Quick answer

Yes. Marriage between first cousins is generally legal in the Philippines because it is not among the marriages expressly prohibited by law. The Philippine rules on prohibited marriages focus on (1) incestuous relationships (very close blood relations) and (2) relationships against public policy (a broader set that includes certain in-law, adoptive, and step-family relationships). First cousins are not included in either prohibition.

That said, legality can still be affected by other requirements and impediments (age, prior existing marriage, capacity, license, authority of the solemnizing officer, and related formalities).

The governing law

In the Philippines, the principal law on marriages and impediments is the Family Code of the Philippines (Executive Order No. 209, as amended). It sets out:

Essential requisites of marriage (what makes a marriage valid in substance)
Formal requisites (what makes it valid in form)
Void marriages (invalid from the start)
Voidable marriages (valid until annulled)
Prohibited marriages (incestuous, or contrary to public policy)

The question “Are first cousins allowed to marry?” is answered primarily by the provisions on prohibited marriages—especially the articles enumerating incestuous marriages and marriages against public policy.

Why first-cousin marriage is generally legal

Philippine law does not prohibit marriage between relatives merely because they share a grandparent. The Family Code prohibits marriages within specified degrees:

Incestuous marriages (closest blood relationships), and
Marriages against public policy (a list that includes some collateral relatives more distant than siblings, plus certain affinity/adoption/step relationships).

First cousins are collateral relatives in the fourth civil degree (you → parent (1) → grandparent (2) → aunt/uncle (3) → cousin (4)). The prohibitions do not reach that far in the bloodline for cousins.

So, unless another legal impediment exists, first cousins can validly marry.

Civil degrees of relationship (Philippine method)

The Family Code uses the civil-law system of computing degrees in the collateral line:

Count up from one person to the common ancestor, then down to the other person.
Each generational step is one degree.

Examples:

Parent–child: 1st degree (direct line)
Siblings: 2nd degree (collateral)
Uncle/Aunt–Niece/Nephew: 3rd degree (collateral)
First cousins: 4th degree (collateral)
Second cousins: 6th degree (collateral)

This matters because the Family Code’s “public policy” prohibition for blood relatives in the collateral line typically stops at the fourth civil degree, but in practice it targets relationships like uncle/aunt with niece/nephew (3rd degree). First cousins are 4th degree, and are not listed among the prohibited blood relations in the code’s prohibited marriage provisions as applied in Philippine family law practice and doctrine.

Prohibited marriages in the Philippines

A. Incestuous marriages (void from the beginning)

These are marriages between persons related within very close consanguinity (blood). They are void ab initio—treated as if they never existed—and generally cannot be “cured” by later consent, cohabitation, or good faith.

Incestuous marriages include those between:

Ascendants and descendants of any degree
- Parent and child
- Grandparent and grandchild
- Great-grandparent and great-grandchild, etc.
Brothers and sisters, whether:
- Full blood, or
- Half blood

First cousins are not ascendants/descendants of each other and are not siblings, so they do not fall under incestuous marriages.

B. Marriages “against public policy” (void from the beginning)

These are also void ab initio. The Family Code identifies specific relationships where marriage is forbidden because it is considered contrary to public policy. This category includes:

1) Certain blood relationships in the collateral line

Philippine law prohibits marriage between relatives in the collateral line within a specified closeness (classically capturing uncles/aunts with nieces/nephews). First cousins are not treated as covered by the public-policy prohibition in Philippine family law.

In practical terms, if the relationship is:

Uncle/Aunt and Niece/Nephew → prohibited
First cousins → generally not prohibited

2) Certain relationships by affinity (in-laws)

Affinity means relationship created by marriage (in-laws). Some marriages are prohibited, such as those involving:

A person and the spouse of their child (e.g., father-in-law with daughter-in-law)
A person and the spouse of their parent (e.g., step-parent scenarios that can overlap with affinity)
A person and the spouse of their adopted child, and similar close in-law ties

These prohibitions are meant to prevent marriages that are considered socially disruptive because they overlap with core family roles.

3) Adoption relationships

Adoption creates a legal parent-child relationship. Prohibitions cover marriages such as:

Adopter and adopted child
Adopted child and surviving spouse of adopter
Adopter and surviving spouse of adopted child
Adopted child and legitimate child of adopter (treated similarly to siblings for policy reasons)

These are void as against public policy even if there is no blood relation.

4) Step-family relationships

Certain step relationships are prohibited where the law considers the family roles too close (even if not by blood).

So: first cousins specifically

1) First cousins by blood

Legal in the Philippines, provided all other marriage requirements are met.

