Family tree / genealogy chart illustrating generational and collateral relationships relevant to which relatives are barred from marrying under Philippine law

Void Marriages Between Relatives in the Philippines Under Articles 37 and 38

Not every void marriage in the Philippines involves bigamy or an underage spouse. The Family Code also voids a marriage outright — from the moment it was celebrated, with no need for either party to have known better — simply because of who the two parties are to each other. Two separate provisions do this work: Article 37 voids marriages between close blood relatives as incestuous, and Article 38 voids nine further categories of marriages, mostly between relatives by adoption or by marriage (affinity), as contrary to public policy. This guide explains exactly which relationships fall into each category, why the law treats them differently from an annulment ground, and what that void status actually means for children, property, and remarriage.

Direct Answer

Under Article 37 of the Family Code, a marriage between ascendants and descendants of any degree, or between brothers and sisters of full or half blood, is incestuous and void from the beginning, regardless of whether the relationship is legitimate or illegitimate. Under Article 38, nine further categories of marriage are void for reasons of public policy: marriages between collateral blood relatives up to the fourth civil degree, between step-parents and step-children, between parents-in-law and children-in-law, between an adopting parent and the adopted child, between the surviving spouse of the adopter and the adopted child, between the surviving spouse of the adopted child and the adopter, between an adopted child and a legitimate child of the adopter, between adopted children of the same adopter, and between two people where one killed the other’s spouse (or their own spouse) intending to marry the other. None of these marriages need a court to make them void — the law itself withholds legal effect from the moment of celebration. A court judgment is still required, however, before either party can be treated as free to remarry, and the consequences for children and property differ sharply from those of a marriage annulled under Article 45. This guide does not address bigamous marriages under Article 35(4), which are void for an entirely different reason (an existing prior marriage) and are covered in FamilyCode.ph’s separate guide on bigamy and void marriages.

Decision Snapshot

  • Applies to: Anyone assessing whether a marriage between relatives — by blood, by adoption, or by marriage (in-laws and step-relations) — is legally valid in the Philippines.
  • Core legal status: These marriages are void from the beginning under Articles 37 and 38 of the Family Code — they are not annulled, because they never had legal effect to begin with.
  • Two different articles, two different lists: Article 37 covers only direct-line relatives (ascendants/descendants) and full or half siblings; Article 38 covers nine additional, more distant relationships tied to public policy rather than blood alone.
  • Consequence for children: Unlike a marriage voided under Article 36, children of a marriage void under Articles 37 or 38 are not given legitimate status by Article 54 — they are illegitimate, subject to the ordinary rules on filiation and support.
  • Still need a court judgment: Even though these marriages are void by operation of law, Article 40 still requires a final court judgment declaring the marriage void before either party may validly remarry.

Key Takeaways

  • Article 37 voids only two categories: relatives in the direct line (ascendants and descendants, of any degree) and siblings, whether full-blood or half-blood, and it applies whether the parties are legitimate or illegitimate.
  • Article 38 lists nine further categories void for public policy: collateral blood relatives to the fourth civil degree, step-parent/step-child, parent-in-law/child-in-law, and five distinct adoption-related pairings, plus marriages motivated by killing a spouse.
  • Both articles void the marriage “from the beginning” — there is no waiting period, no cohabitation-based cure, and no way for the parties’ later conduct to validate the marriage, unlike several Article 45 annulment grounds.
  • A void marriage under either article still requires a Family Court judgment of absolute nullity before either party can be treated as legally free to marry someone else, per Article 40.
  • The action or defense to have such a marriage declared void does not prescribe — it can be raised at any time, per Article 39 as amended by Republic Act No. 8533.
  • Article 54 gives legitimate status only to children conceived or born before a final Article 36 (or Article 53) judgment — it does not extend that protection to children of marriages void under Articles 37 or 38, who are illegitimate.
  • Property acquired by the couple is not governed by the absolute community or conjugal partnership rules that apply to a valid marriage; it generally falls under the co-ownership rules of Articles 147 or 148, depending on each party’s capacity to marry.

