Codicil to a Will: What It Is and When to Challenge One

What a Codicil Does

A codicil is a legal amendment to an existing will. Rather than drafting an entirely new will, the testator adds a codicil to change specific provisions — updating a beneficiary, modifying a bequest, replacing an executor, or revoking particular clauses while leaving the rest of the will intact.

Multiple codicils can amend a single will. The original will and all valid codicils together form the complete testamentary plan.

Legal Requirements for a Valid Codicil

A codicil must meet the same execution requirements as the will itself. In most jurisdictions, that means:

• It must be in writing
• The testator must sign it (or direct someone to sign on their behalf in their presence)
• At least two competent witnesses must observe the signing and sign the document themselves
• The testator must have testamentary capacity at the moment of execution

These requirements exist because codicils are often executed late in life — sometimes in hospital rooms, care facilities, or private homes — when the testator may be physically or mentally vulnerable. A codicil that doesn't meet the formal execution requirements is invalid, regardless of what it says.

Why Codicils Draw Challenges

Codicils are disproportionately targeted in estate disputes for several reasons.

Timing. A codicil executed weeks or days before death, especially one that dramatically changes who inherits, raises immediate questions about whether the testator was acting freely and with full understanding.

Setting. Hospital-bed codicils and documents signed in care homes, where the testator was under the direct care and influence of certain individuals, invite scrutiny about undue influence.

Interested witnesses. Under traditional common law, a gift to someone who also served as a witness to that codicil can be automatically voided. Some US states have abolished this rule, but using a beneficiary as a witness still invites challenge.

Contradictions. When a codicil conflicts with earlier estate planning — decades of consistent documents suddenly reversed by a brief amendment — courts and family members ask why.

Grounds for Challenging a Codicil

The same legal grounds that apply to contesting a full will apply to a codicil:

Lack of capacity. The testator must have met the four-part Banks v. Goodfellow test at the moment they signed the codicil. If they had advanced dementia or were heavily medicated, the codicil's validity depends on whether they experienced a "lucid interval" at the time of execution.

Undue influence. If the person who benefits most from the codicil also controlled the testator's daily life, finances, or access to other family members, courts will scrutinize whether the amendment reflected the testator's genuine wishes.

Fraud. Someone misrepresenting what the document contained, lying about a family member's circumstances, or tricking the testator into signing something they didn't understand.

Defective execution. Missing witnesses, unsigned pages, or failure to follow the jurisdiction's formal requirements.

Codicil vs. New Will

Modern estate planning generally favors drafting a new will rather than adding codicils. A new will typically includes a clause revoking all prior wills and codicils, which eliminates confusion about which provisions control.

Codicils made sense when wills were typewritten and re-drafting was expensive. Today, with word processing and digital storage, creating a clean updated will is usually simpler and less vulnerable to challenge.

That said, codicils remain common when the change is minor — swapping one executor for another, for example — and the testator's attorney sees no reason to re-execute the entire document.

What to Do If a Suspicious Codicil Surfaces

Start by comparing the codicil against the original will and any prior codicils. Note what changed, when it was signed, who witnessed it, and who benefits from the alteration.

Gather the testator's medical records from around the date of execution. If they were in a care facility, request visitor logs and medication records. These documents establish the testator's cognitive state and who had access to them during the relevant period.

Our Contesting a Will toolkit includes a document audit checklist that walks through each element of a codicil review, from witness verification to capacity evidence collection.