A codicil is a document that's added to an existing, signed will, to make minor or simple changes to the will. Codicils must be signed and witnessed, just like wills. Now that most wills are created electronically, it's often easier—and clearer—just to make a new will.
Most of us will eventually want to change the first will we make. After all, circumstances change: we marry, divorce, have children, have spats with our relatives, take up and abandon charitable causes. One "last will" isn't likely to carry us through to the end. (See these common reasons to update your estate plan.)
In the past, codicils were used to make very simple changes to wills. For example, if you wanted to change the executor you named, you might create a codicil to a will. But that codicil would still need to be signed and witnessed (see below), just like a new will. And you would always be better off just making a new will in situations like this:
Here's an example of what a codicil to a will might look like:
Of course, a codicil will look different depending on whether it is revising a provision of the will, deleting a provision, or adding one. The codicil must be signed by the will maker and also witnessed by two adults (more on this below).
The past advantages of a codicil are no longer advantages because, these days, it's very easy to use computers to prepare, modify, and print documents. Furthermore, the codicil still needs to be witnessed, just like an entirely new will.
When legal documents were painstakingly written out with quill pens, it made sense not to rewrite a whole will if you could just tack on a brief codicil. But these days, there's no real advantage to a codicil.
There is, however, a drawback: A codicil is unlikely to seamlessly fit with the original will. Is it a pure addition, or does it also negate something in the original document? If it's supposed to replace part of the first will, which part? A codicil can introduce uncertainties. The solution is simple: Just make another will.
Wills, unlike most other legal documents, aren't valid unless they are signed in front of two adult witnesses. Some states require that the witness are "disinterested," meaning that they are not receiving property under the terms of the will. Even if your state doesn't require this, it's usually best practice.
The witnesses aren't there just to make sure you're who you say you are. They sign their own statement at the end of your will, declaring that you seemed of sound mind and not under undue influence—in other words, that it looked to them like you understood what you were signing and were acting of your own free will. (Learn more about the legal requirements of wills.)
This witness requirement for wills isn't likely to go away anytime soon. Wills are simply different from other legal documents because if there's a dispute over the document, the key person—the one who signed it—won't be around to explain what he or she meant. By contrast, if people are arguing about, say, a contract, both of them can go into court and do their best to convince a judge or jury of their point of view.
A few states are chipping away at the witness requirement, by allowing people to sign in front of a notary public instead of witnesses, but it's definitely the exception to the rule. After all, a notary public checks your driver's license and verifies your identity, but isn't asked to form any opinion about your mental state.
So what makes a codicil legal? Because they are just like wills, witnesses are required for them, too. So if, after you make and sign your will, you want to add a new paragraph with a codicil, you'll have to sign the codicil in front of two witnesses, just like the original will. You can't simply write your change on a piece of paper and leave it at that; it won't be legally valid.
These days, it's easy to start from scratch, using reputable software or an online service like Nolo's Quicken WillMaker. (WillMaker also saves your original will so that it's easy to edit and print.)
Or start with your original will, which is surely on a computer somewhere—in your home or office, if you prepared it yourself, or perhaps in your lawyer's office if you hired someone to prepare it. If you can't get your hands on the file, just retype it—carefully. Make the changes you want. And then get two witnesses to watch you sign.
Or, if you have a more complicated situation, consult an estate planning attorney.