What is a codicil and when should I use one instead of making a new will?

A codicil is a formal document that amends or supplements an existing will without replacing it entirely. It identifies the will it is amending by date, describes the specific change (such as adding a beneficiary, changing the estate trustee, or removing a gift), and must be executed with the same formalities as a will — signed in front of two witnesses who also sign in the testator's presence and in each other's presence.

Codicils work well for narrow, discrete changes where the rest of the will remains sound. Common examples: changing the name of the estate trustee after your first choice has died, adding a gift of a new asset, or updating a beneficiary's share after a family change.

The downsides of codicils are that they add complexity — the codicil and original will must both be tracked, stored together, and submitted to the court together during probate. If you accumulate multiple codicils, the interaction between them can become confusing and create interpretation problems. A codicil also does not allow you to restructure your distribution plan, since it only amends specific provisions.

For any substantial change — a new estate trustee and new beneficiary structure, a changed residue, or updated trust provisions — making a new will that expressly revokes the old one is generally preferable.