Short answer. Philippine law recognizes four types of substitution of heirs under Article 858: simple or common, brief or compendious, reciprocal, and fideicommissary. Each type serves a different purpose and carries its own set of rules governing how and when the substitute actually receives the inheritance.
What the law says
Substitution of heirs may be: (1) Simple or common; (2) Brief or compendious; (3) Reciprocal; or (4) Fideicommissary.
Civil Code, Article 858 — The Four Kinds of Substitution. Read the full provision →
Why name a substitute heir at all
A testator names a substitute heir to guard against the possibility that the first-designated heir cannot or will not inherit — because the heir dies before the testator, refuses the inheritance, or is declared incapacitated. Without a substitute, the share would fall into intestacy and be distributed according to the default rules of the Civil Code, regardless of what the testator intended. Naming a substitute keeps the testator's wishes intact even when the primary heir drops out.
Simple or common substitution
Simple or common substitution is the most straightforward: if the first heir does not inherit — whether because of predecease, incapacity, or refusal — the named substitute steps in and takes the same share. The testator can name one substitute or several. If several substitutes are named without specifying shares, they divide the inheritance equally among themselves. This is the type most wills contemplate when they say something like 'if my son does not survive me, his share goes to my daughter.'
Brief or compendious substitution
Brief substitution names one substitute for several heirs at once. Compendious substitution names several substitutes for a single heir. Both are recognized variants that compress what would otherwise require multiple separate clauses into a single directive in the will. They follow the same basic principle as simple substitution — the named substitute or substitutes inherit only if the primary heir or heirs cannot or do not.
Reciprocal substitution
Reciprocal substitution arises when co-heirs are made substitutes for one another. For example, a testator may leave property to three children and provide that if any of them fails to inherit, the surviving ones share that portion equally. The substitution runs between the primary heirs themselves. If the share cannot be determined without knowing which of them survives, the will should specify how the reciprocal arrangement works to avoid ambiguity.
Fideicommissary substitution
Fideicommissary substitution is fundamentally different: the first heir — the fiduciary — actually receives and holds the property, but is obligated to deliver it to a second heir — the fideicommissary — upon the occurrence of a specified event, usually the fiduciary's death. This is not a fallback arrangement; it is a staged transfer. The Civil Code imposes strict limits: the fideicommissary must be at most one degree removed from the fiduciary in the line of succession, ensuring that the property passes cleanly within one generation.