A codicil in estate planning refers to a legal document that is used to make specific changes, additions, or amendments to an existing will. Instead of creating an entirely new will, a codicil allows individuals to modify certain provisions of their will while keeping the rest of the document intact. This can be useful when relatively minor changes are needed in the estate plan.

Here are some key points about codicils:

1. Amendments to Wills: A codicil is essentially an addendum to a will. It allows the testator (the person making the will) to make changes without needing to rewrite the entire will.
2. Formal Legal Document: Like a will, a codicil must meet certain legal requirements to be valid. These requirements can vary by jurisdiction but often include signatures from witnesses and compliance with the laws governing wills.
3. Content Changes: A codicil can be used to alter specific clauses in a will, such as changing the distribution of assets, updating the appointment of an executor, or revising provisions related to guardianship of minor children.
4. Revocation and Superseding: If a codicil contradicts a provision in the original will, the provisions of the codicil usually take precedence. It's also possible to revoke a codicil by creating a new codicil or a new will that explicitly revokes the previous documents.
5. Proper Execution: To ensure the legality of the codicil, it's important to follow the legal requirements for its execution. This often includes having the document signed by the testator and witnessed by individuals who are not beneficiaries of the will.
6. Consideration of Full Will Review: While codicils can be useful for making minor changes, if significant alterations are needed or if there are multiple changes over time, it might be more practical to create a new will that incorporates all the desired updates. This can help avoid confusion and potential conflicts.