Short answer. One-fourth of the hereditary estate. Article 892 of the Civil Code entitles the surviving spouse to that fourth whenever only one legitimate child or descendant survives. It is taken from the portion the deceased could freely dispose of, not from the child's own legitime, so the child's share is not reduced to fund it.
What the law says
If only one legitimate child or descendant of the deceased survives, the widow or widower shall be entitled to one-fourth of the hereditary estate.
Civil Code, Article 892 — Legitime Of Surviving Spouse. Read the full provision →
The one-fourth rule for a single child
Article 892 is direct on this exact composition: if only one legitimate child or descendant of the deceased survives, the widow or widower shall be entitled to one-fourth of the hereditary estate. This applies specifically where there is exactly one legitimate child or descendant standing to inherit alongside the spouse. The one-fourth figure is fixed by the article itself; it is not a starting point for negotiation among the heirs, and it does not depend on the size of the estate.
Where the spouse's fourth actually comes from
Article 892 also settles a question that often causes confusion: whose share absorbs the spouse's portion. It states plainly that the legitime of the surviving spouse shall be taken from the portion that can be freely disposed of by the testator. In other words, the spouse's one-fourth is carved out of the free portion the deceased could have willed to anyone, not out of the child's own legitime. The child's entitlement as sole legitimate heir is not diminished to make room for the spouse's share.
How this changes with more children
The one-fourth figure applies only to the single-child scenario. Article 892 says that if there are two or more legitimate children or descendants, the surviving spouse shall be entitled to a portion equal to the legitime of each of the legitimate children or descendants instead — a different measure tied to however many children there are, rather than a flat fraction of the estate. If your family situation involves more than one legitimate child, this one-fourth answer does not carry over.
A fact-dependent exception worth knowing
Article 892 also addresses legal separation: in case of a legal separation, the surviving spouse may inherit if it was the deceased who had given cause for the same. That means a spouse's right to inherit at all can turn on who was at fault in a legal separation, which the article itself makes fact-specific rather than automatic. If a legal separation is part of your family's history, that detail needs to be worked through before assuming the one-fourth share applies.
Cases citing this provision
These Supreme Court decisions cite the provision above. We list them so you can read them yourself; the summaries of what each decided are not ours to give.
- Elenita V. Macalinao, Kenneth V. Macalinao and Kristel V. Macalinao vs. Cerina, A.K.A. Cerena N. Macalinao and Cindy N. Ma, G.R. No. 250613, April 3, 2024 — read the decision on LawPhil →