Philippine civil law recognizes children—whatever their status at birth—as compulsory heirs of their parents. That means parents cannot freely dispose of their entire estate because the law reserves portions (“legitimes”) for certain heirs, including children. What follows is a practical, doctrine-grounded overview of how children’s inheritance works in both testate (with a will) and intestate (no will) successions, focusing on the differences between legitimate and illegitimate children.

1) Key terms and classifications

Legitimate child – conceived or born during a valid marriage, or legitimated by the subsequent valid marriage of the parents. Legitimation generally retroacts to birth for civil effects, including succession.
Illegitimate child – conceived and born outside a valid marriage. The Family Code collapses older labels (“natural,” “spurious”) into this single class.
Adopted child – for succession, treated as a legitimate child of the adopter.
Compulsory heirs – heirs whom the law cannot deprive of their legitime except for legally recognized causes of disinheritance. Children (legitimate and illegitimate) and the surviving spouse are compulsory heirs; in default of legitimate descendants, legitimate parents/ascendants become compulsory heirs.

Filiation matters. An illegitimate child must establish filiation (e.g., civil registry entries; admission of parentage; open and continuous possession of the status of a child). Once established, rights to support and succession follow.

2) Two ways estates pass: with a will vs. without a will

A. Testate succession (with a will)

The testator may only dispose of the free portion.
The legitime is reserved by law for compulsory heirs.
Children (and, where applicable, the surviving spouse and legitimate ascendants) must receive at least their legitime. A will that impairs legitimes is reducible to preserve them.

B. Intestate succession (no will)

The law fixes who inherits and in what order.
Legitimate children and descendants inherit first (together with the surviving spouse).
Illegitimate children are also heirs and participate subject to rules below.
Legitimate ascendants, collateral relatives, and the State come into play only when nearer heirs do not exist.

3) Core rules affecting children’s shares

3.1 Legitimate children

They are primary compulsory heirs.
If any legitimate child or descendant exists, legitimate ascendants (parents/grandparents) are excluded.
Their collective legitime equals a fixed fraction of the estate (classically, one-half of the hereditary estate, divided equally among them). The surviving spouse has a separate legitime that coexists with the children’s rights.

3.2 Illegitimate children

They are compulsory heirs of their parents.
Their legitime is proportionally smaller than that of legitimate children (traditionally set at one-half of the legitime of a legitimate child).
They inherit alongside legitimate children and the surviving spouse, but subject to:
- the reduction principle (free portion is exhausted first before touching legitimes), and
- the “iron curtain rule” (see §3.4).

3.3 Adopted and legitimated children

Adopted children inherit as legitimate children of the adopter. (Their ties to the biological family for succession may be affected by the specific adoption statute in force at the time, but as to the adopter, treat as legitimate.)
Legitimated children (by the parents’ subsequent valid marriage) are treated as legitimate for succession, generally retroactive to birth.

3.4 The “iron curtain rule” (Civil Code Art. 992)

There is no intestate succession between an illegitimate child and the legitimate relatives of his/her parent.
Practical effect: an illegitimate child cannot inherit ab intestato from the legitimate siblings, parents, or other legitimate relatives of the father/mother; nor can those legitimate relatives inherit intestate from the illegitimate child.
This rule does not prevent the parent (whether legitimate or not) from leaving a will in favor of an illegitimate child within the free portion, nor does it block succession between the child and the parent themselves (only between the illegitimate child and the parent’s legitimate relatives).
Representation by illegitimate descendants follows special limits (see §4.3).

4) Participation, representation, and typical combinations

4.1 When there are legitimate children and illegitimate children

All such children are compulsory heirs of the decedent-parent.
Legitimate children take their fixed legitime first.
Illegitimate children take a smaller, legally defined legitime (traditionally half of a legitimate child’s legitime).
The surviving spouse is also a compulsory heir with a distinct legitime.
If the free portion is insufficient to satisfy the illegitimate children’s legitimes (after assigning legitimes to legitimate children and the spouse), the law authorizes proportionate reductions so that all legitimes (not mere hopes) are preserved in their legal ratios.

4.2 When there are only illegitimate children (no legitimate children/descendants)

Illegitimate children share the estate among themselves as compulsory heirs, together with the surviving spouse (if any), applying the statutory legitime rules.
Legitimate ascendants (parents/grandparents) do not exclude an illegitimate child from inheriting from his/her own parent.

