Short answer. Only if you hold something back for support. The Civil Code lets a donation cover all your present property, but only if you reserve - in full ownership or in usufruct - enough to support yourself and those the law says you must support. Without that reservation, the donation can be reduced on the petition of anyone affected.
What the law says
The donation may comprehend all the present property of the donor, or part thereof, provided he reserves, in full ownership or in usufruct, sufficient means for the support of himself, and of all relatives who, at the time of the acceptance of the donation, are by law entitled to be supported by the donor.
Civil Code, Article 750 — Giving Away Everything You Own. Read the full provision →
You can give a lot — but not leave yourself with nothing
The law does not forbid sweeping generosity, but it refuses to let you strip yourself bare. The article allows that the donation may comprehend all the present property of the donor, or part thereof, provided he reserves, in full ownership or in usufruct, sufficient means for the support of himself, and of all relatives who, at the time of the acceptance of the donation, are by law entitled to be supported by the donor. So you may give away your present property, even the whole of it in scope, on one firm condition: you must keep back enough to support yourself and those you are legally obliged to support. The reservation is the price of giving so freely.
What the reservation must cover
Two groups are protected by the required reservation: you, the donor, and the relatives who, by law, are entitled to be supported by you. Support in this sense is the maintenance the law obliges certain family members to receive, and the people entitled to it are fixed at the time the donation is accepted. The reservation can take one of two forms — you may hold back property in full ownership, or keep a usufruct over it, meaning the right to its use and fruits. Either way, what you retain must be sufficient for that support. The aim is to ensure that neither you nor your dependents are left destitute by your own gift.
The consequence of not reserving enough
If you ignore the condition, the donation is not simply upheld as you made it. The article states that without such reservation, the donation shall be reduced in petition of any person affected. That means a gift which fails to leave enough for the required support can be cut down — reduced to the extent necessary — at the instance of a person affected by the shortfall, such as a dependent deprived of their support. The donation is not automatically void in whole; rather, it is vulnerable to being trimmed so that the protected support is restored. This keeps the door open to generosity while guarding those the law will not let you abandon.
Present property, and a word of caution
Note that the article speaks of present property — what you own at the time — and donations of what you might acquire in the future are treated differently under the law. Giving away everything you presently own is a serious step with lasting effects: it is generally meant to be irrevocable, it can affect your dependents, and lifetime transfers can later interact with the rules protecting the shares reserved for compulsory heirs when your estate is settled. Because the reservation for support and these other limits are easy to get wrong, anyone contemplating a donation of all or most of their property should have it structured and documented with a lawyer beforehand.