Short answer. No. Disinheritance in the Philippines works only on grounds expressly listed in the law. A parent cannot simply write a personal reason into the will and expect it to hold — if the stated ground is not one of the causes the Civil Code recognizes, the disinheritance is void.
What the law says
A compulsory heir may, in consequence of disinheritance, be deprived of his legitime, for causes expressly stated by law.
Civil Code, Article 915 — Disinheritance Defined. Read the full provision →
Why a testator cannot disinherit freely
Philippine succession law protects certain heirs — called compulsory heirs — by guaranteeing them a fixed portion of the estate called the legitime. Children, both legitimate and recognized, are compulsory heirs. Because the law itself reserves this share for them, a testator cannot override it simply by expressing a wish in a will. The only mechanism the law provides for stripping a compulsory heir of their legitime is disinheritance — and even that is tightly controlled. Article 915 makes clear that it works only "for causes expressly stated by law," not for causes the testator invents.
The valid grounds are specific and limited
The Civil Code lists the valid grounds for disinheriting a child in Articles 919 to 921. These include serious wrongs against the testator — such as making false criminal accusations, causing the testator to be convicted of a crime, physical maltreatment, inducing the testator by fraud or violence to change the will, and certain other grave acts. A parent who simply dislikes a child, has a falling out with them, or wants to favor other children over them does not have grounds for disinheritance unless the child's conduct falls within one of those enumerated causes.
Form matters as much as the ground
Even when a valid ground exists, disinheritance must be done properly. The ground must be stated in the will itself — a verbal statement or a separate document is not enough. It must also be true: if the heir being disinherited can prove the stated ground is false, the disinheritance is annulled. The heir does not lose the legitime; they regain it. This combination — an enumerated ground, stated in writing, that is actually true — creates the floor any disinheritance must clear.
What happens to a failed disinheritance
If a will attempts to disinherit a child on grounds not recognized by law, or without proper formality, the disinheritance is simply void. The heir is entitled to their legitime as if the attempt had never been made. The rest of the will remains in effect — the failed disinheritance does not invalidate the entire document. The practical result is that the disowned child can go to court to claim their legal share of the estate, and the court will restore it without regard to the testator's stated wishes.