|Part of the common law series|
|Other common law areas|
A codicil is a document that amends, rather than replaces, a previously executed will. Amendments made by a codicil may add or revoke small provisions (e.g., changing executors), or may completely change the majority, or all, of the gifts under the will. Each codicil must conform to the same legal requirements as the original will, such as the signatures of the testator and, typically, two or three (depending on the jurisdiction) disinterested witnesses.
When confronted with testamentary writings executed after the date of the original will, a probate court may need to decipher whether the document is a codicil or a new will. As a rule of thumb, if the second document neither expressly revokes the prior will in its entirety nor supersedes it for all purposes by making a complete disposition of the testator’s property, it will be presumed to be a codicil, leaving the validity of the earlier will unchanged with respect to the property whose disposition the codicil does not address.
In some jurisdictions, acting as a witness to the execution of the codicil may invalidate a gift to a beneficiary under the original will. This rule extends such a jurisdiction's "disinterested-witnesses" requirement to those subsequent documents that might affect what a beneficiary receives from the probate process. For example, if a codicil revokes a bequest in a prior will or adds one not in the prior will, it thereby increases or decreases the value of the residuum of the estate, and it thereby affects any residuary beneficiaries' interest in the estate, such that a residuary beneficiary in a will is an interested party with respect to any codicil.
As an alternative to a codicil, a testator may modify an existing will by writing a new, dated will which revokes any previous wills and codicils. With the advent of word-processors this is now becoming recommended practice (as suggested by the international specialist body in this field, the Society of Trust and Estate Practitioners) even for relatively minor changes to avoid the difficulties of interpretation which can arise from a chain of (possibly mutually inconsistent) codicils. Particular difficulties in interpreting chains of codicils arise in jurisdictions such as England and Wales which do not require wills or codicils to be dated (although this is common practice).
In completion of a codicil, a form must be created specifying the modifications to the existing last will and testament. As with a last will and testament, it is necessary to witness amendments to the will since they may override the relevant sections of the original will.
According to the Merriam Webster dictionary the definition of codicil is: "A legal instrument made to modify an earlier will." 
- Dukeminier & Johanson (2005, Apr 29) Wills, trusts, and estates, Aspen Publishers, Inc.; 7th edition (April 29, 2005)
- Sample last will codicil (United States)
|This legal term article is a stub. You can help Wikipedia by expanding it.|