A joint will is a single will made by spouses that disposes of each spouse's property. Like any other will, it must meet state law requirements in order to be legal. As of 2010, a joint will does not have to be notarized to be legal in any state except Louisiana.
A joint will is a single will document. Unlike most wills, however, a joint will gives instructions for what to do with the property of two different people, usually spouses. Most joint wills state that each spouse's property should be left to the other spouse, and the will usually gives instructions for distributing the property after both spouses are gone. A mutual will is similar to a joint will, except that it can be made among more than two parties.
Signing a Joint Will
Like a will for an individual person, a joint will must be signed by the testators, or the persons who made the will. Since a joint will is usually made by spouses, both spouses must sign the will. Each spouse should also put the date beside his or her signature. A simple clerical error, like signing on the signature line reserved for the other spouse, will not invalidate a joint will as long as the will meets the other requirements of state law, according to "Wills, Trusts and Estates."
Witnesses for Joint Wills
Since a joint will is a single will, it only requires the number of witnesses required for a single will in the state where it is made, according to the American Bar Association. Most states require two witnesses to make a valid will; Vermont requires three witnesses, while Louisiana requires only one witness. The witnesses should watch the testators sign the joint will and then should sign to indicate they watched the testators sign their will.
Louisiana is the only state that requires a will to be notarized in order to be valid. Under the Louisiana Probate Code, the will must be notarized and signed by at least one witness. However, many states allow testators to use a notary to make the will "self-proving," which allows it to go through probate without requiring the witnesses to testify that they did in fact witness the testator's signing of the will, according to FindLaw.