What Is a Codicil to a Will and When Do You Need One?

Life changes — and your will should reflect it. When a change is needed, you have two options: rewrite the will entirely, or add a codicil. Understanding when each approach makes sense can save time and prevent complications.

What a Codicil Is

A codicil is a written, signed, witnessed supplement to an existing will. It's a legal document that modifies the original will without replacing it — the two documents are read together, with the codicil controlling where it conflicts with or supplements the original.

Like a will, a codicil must be:

In writing
Signed by the testator (the person whose will it is)
Witnessed by two disinterested witnesses (people who aren't beneficiaries in most states)
Notarized in states that require notarization of wills

A codicil that doesn't meet the same execution requirements as a will in your state may be invalid.

What a Codicil Can Change

A codicil can make virtually any change to a will:

Change the executor
Add, remove, or modify a specific bequest ("I give my piano to [name]" added; an existing bequest removed)
Update a beneficiary's information following a name change or address update
Remove a beneficiary
Change the guardian designation for minor children
Add a residuary beneficiary
Change a bequest from a specific item to a specific dollar amount

Codicil vs. Rewriting the Will: When to Use Each

When a codicil may make sense

The change is simple and isolated — one or two specific modifications
The existing will is recent (drafted within the last 5–10 years) and otherwise accurate
The change is not of a type that would affect how other provisions interact

When rewriting is better

The will is old — outdated references, people or accounts that no longer exist, outdated executor choices
Multiple changes are needed across different parts of the will
You already have one or more codicils (complexity multiplies with each additional document)
The change involves the residuary clause, trust provisions, or other integrated elements that interact with other provisions
Major life changes have occurred since the will was drafted: marriage, divorce, children, death of named beneficiaries

Many estate planning attorneys now recommend simply executing a new will in most situations — it's cleaner, eliminates interpretation complexity, and modern document preparation makes it nearly as fast as drafting a codicil.

What a Codicil Cannot Do

Override a valid beneficiary designation on an account (life insurance, retirement accounts, POD accounts — these pass outside the will)
Change terms of a trust (a trust is a separate document)
Retroactively validate a will that was improperly executed
Revoke or replace a power of attorney or healthcare directive (separate documents)

When to Update Your Estate Planning Documents

Whether through a codicil or a full rewrite, your will should be reviewed after:

Marriage or divorce
Birth or adoption of a child or grandchild
Death of a named beneficiary, executor, or guardian
Significant changes in assets or financial situation
Moving to a different state (different laws may apply)
Major changes in tax law
Every 3–5 years as a general review

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Frequently Asked Questions

What is a codicil and how does it work?

A codicil is a legal supplement or amendment to an existing will. Rather than rewriting the entire will, a codicil adds to, removes from, or changes specific provisions while leaving the rest of the will intact. Like a will itself, a codicil must meet the same formal execution requirements: it must be in writing, signed by the testator, and typically witnessed by two disinterested witnesses (people who are not beneficiaries), with notarization in some states. Once properly executed, a codicil becomes part of the will — it's filed with the will at probate and interpreted together with the original document. Multiple codicils can be added to a will over time, though when codicils accumulate, they can make the document complex and harder to interpret clearly.

When should you use a codicil rather than rewriting your will?

A codicil makes most sense for simple, specific changes to an otherwise solid will: changing an executor, adding or removing a specific bequest, updating a beneficiary's address or name after a legal name change. If the change is straightforward and the existing will is recent and well-drafted, a codicil can be a faster and less expensive approach. However, many estate planning attorneys recommend simply rewriting the will in most cases. Reasons: (1) Rewriting avoids the interpretation complexity that can arise when a will and one or more codicils must be read together; (2) It eliminates the risk of contradictions between documents; (3) Modern will-drafting software makes rewriting almost as fast as writing a codicil; (4) If your will is older, a rewrite is an opportunity to update the entire document with current law and personal circumstances.

Can you write a codicil yourself or does it require a lawyer?

Technically, you can write a codicil yourself — the same as you can technically write a will yourself. The legal requirements are the same: written document, signed by the testator in front of two witnesses, notarized in states that require it. In some states, a handwritten (holographic) codicil signed and dated in your own handwriting may be valid without witnesses. However, a self-drafted codicil carries the same risks as a self-drafted will: improper execution (insufficient witnesses, wrong language, failure to clearly identify what's being changed) can cause the codicil to fail, or create ambiguity that leads to disputes or litigation. For anything beyond the most trivial change, consulting an estate planning attorney is worth the cost.