Short answer. Yes. Executing a codicil that refers to a previous will republishes that will as modified by the codicil. The two are read together as one current instrument, and the will is treated as re-made at the date of the codicil, carrying forward everything the codicil does not change.
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 →
The codicil republishes the will
Article 836 gives a codicil a reach beyond its own words: the execution of a codicil referring to a previous will has the effect of republishing the will as modified by the codicil. A codicil is a supplement, an instrument that adds to or alters an existing will without replacing it. When it refers to that earlier will, the law does not treat the two as separate scraps but as a single, current disposition: the original will, brought forward and read together with the changes the codicil introduces. What the codicil leaves alone continues in force exactly as the will provided.
The will is treated as re-made
The practical effect of republication is that the will speaks anew as of the date of the codicil. It is as though the testator sat down on that later date and re-affirmed his will as amended. This can matter: a disposition that might have been read against the state of the testator's family or property at the original date is now read as of the codicil's date, and property or circumstances that changed in between are viewed through that fresher moment. The codicil does not merely tack on a clause; it refreshes the whole instrument's date of effect.
What republication cannot do
There is a boundary. Republication carries forward a will that was validly made; it works because there is a genuine will to bring back. It cannot rescue a will that was void as to its form, one whose execution was defective from the start. That kind of will has to have its dispositions reproduced in a valid instrument, not merely referred to. So a codicil republishes and updates a properly executed will; it is not a shortcut for validating one that never met the formal requirements in the first place.
Execute the codicil properly
Because the codicil is what carries the will forward, the codicil itself must be executed with the same formalities a will requires, the writing, the signing, the witnesses and attestation. A defective codicil cannot republish anything. So if you mean to revise your will by codicil, make sure the codicil clearly refers to the will it is amending, states the changes precisely, and is executed as formally as the will was. Done properly, you end up with one coherent testamentary plan bearing the codicil's date; done carelessly, you risk leaving both instruments in doubt.