In This Guide

Authority What it governs Relevance
Family Code of the Philippines (Executive Order No. 209), Art. 37 Declares marriages between ascendants/descendants of any degree, and between siblings of full or half blood, incestuous and void from the beginning The core rule for the direct-line and sibling category of void marriages
Family Code, Art. 38 Lists nine further categories of marriage void for reasons of public policy, covering collateral relatives, step-relations, in-laws, and several adoption-based relationships, plus killing-a-spouse cases The core rule for the broader public-policy category
Family Code, Art. 35 Separate catalog of void marriages (underage parties, lack of authority to solemnize, no license, bigamy, mistaken identity, and certain subsequent marriages) Shows how Articles 37 and 38 fit within the Family Code’s overall scheme of void marriages
Family Code, Art. 39, as amended by Republic Act No. 8533 (1998) States that the action or defense for declaration of absolute nullity of a marriage does not prescribe Confirms there is no filing deadline for challenging a marriage under Article 37 or 38
Family Code, Art. 40 Requires a final judgment declaring a marriage void before that nullity may be invoked for remarriage Explains why a court case is still necessary even though the marriage is void by operation of law
Family Code, Art. 54 Gives legitimate status only to children conceived or born before finality of a judgment under Article 36, or of a subsequent marriage under Article 53 Establishes that children of an Article 37 or 38 marriage do not receive this protection and are illegitimate
Family Code, Arts. 147–148 Co-ownership rules for property acquired by a man and a woman who live together without a valid marriage Governs property division for couples whose marriage is void under Article 37 or 38
A.M. No. 02-11-10-SC, Rule on Declaration of Absolute Nullity of Void Marriages and Annulment of Voidable Marriages (2003), Sec. 2(a) Provides that a petition for declaration of absolute nullity of a void marriage may be filed solely by the husband or the wife Governs who has standing to bring the case and how the petition is filed

Who This Applies To

This guide applies to anyone assessing whether a marriage they entered into, or are considering, falls within a relationship the Family Code treats as an absolute bar to marriage — whether that relationship is by blood (consanguinity), by a prior marriage in the family (affinity), or by adoption. It applies regardless of whether both parties knew about the relationship at the time, since Articles 37 and 38 do not require intent, deception, or bad faith — the relationship itself is enough. It does not apply to a marriage that is bigamous because one spouse was already validly married to someone else, which is void under a different provision (Article 35(4)) and is covered in FamilyCode.ph’s guide to bigamy and void marriages. It also does not apply to a marriage that is merely voidable for one of the six grounds under Article 45, such as fraud or a concealed condition, which remains valid unless and until a court annuls it — see FamilyCode.ph’s guide to grounds for annulment under Article 45 for that separate framework.

Article 37: Incestuous Marriages

Article 37 is short and categorical. It voids, as incestuous, marriages between two groups of relatives:

Category What it covers
1. Ascendants and descendants Any degree in the direct line — for example, parent and child, grandparent and grandchild, and further up or down the same line
2. Brothers and sisters Whether of the full blood (sharing both parents) or the half blood (sharing only one parent)

The statute applies “whether the relationship between the parties be legitimate or illegitimate” — meaning it makes no difference whether the family relationship itself arose from a valid marriage, a void marriage, or no marriage at all. A parent and child, or two siblings, cannot validly marry each other in the Philippines under any circumstance that Article 37 recognizes. There is no civil-degree limit on the ascendant-descendant line the way there is for collateral relatives under Article 38 — it applies at any degree, however distant the direct line runs.

Article 38: Marriages Void for Public Policy

Article 38 voids nine further, more specific categories of marriage. Unlike Article 37, several of these relationships are not blood relationships at all — they arise from a prior marriage in the family (affinity) or from adoption, and the law bars them as a matter of public policy rather than biology.

# Relationship voided Type of relationship
1 Collateral blood relatives, up to the fourth civil degree (for example, first cousins) Consanguinity (blood), collateral line
2 Step-parents and step-children Affinity, created by a parent’s remarriage
3 Parents-in-law and children-in-law Affinity, created by marriage
4 The adopting parent and the adopted child Adoptive relationship
5 The surviving spouse of the adopting parent and the adopted child Adoptive relationship, affinity
6 The surviving spouse of the adopted child and the adopter Adoptive relationship, affinity
7 An adopted child and a legitimate child of the adopter Adoptive relationship
8 Two adopted children of the same adopter Adoptive relationship
9 Two parties where one, intending to marry the other, killed that other person’s spouse, or killed his or her own spouse Public-policy bar unrelated to family relationship

A few distinctions are worth flagging. First, item 1 is narrower than Article 37’s ascendant-descendant rule: it stops at the fourth civil degree of the collateral line, so a marriage between more distant collateral relatives outside that degree is not barred by Article 38 on this basis (though it could still raise other legal issues depending on the facts). Second, items 2 through 8 show that the adoptive relationships Article 38 protects are extensive — they reach not only the adopter and the adopted child directly, but also the adopted child’s relationship to the adopter’s other children, to other children the same adopter has adopted, and to the surviving spouses on both sides of the adoption. Third, item 9 is not a family-relationship bar at all; it is a public-policy rule aimed at preventing someone from profiting, through marriage, from having killed a rival or their own spouse.

