In Short
- A child becomes legitimate (legitimation) when the parents later validly marry each other (Family Code Art. 178).
- It works only if nothing in the law stopped the parents from marrying each other when the child was conceived, such as one of them already being married.
- RA 9858 (2009) also allows it when the only reason the parents could not marry was that one or both were under 18.
- Both parents sign a sworn statement together (a Joint Affidavit of Legitimation), which is registered with the civil registrar within 30 days.
- The child then has the same rights as a child born to married parents, counted from birth.
Who Can Be Legitimated
Not every child born before the parents married can be legitimated. Under Article 177 of the Family Code, as amended by Republic Act No. 9858 (RA 9858), a child may be legitimated if:
- the child was conceived and born outside of marriage;
- at the time of conception, nothing in the law stopped the parents from marrying each other (no impediment), or were disqualified only because one or both of them were below 18 years old; and
- the parents later entered into a valid marriage with each other.
An impediment means a legal reason two people cannot marry. The most common one is that one parent was still married to someone else when the child was conceived. In that case the child cannot be legitimated, even if the parents marry later after the first marriage ends. The child stays illegitimate (legally, a child of unmarried parents) but can still use the father's surname if he acknowledges them. See using the father's surname. Adoption is another way in some situations. See adoption.
What Legitimation Does
- Same rights. A legitimated child has the same rights as a legitimate child (Art. 179), including the right to use the father's surname and a full share of inheritance as a legitimate child.
- From birth. The effects go back to the time of the child's birth (Art. 180).
- Not undone by annulment. If the parents' marriage is later annulled (cancelled by a court) as voidable, the legitimation stays (Art. 178).
- For a child who has died. Legitimation of a child who died before the wedding benefits that child's own children and grandchildren (Art. 181).
- Challenges. Only people whose rights are harmed by it can question a legitimation, within five years from when their right to sue arises (Art. 182).
How It Is Done
The PSA's rules for RA 9858 (Administrative Order No. 1, Series of 2010) give the steps:
- Marry. The parents marry each other in a valid marriage.
- Sign a Joint Affidavit of Legitimation. Both parents sign it under oath. If one parent has died or been declared presumed dead by a court, the surviving parent signs. The affidavit states the parents' names and address, the date and place of the marriage and who officiated it, the child's name and date and place of birth, and that the parents had no impediment to marry each other at conception (other than age), and later married.
- Register it within 30 days. File the affidavit with the local civil registry office of the place where the child was born. A parent, the child if 18 or older, or someone they authorize may file. If the child was born abroad, it goes to the Office of the City Civil Registrar of Manila.
- Annotation (a note on the record). The civil registrar records the legitimation and adds a note to the child's birth record. The original entries on the Birth Certificate are not erased. The PSA copy will carry the note, and on the civil registrar's certified transcription (its official typed copy) the child's surname becomes the father's and the middle name becomes the mother's maiden surname.
If both parents died without signing the affidavit, the child (or a guardian, for a minor) must go to court.
If the parents live abroad, the affidavit is signed before or certified by the Philippine embassy or consulate, then sent home for registration.
Once the record reaches the PSA, ask for a new copy of the Birth Certificate. See PSA certificates.
Legitimation, the Father's Surname, or Adoption
These three are often confused:
| Route | When It Fits | Child's Status After |
|---|---|---|
| Legitimation | The parents later marry each other and nothing (other than age) stopped them from marrying at conception | Legitimate |
| Using the father's surname (RA 9255) | The father acknowledges the child, whether or not the parents marry | Still illegitimate |
| Adoption | Legitimation is not possible, for example where a spouse wants to adopt a partner's child | Legitimate child of the adopter |
If the child was registered under the father's surname even though the parents were not married, the birth record may need correcting after legitimation. Ask the civil registrar; see correcting a PSA certificate.
Documents to Attach to the Affidavit
From the PSA rules for RA 9858. The civil registrar may ask for more and will tell you its fees.
Your ticks stay on this device only.
Common Questions
We Married After Our Child Was Born. Is Our Child Automatically Legitimate?
The marriage is what makes the child legitimate, if nothing stopped you from marrying when the child was conceived. But the civil registry will not show it until you sign and register a Joint Affidavit of Legitimation, so a note can be added to the birth record.
The Father Was Married to Someone Else When Our Child Was Born. Can Our Child Be Legitimated Now That We Are Married?
No. The law looks at whether the parents could have married each other at the time of conception. An earlier marriage was a legal reason you could not marry then (an impediment), so the child cannot be legitimated by the later marriage. The child can still use the father's surname if he acknowledges them.
We Were Both 17 When Our Child Was Conceived. Can Our Child Be Legitimated?
Yes. RA 9858 (2009) allows legitimation where the only thing stopping the marriage was that one or both parents were below 18.
Where Do We File the Affidavit?
With the local civil registry office of the place where the child was born, within 30 days of signing it. For a child born abroad, the PSA rules point to the Office of the City Civil Registrar of Manila.
Is Legitimation the Same as Using the Father's Surname Under RA 9255?
No. RA 9255 lets an illegitimate child use the father's surname, but the child stays illegitimate. Legitimation makes the child legitimate, with the same rights as a legitimate child.
Not legal advice. This is general information. For advice on your own situation, consult a lawyer. If you cannot afford one, the Public Attorney's Office (PAO) or an IBP legal aid office may help for free.
Government fees, rules and requirements change, so always check with the office concerned before you go. Last reviewed October 8, 2026.