Codicil: Definition and How It Works in California

By Eric Ridley, attorney, Ridley Law. Updated September 2026.

A codicil is a written amendment to an existing will that adds, changes, or revokes specific provisions without replacing the whole document. California treats a codicil as part of the will, so it has to be signed with the same formalities as a will.

How it works in California

Prob. Code, § 88 says that “will” includes a codicil, so wherever the Probate Code sets a rule for wills, that rule applies to codicils too. Under Prob. Code, § 6110, a codicil has to be in writing, signed by the testator, or by someone else in the testator’s presence and at the testator’s direction, and witnessed by two people who are present at the same time, watch the testator sign or acknowledge the signature, and understand they’re witnessing a will.

A codicil can also be entirely handwritten as a holographic codicil, in which case Prob. Code, § 6111 applies instead: the signature and the material provisions have to be in the testator’s own handwriting, and no witnesses are required.

Because a codicil is legally part of the will, courts read the two documents together to figure out what the testator wanted. If the codicil conflicts with the original will, the codicil controls on that point, since it’s the more recent expression of intent.

Why it matters

For example, a man wants to change who serves as his backup executor after his first choice moves out of state. Rather than rewriting the entire will, he signs a short codicil naming a new backup executor and leaving everything else in the original will untouched, as long as he signs it and has it witnessed the same way he would a new will.

Common mistakes

Writing a codicil informally, such as a note attached to the will, without meeting the signing and witnessing requirements. Losing track of which version of a provision controls when a will has been amended more than once. Attempting a significant restructuring of the estate plan through a codicil when a new will, or a full trust restatement, would be clearer.

Related terms

• Will: the document a codicil amends.
• Testator: the person who signs the will and any codicil to it.
• Holographic Will: the handwritten, unwitnessed format a codicil can also take.
• Trust Amendment: the equivalent document used to change a revocable trust instead of a will.

Part of the California estate planning glossary.