Short answer. The newest ones are reduced first. When donations exceed what the donor could legally give away, the Civil Code directs that the most recent donations are suppressed or reduced before older ones are touched. The oldest donations are the last to be cut.
What the law says
those of the more recent date shall be suppressed or reduced with regard to the excess
Civil Code, Article 773 — Which Donations Are Cut First. Read the full provision →
The rule: newer donations are cut first
Article 773 of the Civil Code answers this question directly: If, there being two or more donations, the disposable portion is not sufficient to cover all of them, those of the more recent date shall be suppressed or reduced with regard to the excess. The rule works chronologically in reverse — starting with the most recent donation and moving backwards until the excess has been absorbed. The older a donation is, the more protected it is. An early donee keeps their gift intact for as long as there are later donations that can absorb the reduction.
Why the law protects earlier donations
The policy behind this rule is that a donor's earlier choices should prevail over later ones when there is not enough room in the estate for all of them. When your father made his first donation, that donee received a promise the law now honors. Later donees accepted their gifts knowing, at least in principle, that the donor's estate might already be partly committed. Later gifts are treated as less firmly established than earlier ones — the most recent donee is the first to absorb the shortfall, not the first donee who may have been relying on the gift for years.
What suppression and reduction mean in practice
The statute uses two terms: suppressed and reduced. A donation is suppressed when the entire gift must be returned because it is wholly inofficious — it exceeds what the donor could give. A donation is reduced when only part of it must be given back, because only a portion overshoots the limit. The most recently made donation is dealt with first. If eliminating it entirely still does not close the gap, the next most recent donation is taken up, and so on, until the excess has been fully absorbed. Earlier donations are only touched if the newer ones are not enough.
What you should do
If you believe your father's donations exceeded what he could legally give — typically because they impaired the legitime of compulsory heirs — the proper step is to have the donations valued and dated, then compute how much of the total exceeded the disposable portion. The most recently dated donation is reduced first. If it can absorb the entire excess, the earlier donees keep everything. If not, the next donation in reverse order is addressed. Establishing exact dates and valuations is critical to working out who must give back what, and by how much.