Article 35(4) of the Family Code provides that bigamous or polygamous marriages not falling under Article 41 (presumptive death) are void from the beginning.
Art. 41. A marriage contracted by any person during the subsistence of a previous marriage shall be null and void, unless before the celebration of the subsequent marriage, the prior spouse had been absent for four consecutive years and the spouse present had a well founded belief that the absent spouse was already dead. In case of disappearance where there is danger of death under the circumstances set forth in the provisions of Article 391 of the Civil Code, an absence of only two years shall be sufficient.
For the purpose of contracting the subsequent marriage under the preceding paragraph, the spouse present must institute a summary proceeding as provided in this Code for the declaration of presumptive death of the absentee, without prejudice to the effect of reappearance of the absent spouse.