What is codicil?

A codicil is a supplement to a will, not a substitute for it. When someone wants to make a change to their existing will — updating a beneficiary's name after a marriage or divorce, changing a personal representative, adding a provision for a pet, or accounting for new property — a codicil lets them do so without rewriting the entire will. The codicil identifies the will it modifies (usually by referencing its date) and states that the rest of the original will remains in effect except for the specific changes described.

Because a codicil carries the same legal weight as a will, it must be executed with the same formalities: it generally needs to be signed by the testator (the person whose will it is) and witnessed, typically by two witnesses. Requirements vary by state, and some states allow notarization as an alternative or addition to witnessing. Failing to follow the proper formalities can render a codicil invalid, so many people work with an estate planning attorney when drafting one.

Codicils are best suited to minor, straightforward changes. If someone needs to make several changes, add or remove beneficiaries, or make other substantial revisions, estate planning resources generally recommend revoking the old will and creating a new one instead, since multiple codicils attached to a will can create confusion or even contradictions that are harder for an executor or family members to sort out after death. A codicil should always be stored together with the original will so both documents can be located and read together, since both are submitted for probate.

The word comes from the Latin codicillus, meaning 'little book' or 'small writing tablet,' and the concept traces back to Roman law, where codicils offered a more flexible, less formal way to express testamentary wishes alongside a will.