There are some heirs, called legitimates, who are entitled, under the law, to a portion of the estate that cannot be freely disposed of in a will.
Legitimate heirs are the spouse (who has not renounced this quality before the marriage), sons (or grandsons) and fathers (or grandfathers), in order and according to the rules of legitimate succession.
The portion of assets that cannot be disposed of changes according to the legitimate heirs who compete for succession.
If only the spouse survives the deceased, leaving no children, grandchildren, parents or grandparents, his portion corresponds to half of the inheritance. The remainder may be left, in will, to other people.
If, however, the deceased’s children compete with the spouse, the portion of the inheritance which cannot be freely disposed of amounts to 2/3 of the inheritance. In this case, the will can only refer to the remaining third of the assets/estate.
If no spouse survives the deceased, the legitimate heirs will be his children (or grandchildren) and, in this case, the portion of the inheritance that belongs to them shall be half (one child) or two thirds (two or more children) of the assets.
If only the spouse and parents (or grandparents) survive, they are entitled to 2/3 of the inheritance.
Finally, if there is no spouse or children (or grandchildren), the parents (or grandparents) will be the only legitimate heirs. In this case, they will be entitled to half or 1/3 of the inheritance, depending on whether they are parents or grandparents/great-grandparents / etc.
The assets disposed of in the will cannot affect the portion of the inheritance that belongs to these legitimate heirs and, if this happens, the will dispositions shall be reduced accordingly.