Short answer. Against your legitime. Article 909 of the Civil Code states that donations given to children shall be charged to their legitime — not to the freely disposable portion. This means the house you received counts as an advance on your reserved share, not as a gift from outside your inheritance.
What the law says
Donations given to children shall be charged to their legitime.
Civil Code, Article 909 — Charging Donations To Shares. Read the full provision →
The rule: donations to children come from their legitimate share
Article 909 of the Civil Code draws a clear distinction between two classes of donee. For children — who are compulsory heirs — the law says: "Donations given to children shall be charged to their legitime." The house your father gave you during his lifetime is treated as an advance on the share the law already reserved for you. When the estate is settled, the house value is factored into what you have already received, and your share of the remaining estate is computed accordingly.
Why this rule exists
Charging donations to the legitime prevents a parent from favoring one child over others by giving large gifts during life and then leaving an undivided estate for all children to share equally at death. Without this rule, a parent could give most of the estate to one preferred child while that child also collected a full pro-rata share at death. By treating the lifetime gift as an advance on the legitime, the law preserves rough parity among compulsory heirs — the child who received more during the parent's life gets correspondingly less from the estate.
What happens if the donation exceeds the legitime
Article 909 adds that donations — whether to children or to strangers — "shall be reduced according to the rules established by this Code" insofar as they are inofficious or exceed the disposable portion. If the house you received was worth so much that it exceeded your entire legitime, the excess may be subject to reduction if it ate into the free portion beyond what the law allows. Whether that excess is inofficious depends on a computation of the entire estate, all compulsory heirs, and all donations subject to collation — a calculation that usually requires accounting for the full picture of the parent's assets and gifts.
Donations to strangers: a different rule
By contrast, Article 909 directs that donations to strangers — people who are not compulsory heirs — are charged to the part of the estate the testator could dispose of by will: the free portion. This means gifts to a friend, a charity, or a non-heir relative do not diminish the reserved shares of the compulsory heirs unless they exceed the free portion entirely. The distinction matters when computing how much the compulsory heirs should receive and whether any donations must be reduced to protect those reserved shares.