Short answer. Yes, they are reduced. Article 910 of the Civil Code provides that donations to an illegitimate child are charged to that child's legitime; if they exceed the freely disposable portion, they are reduced. Under current law, an illegitimate child's legitime is one-half of the legitime of a legitimate child.
What the law says
Donations which an illegitimate child may have received during the lifetime of his father or mother, shall be charged to his legitime. Should they exceed the portion that can be freely disposed of, they shall be reduced in the manner prescribed by this Code.
Civil Code, Article 910 — Donations Charged to the Legitime. Read the full provision →
The rule in Article 910
Article 910 of the Civil Code provides a two-step rule for lifetime gifts to an illegitimate child. First, those donations are charged to the child's legitime — they count against what the child is entitled to by law, not against the freely disposable portion. Second, "Should they exceed the portion that can be freely disposed of, they shall be reduced in the manner prescribed by this Code." If the total value of gifts exceeds both the illegitimate child's legitime and the freely disposable portion combined, the excess is subject to reduction to protect the legitimes of other compulsory heirs.
How this article reads today
Article 910 was written when the Civil Code categorized illegitimate children differently. The current rule on the share of an illegitimate child's legitime is set by the Family Code, which provides that the legitime of each illegitimate child is one-half of the legitime of a legitimate child, and that except for this modification, all other provisions of the Civil Code governing successional rights remain in force. Article 910's mechanism — charge donations to the legitime, reduce excess — continues to operate, but the size of the legitime it references is now governed by the Family Code's formula.
How the reduction works
When computing the estate, the donations an illegitimate child received during the father's lifetime are added back to arrive at the notional estate. The illegitimate child's legitime (one-half of a legitimate child's share) is computed on that notional estate. The donations are charged to that legitime first. If the donations exceed the legitime, the excess is applied against the freely disposable portion. Only when the total donations exceed both the legitime and the freely disposable portion does a reduction actually occur — and then only by the amount of the excess, not the whole donation.
Who can demand reduction and when
Reduction of excessive donations is not automatic — it must be sought by the compulsory heirs whose legitimes are impaired. The legitimate heirs, who have a fixed share of the estate, have the most direct stake in insisting that excess donations be reduced to protect what they are entitled to. If there are no legitimate children and no other compulsory heirs whose legitimes are prejudiced, there may be no one with standing to demand reduction. Whether a reduction is warranted, and how to compute it, depends on the full picture of the estate's value, the number and category of heirs, and the total value of all donations made — facts that require careful accounting and, usually, legal guidance.