2) “Cousins” by half blood / blended families

People sometimes say “first cousin” loosely. The legal question depends on how you are related:

If you are truly first cousins by blood (parents are siblings), the marriage is generally legal.
If you are related through adoption or step relationships in a way that falls under “public policy” prohibitions, legality can change.

3) Cousins by affinity (“pinsan” through marriage)

Being “cousins” through marriage is not the same as blood cousins. The relevant issue becomes whether the relationship falls into a prohibited affinity category. Most cousin-by-marriage scenarios do not automatically create a prohibited affinity relationship, but some specific in-law relationships are prohibited.

Other marriage requirements that still matter (even if you’re first cousins)

Even if your relationship is not prohibited, the marriage may still be void or voidable depending on other rules.

A. Essential requisites (substance)

A valid marriage requires:

Legal capacity of the contracting parties (e.g., of age, not already married, not within prohibited relationships), and
Consent freely given in the presence of the solemnizing officer.

If either essential requisite is absent, the marriage can be void or voidable, depending on the defect.

B. Formal requisites (form)

A valid marriage generally requires:

Authority of the solemnizing officer
A valid marriage license (except in specific exempt cases)
Marriage ceremony with personal appearance of both parties and declaration that they take each other as spouses, with at least two witnesses of legal age.

Missing formal requisites can make the marriage void, subject to limited exceptions (e.g., some defect situations where good faith is recognized in narrow contexts).

Common legal pitfalls for cousin couples (and any couples)

1) Prior existing marriage

If either party is still validly married, the subsequent marriage is void (bigamous), unless the prior marriage has been judicially declared void or dissolved/annulled as required by law.

2) Age and parental consent/advice rules

Philippine law imposes:

Minimum age requirements for marriage capacity
Additional requirements (parental consent or parental advice) within certain age ranges (as provided by the Family Code and related regulations)

Failure to comply can lead to voidable status in some situations or administrative/registration problems.

3) Psychological incapacity or other void/voidable grounds

Separate from prohibited relationships, marriages can be challenged due to:

Psychological incapacity
Fraud, force, intimidation, undue influence
Impotence, serious sexually transmissible disease under certain conditions
Lack of consent or vitiated consent

These issues apply regardless of cousin status.

4) Marriage license issues

A marriage license is generally required unless the couple qualifies for an exemption (e.g., certain long cohabitation scenarios under the Family Code). Improper licensing can jeopardize the marriage.

Registration and documentation (practical Philippine context)

Local Civil Registrars typically require:

Birth certificates (often PSA-issued)
CENOMAR or advisory on marriages (PSA)
Marriage license (or proof of exemption, if applicable)
IDs and other standard documents

For first cousins, some couples worry that the Local Civil Registrar will refuse the application. In practice, what matters is that the relationship is not within the prohibited degrees. If an officer raises questions, the issue usually comes down to clarifying the relationship and ensuring it is not an uncle–niece or similarly prohibited relationship mistakenly described as “cousins.”

Health, genetic counseling, and “legality” (separate issues)

The law’s allowance does not eliminate medical considerations. Some couples choose genetic counseling due to increased risk of certain recessive conditions in offspring of close biological relatives. This is a health consideration rather than a marriage validity requirement.

Frequently asked questions

Is marriage between first cousins void or voidable?

Neither, as a general rule. It is valid, assuming compliance with essential and formal requisites and absence of other impediments.

Are second cousins allowed?

Yes. If first cousins are allowed, second cousins are also not within prohibited degrees and are generally allowed.

Is marriage between an uncle and a niece legal?

No. That relationship falls within the prohibited degrees and is treated as void.

Does the Catholic Church rule control civil legality?

No. Church rules may affect whether a church will solemnize the marriage, but civil legality is governed by Philippine civil law. A marriage may be civilly valid even if a religious authority refuses to officiate.

Can a first-cousin marriage be refused by a solemnizing officer?

A solemnizing officer may decline to officiate for personal/religious reasons, but that does not change civil legality. The couple may seek another authorized solemnizing officer, provided legal requisites are met.

Summary

First-cousin marriage is generally legal in the Philippines because it is not among the prohibited marriages under the Family Code.
Prohibited marriages fall into:
- Incestuous marriages (ascendants/descendants; siblings), and
- Marriages against public policy (including uncle/aunt with niece/nephew; certain in-law, adoptive, and step-family relationships).
Even if first cousins may marry, the marriage must still comply with capacity, consent, license, authority, and ceremony requirements, and must not be barred by other impediments (e.g., prior existing marriage).