Evidence and Documents That May Matter

Because both articles turn on establishing a specific family or legal relationship, proof of that relationship is generally the central evidentiary question in a case under either provision. Depending on which relationship is alleged, records that may be relevant include:

  • PSA-issued birth certificates establishing parentage, sibling relationships, or the chain connecting ascendants and descendants.
  • Marriage certificates showing the prior marriage that created a step-relationship or in-law relationship.
  • Adoption decrees and the resulting amended birth certificate, which establish an adoptive parent-child relationship and, by extension, the further relationships Article 38 protects.
  • Death certificates, where relevant to identifying a “surviving spouse” under items 5 or 6 of Article 38.
  • Where item 9 of Article 38 is alleged, the final judgment of conviction or other court records establishing the killing and its connection to the marriage.

Civil-registry documents are generally the most reliable starting point, since Articles 37 and 38 turn on formally established relationships rather than on the parties’ subjective understanding of their own family tree. A lawyer or the Family Court can advise on what additional proof is needed once the specific relationship at issue is identified.

Process: What Generally Happens

A case to have a marriage declared void under Article 37 or 38 follows the same special procedure that governs every other petition for declaration of absolute nullity of marriage in the Philippines: A.M. No. 02-11-10-SC. That means the same venue rules, the same requirement that only the husband or the wife may file the petition, the same public-prosecutor collusion check where the respondent does not genuinely contest the case, the same mandatory pre-trial and judge-conducted trial, and the same finality, registration, and PSA-annotation steps before the change in status is complete on official record. FamilyCode.ph’s guide to the annulment and nullity process, step by step walks through each of those stages in full and applies equally here — this guide does not repeat that procedural detail, since the mechanics of filing, service, trial, and registration do not change based on which void-marriage ground is alleged.

What does change is the substance the petitioner must prove: instead of psychological incapacity or a prior undissolved marriage, the petition must establish the specific relationship — ascendant-descendant, sibling, collateral relative within the fourth degree, step-relation, in-law, or one of the adoption-based pairings — that brings the marriage within Article 37 or 38.

Legal Effects, Rights and Limits

A marriage void under Article 37 or 38 never created a valid husband-and-wife relationship, but several practical consequences still depend on a court’s formal declaration:

Remarriage. Article 40 requires a final judgment declaring the marriage void before either party may be treated as legally free to marry someone else — the same rule that applies to bigamous marriages and to nullity under Article 36. Acting on a private, undocumented belief that a marriage was void, without the required court judgment, risks exposing a party to the same problems as if they had simply remarried without ending a valid prior marriage.

Children. This is one of the sharpest differences between an Article 37 or 38 case and a case under Article 36. Article 54 expressly gives legitimate status to children conceived or born before a final judgment of nullity under Article 36 (and to children of certain subsequent marriages under Article 53) — but it does not extend that protection to children of a marriage void under Article 37 or 38. Those children are illegitimate. This affects surname use, parental authority arrangements, and the applicable support and inheritance rules, though it does not affect a child’s right to support or to be recognized by a parent who has been established as such.

Property. A valid marriage produces either an absolute community or a conjugal partnership of gains, depending on the couple’s regime. A marriage void under Article 37 or 38 produces neither. Property the couple acquired is instead generally governed by the co-ownership rules of Article 147 (where both parties were legally capacitated to marry each other apart from the prohibited relationship itself, and lived exclusively as husband and wife) or Article 148 (where one or both parties were not capacitated, or the relationship was otherwise defective in a way that removes it from Article 147). FamilyCode.ph’s guide to property rights under Articles 147 and 148 explains how courts apply this distinction in practice.

No prescriptive period. Under Article 39, as amended by Republic Act No. 8533, the action or defense to have the marriage declared void does not prescribe. A party, or an interested person with the required standing, is not barred by the mere passage of time from raising the marriage’s nullity.

