman Gives Birth While Separated From Husband
The child is still presumed legitimate if born during the marriage. De facto separation alone does not automatically defeat legitimacy.
The husband may challenge legitimacy if legal grounds exist and the action is timely filed.
Scenario 3: Husband Knows He Is Not the Biological Father But Does Nothing
If the husband does not timely impugn legitimacy, the child’s legitimate status may become fixed. Later attempts by the mother, biological father, or other parties may fail.
Scenario 4: Biological Father Signs the Birth Certificate
His signature may be evidence of acknowledgment, but if the child is legally presumed legitimate to the husband, the signature does not automatically allow use of the biological father’s surname.
Scenario 5: DNA Test Shows Another Man Is the Father
The DNA result may be evidence, but a proper judicial proceeding is still required. The surname and civil registry entries do not automatically change.
Scenario 6: Birth Certificate Lists the Biological Father, Not the Husband
The entry may be legally problematic. Correction may require court action because the issue affects filiation and legitimacy.
Scenario 7: Mother Wants the Child to Use Her Maiden Surname
If the child is presumed legitimate, the mother cannot unilaterally make the child use her maiden surname as though the child were illegitimate.
Scenario 8: Husband Consents to the Child Using the Biological Father’s Surname
The husband’s consent may be relevant, but consent alone may not be sufficient. Since legitimacy and civil status are matters of law and public record, proper judicial proceedings may still be required.
Scenario 9: The Child Is Already an Adult and Wants to Use the Biological Father’s Surname
The adult child may need to pursue the appropriate judicial remedies. The passage of time may make an action to impugn legitimacy unavailable if the statutory period has expired. A change of name petition may also face difficulty if it contradicts settled filiation.
Scenario 10: The Mother Later Marries the Biological Father
The later marriage does not automatically change the child’s legal filiation or surname if the child was legally presumed legitimate to the former husband.
XVII. Administrative Use vs. Legal Surname
A child may sometimes be informally known in school, the community, or family circles by a surname different from the PSA record. However, informal usage does not necessarily change the child’s legal surname.
For official purposes, the child’s legal surname is the one reflected in the valid civil registry record, unless corrected or changed by competent authority.
Official documents affected include:
- school records;
- passport;
- national ID;
- baptismal records, though ecclesiastical records are not controlling civil records;
- medical records;
- bank records;
- government benefits;
- inheritance documents; and
- court records.
XVIII. Relevant Laws
A. Family Code of the Philippines
The Family Code governs legitimacy, filiation, parental authority, support, and related family-law consequences.
Key areas include:
- presumption of legitimacy;
- grounds for impugning legitimacy;
- periods for filing the action;
- proof of filiation;
- rights of legitimate and illegitimate children; and
- parental authority.
B. Civil Code of the Philippines
The Civil Code remains relevant for names, surnames, civil personality, succession, and certain family relations not superseded by the Family Code.
C. Republic Act No. 9255
R.A. No. 9255 amended Article 176 of the Family Code and allows illegitimate children to use the surname of their father if filiation has been expressly recognized in the manner provided by law.
However, it does not automatically apply to a child who is legally presumed legitimate to the mother’s husband.
D. Republic Act No. 9048, as amended by R.A. No. 10172
These laws allow administrative correction of certain clerical or typographical errors and certain changes involving first name, sex, date of birth, or day/month of birth under specified conditions.
They do not generally allow administrative changes that involve substantial questions of legitimacy, filiation, or paternity.
E. Rules of Court
Judicial petitions involving correction of entries, cancellation of entries, change of name, or status issues may be governed by the Rules of Court, including rules on adversarial proceedings, notice, publication, and participation of affected parties.
XIX. Jurisprudential Principles
Philippine jurisprudence has consistently treated legitimacy as a protected status. Courts generally observe these principles:
- The law favors legitimacy.
- A child born or conceived during marriage is presumed legitimate.
- The presumption of legitimacy cannot be overthrown by mere declarations of the mother.
- The alleged biological father cannot casually defeat the husband’s legal paternity.
