Short answer. Yes, in a specific legal sense. Article 836 says the execution of a codicil referring to a previous will has the effect of republishing the will as modified by the codicil. Making a valid codicil does not just add to the will; it republishes it, treating the will as re-executed on the codicil's date, as changed.
What the law says
The execution of a codicil referring to a previous will has the effect of republishing the will as modified by the codicil.
Civil Code, Article 836 — Republishing by Codicil. Read the full provision →
What republishing a will means
A codicil is a separate testamentary document that adds to or changes an existing will. Article 836 explains its effect: the execution of a codicil referring to a previous will has the effect of republishing the will as modified by the codicil. 'Republishing' means the will is treated as if made again, re-affirmed and re-dated, as of the time the codicil is executed, incorporating the codicil's changes. So a codicil does more than tack on an amendment; it revives the whole will and gives it fresh life as of the codicil's date, with the alterations built in. The will and codicil are then read together as one testamentary plan.
Why the republication date can matter
Because republication moves the effective date of the will forward to the codicil, it can carry practical consequences. A will that had a doubtful earlier execution can be reaffirmed. Changes in circumstances between the two dates, such as property acquired or relationships changed, are read against the later, republished date rather than the original one, which can affect how the will is interpreted. In some situations a codicil can even breathe validity into a will that had been revoked, if the codicil clearly refers to and adopts it. The dating effect is not a technicality; it can change what the will is understood to dispose of and in whose favor.
What a codicil does not do
Republishing is not the same as rewriting from scratch, and a codicil has limits. It must itself be executed with the same formalities the law requires of a will; a note scribbled and unsigned, or lacking the required witnesses, is not a valid codicil and republishes nothing. It changes only what it addresses, and the parts of the will it does not touch stand as before, now read as of the new date. And a codicil that does not refer to a previous will does not republish one. If your goal is a wholesale change, a new will that revokes the old may be cleaner than layering codicils.
Using codicils carefully
For someone updating their estate plan, Article 836 is reassuring: a properly made codicil genuinely updates and reaffirms the will rather than creating a confusing rival document. But the safeguard is in the execution. Keep the codicil and the will together, make sure the codicil clearly identifies the will it modifies, and observe the same formalities you observed for the will itself. Where the changes are extensive or the old will is itself doubtful, republishing a flawed instrument may simply carry the flaw forward. Reviewing whether to amend by codicil or to make a fresh will is worth doing before you sign either.