Common Misunderstandings

  • “If we didn’t know we were related, the marriage should still count.” Articles 37 and 38 do not require knowledge or intent. The relationship itself makes the marriage void, regardless of whether either party was aware of it at the time.
  • “A step-relationship isn’t a real family relationship, so it shouldn’t matter.” Article 38 treats step-parent/step-child and parent-in-law/child-in-law relationships (relationships by affinity, created through marriage) the same as many blood relationships for this purpose — both are grounds that void the marriage.
  • “Since the marriage is void anyway, we don’t need to go to court.” The marriage has no legal effect from the start, but Article 40 still requires a final court judgment before either party can be treated as free to remarry, and civil-registry records will not reflect the void status without that judgment being registered.
  • “Our children would be illegitimate either way, so it doesn’t matter which void-marriage ground applies.” It does matter. Article 54 gives legitimate status to children of an Article 36 nullity case (and certain Article 53 remarriages) but not to children of an Article 37 or 38 case — the specific ground changes the children’s legal status.
  • “Cousins can never marry in the Philippines.” Article 38 bars collateral blood relatives only up to the fourth civil degree. Whether a specific cousin relationship falls within or outside that degree is a factual question that should be confirmed against the actual family relationship, not assumed.

Practical Checklist

  1. Identify precisely how the two parties are related — by blood, by a prior marriage in the family, or through adoption — before assuming which article, if any, applies.
  2. Gather PSA-issued civil-registry documents (birth certificates, marriage certificates, adoption decrees) that establish or disprove the relationship.
  3. If the relationship is a collateral blood relationship, confirm the exact civil degree rather than assuming it falls inside or outside the fourth-degree limit.
  4. Do not treat the marriage as informally “over” or irrelevant to remarriage plans without a final court judgment — Article 40 still requires one.
  5. If children are involved, discuss with counsel how illegitimate status under Article 54 affects surname, parental authority, and support arrangements in the specific case.
  6. Consult a lawyer or the Public Attorney’s Office, if you qualify, before filing or responding to a petition — standing to sue and the required proof depend on the specific relationship alleged.

Frequently Asked Questions

Can first cousins legally marry in the Philippines?

Article 38(1) voids marriages between collateral blood relatives up to the fourth civil degree, which includes first cousins. A marriage between first cousins is void for reasons of public policy under this provision.

Is a marriage between a step-parent and a step-child void even if there is no blood relationship?

Yes. Article 38(2) voids marriages between step-parents and step-children specifically because the relationship arises through a parent’s marriage (affinity), regardless of the absence of a blood tie.

Does it matter if both parties genuinely did not know they were related?

No. Articles 37 and 38 do not require knowledge, intent, or fault on either party’s part. The existence of the relationship itself is what makes the marriage void.

Are children born of a marriage void under Article 37 or 38 considered legitimate?

No. Article 54 limits legitimate status to children conceived or born before finality of a judgment under Article 36, and to children of certain Article 53 subsequent marriages. It does not extend that status to children of a marriage void under Article 37 or 38, who are illegitimate.

Do we still need to go to court if the marriage is already void by law?

Generally, yes, if either party intends to remarry or needs the void status reflected on official civil-registry records. Article 40 requires a final court judgment declaring the marriage void before that nullity can be invoked for purposes of remarriage.

Is there a deadline for filing a case to declare the marriage void under these articles?

No. Under Article 39, as amended by Republic Act No. 8533, the action or defense for declaration of absolute nullity of a marriage does not prescribe.

Related Guides

Sources and Legal Citations

Statutes and codes

  • Family Code of the Philippines, Executive Order No. 209 (1987), Arts. 35, 37, 38, 39 (as amended by Republic Act No. 8533), 40, 54, 147–148 — full text via LawPhil

Supreme Court rules and jurisprudence

  • A.M. No. 02-11-10-SC, Rule on Declaration of Absolute Nullity of Void Marriages and Annulment of Voidable Marriages (2003) — full text via LawPhil

Official agency material

  • Philippine Statistics Authority, Annotation on the Annulment/Declaration of Nullity of Marriage — psa.gov.ph

Sources rechecked as of: September 18, 2026

This article is general legal information for the Philippines and is not legal advice. Procedures described here are drawn from the applicable Family Code provisions, Supreme Court rule, and official agency information; individual courts and offices may apply additional local practices. For advice about your specific situation, consult a Philippine lawyer or, if you qualify, the Public Attorney’s Office.

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