All 50 U.S. states require a will to be signed by at least two witnesses, according to MedLawPlus. In most states, anyone who is mentally competent, able to sign his name, and 18 years of age or older may serve as a witness, according to FindLaw. Some states, such as Louisiana, have specific rules about what witnesses must do if the testator, or will maker, has certain disabilities, such as blindness or an inability to write, according to Louisiana Civil Code 1578-1580.
Having a will notarized is not required in any U.S. state besides Louisiana, and a notary's signature cannot take the place of the requirement that two witnesses sign, according to FindLaw. However, a person who is a notary may also serve as a witness to a testator's signature if she meets the state's requirements for witnesses. The fact that a witness is also a notary, however, has no effect on her ability to witness a will, according to FindLaw.
Louisiana is the only U.S. state that requires a will to be notarized to be valid, according to the Louisiana State Bar Association. In Louisiana, a will must be notarized in addition to being signed by two competent witnesses, according to Louisiana Civil Code 1577. The notary's signature alone will not make up for signatures of witnesses that are missing, according to the Louisiana State Bar Association.
In some states, wills that are not witnessed may still be valid if they meet special requirements for exceptions, according to FindLaw. For instance, some states recognize nuncupative wills, also known as oral wills, or holographic wills, which are wills written entirely in the handwriting of the testator. States that recognize these exceptions will find these wills valid even if these wills do not have a witness' signature, according to FindLaw. Notarization of a nuncupative or holographic will is not necessary for the will to be valid and will not make an invalid will valid.