4.3 Representation by descendants (grandchildren)

Representation lets a descendant step into the place of a predeceased, disinherited, or incapacitated heir.
Legitimate descendants represent legitimate ascendants in the direct line.
Illegitimate descendants may represent an illegitimate parent to succeed from the decedent grandparent who was also in an illegitimate line, but the iron curtain rule blocks intestate transmission between an illegitimate descendant and the legitimate relatives of the parent.
Wills can override intestacy within the free portion, but not to impair the legitimes of compulsory heirs.

5) Proof of status (filiation) and timing

Establishing filiation is essential, especially for an illegitimate child. Usual modes include:
- Civil registry records (birth certificates reflecting filiation),
- Public documents or admissions of filiation,
- Open and continuous possession of the status of a child.
When evidence must be produced: actions to claim recognition/filiation have strict rules on who may sue and when (some must be brought during the alleged parent’s lifetime, with recognized exceptions).
Paternity/maternity suits interact with estate proceedings; courts may suspend or coordinate cases to resolve filiation before final distribution.

6) The surviving spouse, collation, and reductions

The surviving spouse is a compulsory heir with a separate legitime that coexists with the children’s.
Donations made by the decedent during lifetime may be subject to collation (brought into the mass for computation) to check whether they impaired legitimes.
If a will or lifetime gifts exceed the disposable free portion, reduction applies in legal order: free portion first, then donations in reverse order, etc., until legitimes are intact.

7) Disinheritance and unworthiness (rare but important)

Children—legitimate or illegitimate—may be disinherited only for causes expressly provided by law (e.g., serious offenses against the testator, violence, grave insults, etc.).
Disinheritance must be in a will, stating a specific legal cause.
A disinherited heir’s descendants may represent him/her (subject to the iron curtain rule limits) and thus still inherit.

8) Practical illustrations (high-level, simplified)

These are illustrative, not calculators. Real cases adjust for exact facts, number of heirs, donations, debts, and tax.

Decedent leaves: surviving spouse + 2 legitimate children + 1 illegitimate child.
- Legitimate children: take the primary legitime class.
- Spouse: has a distinct legitime alongside the children.
- Illegitimate child: receives a smaller legitime (traditionally half of a legitimate child’s legitime).
- If the estate’s free portion is too small, the law reduces dispositions so all legitimes fit.
Decedent leaves: 1 illegitimate child + spouse; no legitimate children.
- Illegitimate child and spouse are both compulsory heirs; they share under the applicable legitime proportions.
- Legitimate parents do not push out the child from inheriting from his/her own parent.
Decedent leaves: 2 legitimate children; no spouse; 1 grandchild by a predeceased illegitimate child.
- Legitimate children inherit; the grandchild’s right to represent depends on whether representation is allowed within the illegitimate line and whether the iron curtain rule is triggered (watch this carefully in mixed legitimate/illegitimate lines).

9) Common pitfalls and practice tips

Do not assume “all children share equally.” The law distinguishes legitimate and illegitimate lines and protects legitimes in fixed ratios.
Always verify status (legitimate, illegitimate, adopted, legitimated) and filiation proof before computing shares.
Check for a will, lifetime donations, and debts; these can materially change distributable values and trigger reduction or collation.
Watch the iron curtain rule in intestacy—it is frequently overlooked in mixed families.
For adopted children, apply the current adoption law in force at the time of adoption to confirm the precise successional ties.
Tax (estate tax, deadlines, exemptions) is separate from civil-law shares—settle both civil and tax sides properly.

10) Bottom line

Legitimate children are the primary compulsory heirs; illegitimate children are also compulsory heirs but receive a smaller legitime by statute.
The surviving spouse co-inherits with children and has an independent legitime.
The iron curtain rule blocks intestate succession between an illegitimate child and the legitimate relatives of the parent, but a will may leave them up to the free portion.
Exact computations turn on who survives, how filiation is proved, and whether there’s a will or donations.

This article provides a high-level legal framework under Philippine civil law. For any real case—especially those involving mixed legitimate/illegitimate lines, adoption/legitimation, prior donations, or a contested will—get tailored advice from a Philippine lawyer and review the most recent statutes and Supreme Court rulings before computing shares.