Short answer. No. Under Article 873 of the Civil Code, impossible conditions in a will are considered as not imposed and do not prejudice the heir. The condition is simply disregarded — you inherit as if it were never written, and the testator cannot override this rule even by expressly providing otherwise.
What the law says
Impossible conditions and those contrary to law or good customs shall be considered as not imposed and shall in no manner prejudice the heir, even if the testator should otherwise provide.
Civil Code, Article 873 — Impossible and Unlawful Conditions. Read the full provision →
What the Civil Code says about impossible conditions in a will
Article 873 draws a firm line: when a testator attaches an impossible condition to an inheritance, the law treats that condition as not imposed at all. The inheritance does not fail because the condition cannot be met. Instead, the condition is stripped from the will and the heir takes the bequest unconditionally. The same rule applies to conditions that are contrary to law or to good customs — they, too, are simply disregarded. Crucially, the article closes off the testator's ability to reverse this: even if the testator should otherwise provide, the condition still cannot prejudice the heir.
What makes a condition 'impossible'
A condition is impossible when it cannot be fulfilled by any human being under normal physical or legal circumstances — walking across the country barefoot, reaching the moon on foot, or producing a document that no longer exists. The impossibility must be objective, not merely difficult. A condition that is merely burdensome or hard to satisfy is not impossible in the legal sense; the heir would need to comply. The test is whether the thing demanded is, in the nature of things, incapable of being done.
Conditions contrary to law or good customs are treated the same way
Article 873 groups impossible conditions together with two other categories: conditions that violate the law, and conditions that violate good customs. A testator cannot effectively write, for example, that you inherit only if you commit fraud or abandon your children. Like impossible conditions, these are struck from the will without affecting the gift itself. The heir receives the inheritance free of the tainted condition. This prevents a will from being used as a tool for coercion or as an instrument for illegal purposes.
The condition is removed — the inheritance is not
The important practical point is that Article 873 does not void the institution of the heir. It voids only the condition. So the question to ask is not whether you can fulfill the condition, but whether the condition is impossible or unlawful. If it is, you are still an heir — just an unconditional one. If you have been told by co-heirs or by the estate administrator that you cannot claim your share because you did not satisfy a condition in the will, it is worth examining whether that condition falls under Article 873.