In the Philippines, the legal framework for "common-law" marriages—properly referred to as unions without marriage or cohabitation—is primarily governed by the Family Code of the Philippines. Unlike a valid marriage, which is governed by the absolute community of property or conjugal partnership of gains, cohabiting couples fall under specific provisions depending on whether there are legal impediments to their marriage.

I. Classification of Common-Law Unions

The rights of the parties are determined by their legal capacity to marry each other. The Family Code distinguishes between two types of informal unions:

1. Unions Without Legal Impediment (Article 147)

This applies to a man and a woman who are:

Capacitated to marry each other (i.e., no legal obstacles like an existing marriage, age requirements are met, and they are not related by blood).
Live exclusively with each other as husband and wife.
Without the benefit of marriage or under a void marriage.

2. Unions With Legal Impediment (Article 148)

This applies to couples who cohabit but are:

Incapacitated to marry each other (e.g., one or both are still legally married to someone else, or the relationship is incestuous).
In a "bigamous" or "adulterous" relationship.

II. Property Ownership Rules

Under Article 147 (No Impediment)

The law presumes a special co-ownership. The rules are as follows:

Wages and Salaries: Owned in equal shares by both parties.
Property Acquired by Both: Properties acquired through their joint efforts, work, or industry are owned in common in equal shares.
The "Care and Maintenance" Rule: If one party does not earn a salary but manages the household and cares for the family, they are deemed to have contributed to the acquisition of property. Thus, they still own a 50% share.
Presumption of Joint Acquisition: Property acquired while living together is presumed to have been obtained by joint effort, unless proven otherwise.
Disposal of Property: Neither party can sell or encumber their share of the common property inter vivos (during their lifetime) without the consent of the other until the cohabitation is terminated.

Under Article 148 (With Impediment)

The rules are much stricter because the law does not want to reward "illegal" unions at the expense of a legitimate spouse.

Actual Contribution Only: Only the properties acquired by both of them through their actual joint contribution of money, property, or industry shall be owned by them in common.
No Presumption of Equality: Shares are in proportion to their actual contribution. If one party cannot prove their financial contribution, they own nothing.
Household Care: Unlike Article 147, "care and maintenance of the family" does not count as a contribution here.
Forfeiture: If one party is validly married to another, their share in the co-ownership generally accrues to the absolute community or conjugal partnership of the existing valid marriage.

III. Rights of Children

The legal status of children born in common-law marriages is "illegitimate." However, they possess specific rights under the law:

Support: Children are entitled to support (food, shelter, medical care, education) from both parents.
Succession: Illegitimate children are legal heirs. Under the Civil Code, their legitime (inheritance) is generally one-half (1/2) of the legitime of a legitimate child.
Surnames: Under Republic Act No. 9255, illegitimate children may use the surname of their father if the father has formally recognized the child through the record of birth or a private handwritten instrument.
Custody: Generally, the mother exercises sole parental authority and custody over illegitimate children, even if the father recognizes them.

IV. Succession and Inheritance

In common-law unions, the "partners" are not legal heirs of one another.

No Intestate Succession: If one partner dies without a will, the surviving common-law partner does not inherit from the deceased by law. The estate goes to the deceased's children, parents, or collateral relatives.
Testamentary Succession: A partner may leave property to the other through a Last Will and Testament, provided it does not impair the "legitime" (the portion reserved by law) of the deceased's compulsory heirs (like children).

V. Summary Table of Property Regimes

Feature	Article 147 (Capacitated)	Article 148 (Incapacitated)
Salaries/Wages	Owned 50/50	Owned by the earner only
Household work	Counted as contribution	Not counted
Presumption	Equal 50/50 ownership	No presumption; must prove contribution
Requirement	Exclusive cohabitation	Cohabitation
Forfeiture	None	Possible forfeiture to legitimate spouse