Short answer. An undated holographic will is not valid under Philippine law. Article 810 of the Civil Code requires that a holographic will be entirely written, dated, and signed by the testator's own hand. All three elements are mandatory — a missing date makes the will void.
What the law says
A person may execute a holographic will which must be entirely written, dated, and signed by the hand of the testator himself.
Civil Code, Article 810 — Holographic Wills. Read the full provision →
All three requirements are mandatory, not optional
Article 810 allows a person to make a will with no witnesses and no notary — but only if the document is entirely handwritten, dated, and signed by the testator. These three elements are stated as requirements, not preferences. A typewritten will cannot become holographic even if the testator signs it. Conversely, a fully handwritten and signed will that carries no date fails the same test. Your mother's will, as written, does not meet the statutory requirements.
Why the date requirement exists
The date serves real purposes in probate. It establishes when your mother had testamentary capacity and allows the court to determine which of two wills is later if she made more than one. It also anchors the will in time to check whether it was revoked or altered before or after certain events. Because the holographic will requires no witnesses — a significant concession — the law compensates by demanding that the document itself carry clear markers of authenticity, including when it was written.
Is there anything that can be done now?
If your mother is still living, the simplest fix is to have her write a new will — properly dated — or to execute a notarial will with the required formalities. A holographic will does not require a lawyer or witnesses; she simply needs to write the entire text again in her own hand, include the date, and sign it. If she has already passed and the undated will is the only document she left, the estate will be treated as though she died without a will, and intestate succession rules will govern who inherits.
The advantage the law gives in exchange for strict formality
The holographic will is, in other respects, the most flexible form of will in Philippine law. It need not be witnessed, can be made inside or outside the Philippines, and is subject to no other formal requirements beyond the three elements listed in Article 810. No notary, no two-witness rule, no specific paper or envelope. That simplicity is precisely why the law holds strictly to what it does require: if date, handwriting, and signature were not all mandatory, the will could too easily be forged or its authenticity disputed.