- Civil registry entries affecting filiation cannot be substantially changed without proper proceedings.
- DNA evidence may be relevant but must be used in the proper legal action.
- The best interests of the child matter, but they operate within the framework of law.
- The child’s status cannot be left to private arrangements among adults.
A commonly cited principle is that the legitimacy of a child is not subject to collateral attack. It must be challenged directly in the action and manner provided by law.
XX. Practical Effects on the Birth Certificate
A. Father’s Name
Where the mother is married, the husband is generally the presumed father. Listing another man as father may create a conflict between the birth record and the law.
B. Child’s Surname
If the child is presumed legitimate, the child generally carries the husband’s surname.
C. Middle Name
In Philippine naming convention, a legitimate child typically carries the mother’s maiden surname as middle name and the father’s surname as surname.
If the child is illegitimate, the child usually carries the mother’s surname, though under R.A. No. 9255 the child may use the father’s surname upon proper acknowledgment.
D. Correction of Entries
If the child’s birth certificate names the wrong legal father or uses a questionable surname, the proper remedy depends on whether the issue is clerical or substantial.
A wrong spelling may be administrative. A wrong father, wrong surname, or wrong legitimacy status is usually substantial.
XXI. The Child’s Best Interest
The best interest of the child is a central policy consideration, but it does not mean adults can freely choose whichever surname is emotionally or socially convenient.
The child’s best interest includes:
- legal stability;
- truthful identity;
- protection from illegitimacy where the law presumes legitimacy;
- entitlement to support;
- succession rights;
- avoidance of fraudulent or inconsistent records; and
- preservation of lawful family relations.
Courts may consider the child’s welfare, but they must also follow statutory rules on legitimacy, filiation, and names.
XXII. Comparison: Biological Paternity vs. Legal Paternity
| Issue | Biological Father | Legal Father |
|---|---|---|
| Based on | Genetic relationship | Law, marriage, filiation, court records |
| Can determine surname automatically? | No, not when child is presumed legitimate to another man | Generally yes, if legal filiation exists |
| Can sign birth certificate? | May attempt, but effect is limited if mother is married | Husband is presumed father |
| Can owe support? | Yes, if filiation is legally established | Yes, if child is legally his |
| Can transmit surname? | Only if law allows and filiation/status supports it | Yes, for legitimate child |
| Can be recognized by private agreement? | Not enough where legitimacy is presumed in favor of husband | Legal status controls |
XXIII. Why the Biological Father’s Surname Is Not Automatically Allowed
The core reason is that Philippine law does not treat the issue as a mere naming preference.
Allowing the biological father’s surname without first resolving legitimacy would effectively declare that:
- the child is not the husband’s child;
- the child is illegitimate as to the mother and biological father;
- the husband has no paternal status;
- the biological father has legal filiation;
- succession rights are changed; and
- parental authority and support obligations are altered.
These are judicial questions, not administrative choices.
XXIV. Legal Remedies in Proper Sequence
The usual legal sequence is:
- determine whether the child is presumed legitimate;
- if yes, determine whether the proper party can still impugn legitimacy;
- file the appropriate action to impugn legitimacy if legally available;
- present evidence, possibly including DNA evidence;
- obtain a court ruling;
- if legitimacy is defeated, establish filiation with the biological father;
- apply the correct surname rules;
- correct the civil registry entries if ordered by the court.
Skipping these steps may result in an invalid or challengeable civil registry entry.
XXV. Limits of Private Documents
The following documents may be relevant evidence but are not automatically conclusive:
- affidavit of acknowledgment by the biological father;
- affidavit of the mother;
- agreement among the mother, husband, and biological father;
- barangay certification;
- baptismal certificate;
- school records;
- hospital records;
- DNA test results;
- notarized admission of paternity; and
- private family settlement.
They may support a case, but they do not by themselves change civil status where the law requires judicial determination.
