You must be at least 18 years old to make a will in Washington. The document must be dated and signed by you, per the Washington State Bar Association. You have to be mentally competent and able to understand your will's provisions. If you are improperly influenced or pressured into making your will, the document may be invalidated in court after your death. Section 11.12.020 of the Revised Code of Washington permits another person to sign the will for you if you are unable to do so, but the signing must be at your direction and in your physical presence.
Your will must be signed by two mentally competent witnesses in Washington, but witnesses do not have to read the will or have any knowledge of your provisions. Under Section 11.12.020 of the RCW, a typed will may be accepted by the court without the signatures of the witnesses if accompanied by affidavits from the persons; however, a handwritten will must have the actual signatures of the witnesses. A handwritten will is still valid even if signed by interested witnesses -- persons who benefit under the will -- but using a beneficiary as a witness may be viewed as a conflict of interest after your death. A will with both handwritten and typed sections may be treated as an entirely handwritten will, depending on what sections are handwritten and the court's decision on the matter.
A will has to clearly provide for disposal of your property in Washington. You may name any person, business, charity or other organization as a beneficiary under your will, but the recipients must be identified by name or relation to you. If your handwriting is not legible in any provisions of the will, the court may decide your intentions during probate, the legal proceeding used to validate your will and settle your estate.
Foreign Will Exception
A handwritten will that is not witnessed may be valid in Washington if you made the will while you were a resident of a different state where such wills are valid. However, the will must meet all other requirements as set forth under the laws of the state where the document was executed.