In the Philippines, succession and inheritance are governed strictly by the Civil Code and the Family Code. Property rights following a person's death depend heavily on the legal nature of the relationship between the deceased and the surviving partner.

Philippine law draws a sharp, uncompromising distinction between a legal spouse and a common-law partner (live-in partner). While the law heavily protects the legal spouse, it offers virtually no automatic inheritance rights to a common-law partner, leaving the latter to rely on property ownership laws rather than the laws of succession.

1. The Inheritance Rights of a Legal Spouse

Under Philippine law, a legal spouse is a person bound to the deceased by a valid marriage. The legal spouse is classified as a compulsory heir under Article 887 of the Civil Code. This means they cannot be deprived of their share of the estate (called the legitime) except through a valid legal disinheritance for specific causes provided by law.

Testate Succession (When There is a Will)

If the deceased left a valid Last Will and Testament, they can only dispose of the "free portion" of their estate. The legal spouse is guaranteed their legitime, which varies depending on who else survives alongside the spouse:

Surviving with One Legitimate Child: The child gets $1/2$ of the estate; the legal spouse gets $1/4$.
Surviving with Two or More Legitimate Children: The legitimate children share $1/2$ of the estate equally; the legal spouse is entitled to a share equal to the legitime of each legitimate child (taken from the free portion).
Surviving with Legitimate Parents Only: The parents get $1/2$ of the estate; the legal spouse gets $1/4$.
Surviving Alone: The legal spouse’s legitime is $1/2$ of the entire estate.

Intestate Succession (When There is No Will)

If a person dies without a will, the law dictates how the estate is distributed. The legal spouse fares significantly better in intestacy:

Surviving Heirs	Share of the Legal Spouse	Share of Other Heirs
Spouse + 1 Legitimate Child	$1/2$ of the estate	$1/2$ of the estate
Spouse + Multiple Legitimate Children	Equal share with one child (Estate is divided equally among children + spouse)	Equal shares among the children
Spouse + Legitimate Parents	$1/2$ of the estate	$1/2$ of the estate
Spouse + Illegitimate Children	$1/2$ of the estate	$1/2$ of the estate (divided among them)
Spouse Alone	$100%$ of the estate	None

Note on Legal Separation: A legally separated spouse can still inherit if the deceased died intestate, provided the deceased was the one at fault for the separation. If the surviving spouse was the guilty party, they lose all rights to inherit from the innocent spouse by operation of law.

2. The Inheritance Rights of a Common-Law Partner

Under Philippine law, a common-law partner is NOT a compulsory heir. No matter how many decades a couple lived together, and regardless of whether they have children, a surviving live-in partner has zero automatic rights to inherit the estate of the deceased partner under the laws of succession.

If a common-law partner dies without a will (intestate), their entire estate passes to their blood relatives (children, parents, siblings, etc.). The surviving partner receives nothing from the estate via inheritance.

However, a common-law partner is not completely left without remedies. Their rights are protected through Property Co-ownership and Testamentary Dispositions, subject to strict conditions.

A. Property Co-ownership (Family Code Framework)

Instead of inheriting property, a surviving common-law partner may claim rights over assets based on the rules of co-ownership during their cohabitation. The rules differ based on whether the partners had any legal impediments to marry.

Article 147: Couples Capacitated to Marry

This applies to a man and a woman who live together exclusively as husband and wife but without the benefit of marriage, provided both are legally free to marry (e.g., neither is currently married to someone else).

Presumption of Equal Sharing: Properties acquired during the cohabitation are presumed to be owned in equal ($50/50$) shares.
Wages and Salaries: All wages and salaries earned by either partner during the cohabitation belong to them in equal shares.
Care and Maintenance of the Home: If one partner did not earn materially but took care of the household and the family, the law deems this effort as a contribution, granting them an equal share in the properties acquired during that period.
Upon Death: The surviving partner does not "inherit" the deceased’s $50%$ share. Rather, the surviving partner simply retains their own $50%$ share because it already belongs to them. The deceased partner's $50%$ share goes to the deceased's legal heirs (such as their children or parents).

Article 148: Couples with Legal Impediments to Marry

This applies to situations where the cohabitation is adulterous or bigamous (e.g., one or both partners are still legally married to other people).

No Presumption of Equality: Only properties acquired through actual joint contribution of money, property, or industry will be co-owned.
Proof Required: The surviving partner must present concrete proof (receipts, bank records, land titles) of their actual financial contribution. If they cannot prove they paid for a portion of the asset, it will be considered part of the deceased's estate.
Household Care Excluded: Efforts in managing the household do not count as a contribution under Article 148.
Crucial Exception: If one partner is still legally married, their share in the co-owned property may be legally claimed by their lawful spouse and legitimate children.

B. Testamentary Dispositions (Leaving a Will)

A person can choose to leave a portion of their estate to a common-law partner by executing a Last Will and Testament. However, this is subject to two major legal barriers:

Impairment of Legitime: The legacy given to the common-law partner can only come from the "free portion" of the estate. It cannot reduce or impair the legitime of the deceased’s compulsory heirs (such as biological or adopted children).
The Adultery/Concubinage Bar: Under Article 1028 in relation to Article 739 of the Civil Code, testamentary dispositions (wills) made between persons who are guilty of adultery or concubinage at the time of the designation are void.

If a person is legally married to someone else but leaves property to their live-in partner in a will, the legal spouse or legitimate children can challenge the will in court to void the donation.

Summary of Core Differences

Feature	Legal Spouse	Common-Law Partner
Status as Compulsory Heir	Yes	No
Entitled to Legitime	Yes	No
Inheritance without a Will	Yes (Entitled to $1/2$ to $100%$ of estate)	No (Entitled to $0%$)
Can Be Disinherited?	Only through specific, strict legal grounds	Not applicable (cannot inherit by default)
Property Claims upon Death	Liquidation of absolute community/conjugal partnership properties	Separation of co-owned properties under Art. 147 or 148
Can Receive via a Will?	Yes	Only from the free portion, and only if neither partner is legally married to someone else.