XXVI. Consequences of Incorrect Registration
Incorrectly registering the child under the biological father’s surname while the mother is married may create future problems, including:
- PSA inconsistencies;
- passport delays;
- school record conflicts;
- inheritance disputes;
- support disputes;
- questions in marriage records later in life;
- problems with government benefits;
- difficulty correcting records after many years; and
- possible allegations of false entries.
Because the birth certificate is a public document, accuracy matters. The person supplying information for registration should not treat the surname as a matter of private convenience.
XXVII. Role of the Husband’s Consent
Even if the husband agrees that the child is not his, the law may still require judicial action. His consent does not automatically alter the child’s civil status.
However, his participation may matter in a proper case. If he is the authorized party to impugn legitimacy and he acts within the legal period, his action may be decisive.
If he fails to act within the period, later consent may not revive a lost remedy.
XXVIII. Role of the Mother’s Admission
The mother’s admission that another man fathered the child is not enough by itself. The law is cautious because allowing a mother’s statement alone to bastardize a child would expose children to instability, coercion, fraud, and shifting family conflicts.
The mother’s statement may be evidence, but legitimacy must be challenged according to law.
XXIX. Role of the Biological Father’s Recognition
Recognition by the biological father is important only when the child is legally capable of being recognized as his illegitimate child.
If the child remains presumed legitimate to the mother’s husband, the biological father’s recognition does not automatically control.
Recognition cannot be used as a shortcut to defeat the presumption of legitimacy.
XXX. When the Child May Use the Biological Father’s Surname
The child may use the biological father’s surname only if the law recognizes the child’s filiation to that biological father in a manner that permits such use.
This usually requires that:
- the presumption of legitimacy in favor of the husband has been overcome, if applicable;
- the biological father has legally recognized the child;
- the child is legally considered illegitimate in relation to the biological father, unless another legal status applies;
- the requirements of R.A. No. 9255 and civil registry rules are met; and
- any necessary court or administrative process has been completed.
XXXI. When the Child May Use the Mother’s Surname
The child may use the mother’s surname if the child is legally considered illegitimate and no valid use of the father’s surname is made under R.A. No. 9255.
But where the mother was married at the time of birth and the child is presumed legitimate, the mother’s surname cannot simply be chosen as though the child were born outside marriage.
XXXII. When the Child Must Use the Husband’s Surname
The child generally uses the husband’s surname when:
- the mother was married at conception or birth;
- the child is presumed legitimate;
- no successful action has impugned legitimacy;
- the husband remains the legal father; and
- the civil registry records reflect or should reflect legitimate filiation.
XXXIII. Important Distinction: “Real Father” vs. “Father in Law”
In ordinary speech, people may refer to the biological father as the “real father.” In law, however, the controlling question is often who the legal father is.
The legal father is the person whom the law recognizes as father for purposes of surname, support, parental authority, inheritance, and civil status.
In the case of a child born to a married woman, the husband may be the legal father even if he is not the biological father, unless the presumption of legitimacy is successfully overcome.
XXXIV. Public Policy
The law’s strictness is based on public policy. It aims to avoid situations where a child’s identity changes depending on adult conflict or convenience.
The policy includes:
- protecting children from illegitimacy;
- preserving family stability;
- avoiding fraudulent birth registrations;
- preventing endless paternity disputes;
- protecting inheritance rights;
- ensuring orderly civil records; and
- respecting marriage as a legal institution.
XXXV. Summary of the Rule
A child born to a married woman by another man is, in Philippine law, generally presumed to be the legitimate child of the married woman and her husband.
Because of that presumption:
- the child generally uses the husband’s surname;
- the biological father’s surname cannot be used merely by acknowledgment or agreement;
- the mother cannot unilaterally declare the child illegitimate;
- DNA evidence does not automatically change the child’s civil status;
- civil registry correction usually requires judicial action if filiation or legitimacy is affected;
- R.A. No. 9255 applies only after the child is legally treated as an illegitimate child of the biological father; and
- the presumption of legitimacy must be challenged by the proper party, on proper grounds, within the proper period.
The central legal principle is that surname follows legal filiation, not merely biological paternity.