In Philippine law, the rights of children to inherit from their parents are fundamental, rooted in the principles of family solidarity and compulsory succession. While the 1987 Constitution guarantees equal protection of the law, the Civil Code and Family Code maintain a distinction between legitimate and illegitimate children in terms of inheritance shares. Illegitimate children—those born outside of a valid marriage—are entitled to inherit from their father, but their shares are generally half of those accorded to legitimate children. This article comprehensively examines the legal basis, establishment of filiation, specific rights to the estate, differences in testate and intestate succession, procedural requirements, and other relevant considerations.

Legal Framework

The primary laws governing this topic are:

The Civil Code of the Philippines (Republic Act No. 386), particularly Book III on Succession (Articles 774 to 1105), which defines compulsory heirs and legitimes.
The Family Code of the Philippines (Executive Order No. 209, as amended), which regulates filiation, paternity, and family relations (Articles 163 to 182 on paternity and filiation).
Related laws include Republic Act No. 9255 (An Act Allowing Illegitimate Children to Use the Surname of Their Father), which facilitates recognition but does not alter inheritance shares.
The Rule on DNA Evidence (A.M. No. 06-11-5-SC) aids in proving filiation.
The 1987 Constitution (Article XV) emphasizes the family's role and the rights of children.

Illegitimate children are recognized as compulsory heirs under Article 887 of the Civil Code, alongside legitimate children, surviving spouses, and (in default of descendants) legitimate ascendants.

Definition and Classification of Illegitimate Children

Article 163 of the Family Code defines illegitimate children as those conceived and born outside a valid marriage. This encompasses children born to parents who are not married to each other at the time of conception and birth, including those from adulterous relations or marriages later declared void. The Family Code eliminated earlier distinctions under the Civil Code between “natural” and “spurious” children, treating all children born out of wedlock uniformly as illegitimate once filiation is established.

Establishing Filiation: The Prerequisite for Inheritance Rights

For an illegitimate child to claim rights as a beneficiary, filiation to the deceased father must be established. Filiation refers to the blood relationship between parent and child.

Modes of establishing filiation:

Voluntary Recognition: The father acknowledges the child through:
- A statement in the child's birth certificate.
- A public document (e.g., notarial acknowledgment).
- A private handwritten instrument signed by the father, acknowledging the child as his.
- Under RA 9255, this allows the child to use the father's surname.
Compulsory or Judicial Recognition: If the father does not voluntarily recognize, the child may file a petition for recognition in court. Evidence may include:
- Continuous possession of the status of a child (e.g., the father treated the child as his).
- DNA testing, which has become a strong evidentiary tool.
- Other proofs like letters, photos, or witness testimonies showing acknowledgment.

Under Article 175 of the Family Code, the action to establish filiation of illegitimate children is brought in the same manner and using the same evidence as legitimate children. The action to establish filiation must generally be filed during the lifetime of the child. If the putative father dies before recognition, the action may be filed against his estate or representatives. Posthumous claims are permitted, and once filiation is established, the rights attach with retroactive effect for inheritance purposes.

Rights as Compulsory Heirs and Legitime

Illegitimate children are compulsory heirs, meaning the father cannot deprive them of their legitime (the portion of the estate reserved by law) except for valid grounds of disinheritance.

Calculation of Legitime:

The legitime of legitimate children and descendants collectively is one-half (1/2) of the hereditary estate (Civil Code, Article 888).
Each illegitimate child's legitime is one-half (1/2) of the legitime of each legitimate child (Civil Code, Article 895).

Examples:

Estate value: ₱1,000,000. One legitimate child, one illegitimate child.
- Legitimate child's legitime: ₱500,000.
- Illegitimate child's legitime: ₱250,000 (half of ₱500,000).
- Total legitime reserved: ₱750,000.
- Free portion: ₱250,000 (disposable by will).
Estate value: ₱1,000,000. Two legitimate children, one illegitimate child.
- Each legitimate child's legitime: ₱250,000 (₱500,000 / 2).
- Illegitimate child's legitime: ₱125,000.
- Total legitime for children: ₱625,000.
- Free portion: ₱375,000.

When there are no legitimate children but only illegitimate children, they collectively reserve one-half (1/2) of the estate as their legitime, to be divided equally. In intestate succession (discussed below), they receive the entire net estate.

