Short answer. Yes. Article 144 of the Family Code says separation of property may refer to present or future property or both, and may be total or partial. You can limit your agreement to future property alone, but whatever you leave out stays under the absolute community.
What the law says
Separation of property may refer to present or future property or both.
Family Code, Article 144 — Separation May Be Total or Partial, Present or Future. Read the full provision →
What the law says
It may be total or partial. In the latter case, the property not agreed upon as separate shall pertain to the absolute community.
Family Code, Article 144 — Separation May Be Total or Partial, Present or Future. Read the full provision →
Present, future, or both — your choice
Article 144 gives spouses flexibility over what a separation of property agreement actually covers. Separation of property may refer to present or future property or both. Nothing in the article requires the agreement to address everything at once — limiting it to property you will acquire in the future, and leaving out what you already own, is one of the combinations the article expressly allows, without needing to justify why the present property was excluded.
Partial separation is its own recognized category
Article 144 also confirms that separation need not be all-or-nothing: It may be total or partial. An agreement covering only future property, and not present property, is a form of partial separation, which the article treats as valid alongside full separation covering everything you own or will own. The two lines the article draws — present versus future, and total versus partial — can be combined in whatever way fits what you and your spouse actually intend.
What happens to the property you leave out
The article completes the picture with what a partial agreement means for everything not addressed: In the latter case, the property not agreed upon as separate shall pertain to the absolute community. If you separate only future property, your present property is not left in limbo — it falls under the absolute community by default, unless some other applicable rule says otherwise, and it is administered and disposed of under the ordinary rules that govern that community.
Why this matters for drafting your agreement
Since Article 144 treats a future-only agreement as valid, you can structure your separation agreement narrowly on purpose. But because whatever is left out defaults to the absolute community, it is worth being explicit about which property the agreement covers, so there is no confusion later about whether a particular asset was meant to be separated or was simply never addressed. A clearly worded agreement that names present property as remaining part of the absolute community, while listing what future property is being separated, leaves less room for that kind of dispute.