Family Code, Art. 170

The action to impugn the legitimacy of the child shall be brought within one year from the knowledge of the birth or its recording in the civil register, if the husband or, in a proper case, any of his heirs, should reside in the city or municipality where the birth took place or was recorded. If the husband or, in his default, all of his heirs do not reside at the place of birth as defined in the first paragraph or where it was recorded, the period shall be two years if they should reside in the Philippines; and three years if abroad. If the birth of the child has been concealed from or was unknown to the husband or his heirs, the period shall be counted from the discovery or knowledge of the birth of the child or of the fact of registration of said birth, whichever is earlier. (263a)