The surviving spouse's legitime is equal to that of a legitimate child when there are children, further affecting the computation.

Disinheritance: A father may disinherit an illegitimate child only for specific causes enumerated in the Civil Code (Articles 919-920 for descendants), such as:

Attempt against the life of the parent.
Maltreatment or serious physical injury.
Conviction for a crime involving moral turpitude.
Refusal to support the parent when needed. Disinheritance must be expressly made in a will, stating the cause. If the cause is not proven, the disinheritance is void and the child recovers the legitime.

Testate Succession (With a Will): The deceased may dispose of the free portion of his estate freely via a valid will, subject to formalities (Articles 783-837). However, legitimes must be respected. Illegitimate children are entitled to their legitime regardless of the will, unless validly disinherited. The will can provide additional shares from the free portion but cannot reduce below the legitime. Omission of an illegitimate child in the will does not extinguish their right; they may demand their legitime through appropriate action.

Intestate Succession (Without a Will): In the absence of a will, the estate is distributed according to the rules in Articles 960-1014 of the Civil Code.

Legitimate and illegitimate children concur as heirs.
Each legitimate child receives twice the share of each illegitimate child.
If no legitimate children exist, illegitimate children inherit the entire net estate in equal shares.
The surviving spouse inherits a share equal to that of a legitimate child, sharing concurrently.
Ascendants or collaterals inherit only in default of descendants.

Example: Estate ₱1,000,000; 2 legitimate children, 2 illegitimate children, no spouse.

Total "shares": Legitimate get 2 units each (4 units), illegitimate get 1 unit each (2 units) = 6 units total.
Each unit: ₱1,000,000 / 6 ≈ ₱166,667.
Each legitimate: ₱333,333.
Each illegitimate: ₱166,667.

This proportional distribution applies to the entire estate in intestacy. Collation of donations or advances made during the father's lifetime may apply to equalize shares.

Procedural Aspects in Estate Settlement

Testate Proceedings: The will is submitted for probate in the Regional Trial Court. Known heirs, including illegitimate children whose filiation is established, must be notified. Unrecognized children may file a separate petition to establish filiation and claim their legitime.
Intestate Proceedings: Petition for letters of administration or settlement of estate. Heirs include all children with proven filiation.
Extrajudicial Settlement: Possible if no debts and all heirs agree (for small estates or amicable cases), via public instrument. Illegitimate children must be included or their shares provided for.
Claiming Shares: If omitted, the child can:
- File an action for declaration of heirship and claim of legitime.
- Intervene in ongoing estate proceedings.
- Action to annul partition if estate already distributed.

Prescriptive periods:

For filiation: Generally during the child's lifetime, with exceptions when based on written acknowledgment.
For recovery of inheritance share: 30 years for real property, 10 years for personal property, from the time the right accrues (e.g., death of father).

DNA evidence can be crucial in contested cases. The court may order testing on remains or relatives.

Other Considerations

Legitimation: If the parents marry after the child's birth, the illegitimate child is legitimated and acquires the status of a legitimate child, entitling him/her to full shares (Family Code, Articles 177-182). This must be recorded.
Adoption: An adopted child is treated as legitimate.
Rights Beyond Inheritance: Illegitimate children have rights to support from the father during his lifetime (Family Code). They can also inherit from the mother's side fully as her children.
Estate Taxes and Debts: Shares are from the net estate after debts, taxes, and funeral expenses. All heirs share proportionally in liabilities if applicable.
Special Cases: Children born from void marriages may be considered legitimate or illegitimate depending on good faith. Children of concubines or common-law partners are illegitimate but entitled if filiation proven.
Muslim Filipinos: Governed by the Code of Muslim Personal Laws (PD 1083), which may have different rules on inheritance and filiation; consult specific provisions.

Challenges and Reforms

Proving filiation without voluntary acknowledgment can be challenging, especially with the passage of time. DNA has helped many cases. Legislative proposals have been discussed to equalize shares between legitimate and illegitimate children to further promote equality, but as of current law, the distinction persists.

Illegitimate children in the Philippines have substantial rights to their father's estate once filiation is established. They are protected as compulsory heirs with defined legitimes, ensuring minimum shares in both testate and intestate succession.