Short answer. No. Article 900 of the Civil Code reduces the surviving spouse's legitime to one-third in this situation. A deathbed marriage where the testator dies within three months and the couple had not lived together for more than five years triggers the reduced share — not the standard one-half.
What the law says
If the marriage between the surviving spouse and the testator was solemnized in articulo mortis, and the testator died within three months from the time of the marriage, the legitime of the surviving spouse as the sole heir shall be one-third of the hereditary estate, except when they have been living as husband and wife for more than five years.
Civil Code, Article 900 — Legitime Of Sole Surviving Spouse. Read the full provision →
The standard rule and the exception for deathbed marriages
Under Article 900, the normal legitime of a sole surviving spouse is one-half of the hereditary estate. But the article carves out a specific situation that triggers a reduced share. When the marriage was solemnised in articulo mortis — at the point of death — and the testator died within three months, the surviving spouse's legitime as sole heir is one-third rather than one-half. Your father's situation meets both conditions: a deathbed marriage and death within three months. Unless the cohabitation exceeded five years, the one-third applies.
Why the law reduces the share in this situation
The reduction reflects a concern about late-stage marriages entered into primarily to secure inheritance rights for someone with little genuine connection to the deceased or his family. A marriage solemnised at the point of death, when the deceased is already incapacitated or near the end, may not reflect a longstanding commitment. The Civil Code therefore protects the other heirs by limiting what the newly married survivor can claim. It is not a penalty on the marriage itself — the marriage is valid — but a limitation on how much of the estate can be diverted to the new spouse.
The five-year cohabitation exception does not apply here
Article 900 provides one escape from the reduced share: the couple must have been living as husband and wife for more than five years before the marriage. If that exception applied, the surviving spouse would revert to the full one-half. But in the situation you describe — less than five years of cohabitation — the exception is unavailable. The widow's claim is limited to one-third. The remaining two-thirds is available for distribution to the other heirs according to the will or the intestate succession rules.
What this means for the estate and the other heirs
If the widow is the sole heir — meaning no children or other compulsory heirs survive — she gets one-third and the testator could freely dispose of the remaining two-thirds by will. If there are other compulsory heirs, such as children, the computation becomes more complex: the legitimes of all compulsory heirs must be satisfied from the estate, and the widow's one-third share must be worked into that calculation. Disputes over whether the cohabitation actually exceeded five years are common in these situations. A lawyer can help you assess the evidence of cohabitation duration and advise on whether the widow's claim to a larger share has any factual basis.